Periodic Dust Formation around WR 140;
Dust Properties Examined by the Multi-Epoch Mid-Infrared SED Analyses
I.Sakon,1 R.Ohsawa,1 T.Nakamura,1 T.Onaka,1 T.Nozawa,2 T.Kozasa,3 and T.Fujiyoshi4
1Department of Astronomy, Graduate School of Science, University of Tokyo, Japan
2Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo, Japan
3Department of Cosmosciences, Graduate School of Science, Hokkaido University, Japan
4Subaru Telescope , National Astronomical Observatory of Japan, USA
Massive stars are expected to play an important role in predominately supplying metal elements
and dust particles into the interstellar space in the early universe due to their short lifetime in themain sequence. The amount of newly formed dust in the ejecta of a supernova obtained from theobservational results, however, remains only in a range of 10-3-10-5Msun , which is muchsmaller than the amount of dust needed for a SN to form to account for the dust content in theearly universe. Recent observations of dust-forming type-Ib supernova 2006jc made withAKARI and Spitzer have shown that the newly-formed dust in the SN ejecta is also only in therange of 10-4-10-5Msun (Sakon et al. 2009; Mattila et al. 2008), but they recognize the presenceof pre-existing circumstellar dust possibly formed in the mass loss wind associated with theevents prior to the SN explosion. Recent studies reveal that many of the Wolf-Rayet stars formin binary system and that around 10% of WR stars may form carbon-rich dust in their windwind collision zone whenever the secondary passes by the periastron point of the primary.
Therefore, whether or not such WR binary systems should have made significant contribution
toward supplying dust particles in the early universe has to be verified from the observational
point of view. In this presentation, we present the results of the multi-epoch Mid-Infraredobservations of a long period (P=7.93years; Williams 2011) colliding-wind Wolf-Rayet binary
system WR140 with Subaru/COMICS. The observations have been carried out over 3 years
since after the last periastron event in 2009. The properties of dust in the expanding concentricarc structures (see Fig. 1) formed during the 2001 and 2009 periastron events are examinedbased on the mid-infrared SED analyses.
Subaru/COMICS N11.7 (11.7μm)

Jun. 2011

dust arc structure formed
during the 2009 periastronWC7 WR star + O4 star

dust arc structure
formed during the2001 periastron1”

Figure 1: Subaru/COMICS N11.7 band image of WR140 on June 2011 (orbital phased =0.3)

References
[1]
[2]
[3]

Mattila, S., et al.2008, MNRAS, 389, 141
I. Sakon, et al. 2009, ApJ, 692, 546
P. Williams, 2011, BSRSL, 80, 595

Growth of Dust Aggregates in Protoplanetary Disks andReexamination of Particle Interaction model
H. Tanaka1
1

Institute of Low Temperature Science, Hokkaido University, Japan

Dust growth is the first step of planet formation in protoplanetary disks. Dust growth
also influences temperature structure and chemical reactions in protoplanetary disks. However,
we still have a large uncertainty in the dust growth process. This uncertainty mainly comesfrom unknown factors in dust internal structure and collisional outcomes. The dust structure
and the collisional outcome would be closely related with each other. In recent years, many
theoretical studies on aggregate collisions and growth have been done. In the present talk, we
introduce remarkable results in these theoretical studies, mainly focusing on numericalsimulations of dust collisions done by our group. We obtained the following results from ournumerical simulations. (1) Icy dust aggregates can grow for high-speed collisions with up to
60m/sec [1]. (2) Dust aggregates compressed with collisions have a structure with the fractal
dimension of 2.5 [2,3,4] (also see Fig1). (3) Because of the low fractal dimension ofcompressed aggregates, collisional compression is not effective, which makes the bulk densityof dust aggregates extremely low (~10-5 g/cm3)[3,5]. These rather surprising results in our
numerical simulations are dependent on the interaction model between sub-micron constituent
particles of dust aggregates. We also have started the reexamination of the particle interaction
model, by performing molecular dynamics simulation of particle collisions. We report the
preliminary results of our molecular dynamics simulations, too. Our preliminary results
support the particle interaction model in the previous studies [6].

Figure 1: Structure and the bulk density of growing dust aggregates in numericalsimulations[3].
References
[1]
[2]
[3]
[4]
[5]
[6]

Wada, K., Tanaka, H., Suyama, T., Kimura, H., & Yamamoto, T. 2009, ApJ, 702, 1490
Wada, K., Tanaka, H., Suyama, T., Kimura, H., & Yamamoto, T. 2008, ApJ, 677, 1296
Suyama, T., Wada, K., & Tanaka, H. 2008, ApJ, 684, 1310
Suyama, T., Wada, K., Tanaka, H. & Okuzumi, S. 2012, ApJ, 753, 115
Okuzumi, S., Tanaka, H., Kobayashi, H., & Wada, K. 2012, ApJ, 752, 106
Tanaka, H., Wada, K., Suyama, T. & Okuzumi, S. 2012, PThPS 195, 101

Observations of Interstellar Ices
Adwin Boogert1
1Infrared Processing and Analysis Center, Caltech, USA
The icy grain mantles in dense interstellar and circumstellar environments are formed by acomplex interplay of chemical and physical processes. Key questions on the formation andevolution of the ices must be answered by the combination of observations, chemical
modeling, and laboratory experiments. Recent infrared (2-30 micron) spectroscopic surveysof large samples of Young Stellar Objects (YSOs) [1] and background stars tracing quiescentcloud material [2] have shown that the ice abundances and absorption band profiles varyconsiderably as a function of environment. Using laboratory spectra in the identification
process (Figure 1), it is clear that a rather complex mixture of simple species (CH3OH, CO2,
H2O, NH3, CO) exists even in the quiescent cloud phase. In particular, our discovery offrozen CH3OH in some isolated dense cores, and its absence in others, show that local
physical conditions (CO freeze out) and time scales (CH3OH formation) are key factors in thechemistry before star formation occurs. Sublimation and thermal processing of the ices are
dominant processes during the YSOs evolution. The identification of several ice absorption
features is still disputed. I will outline laboratory work needed to further constrain the iceband identification as well as the thermal and chemical history of the carriers. Suchexperiments will also be essential to interpret future high spectral resolution SOFIA andJWST observations.

Figure1:Mid-infrared spectra of a star tracing quiescent cloud material (top), a low mass YSO (middle) and a
massive YSO. For each source, the smooth red line is a laboratory spectrum of pure amorphous H2O ice at
10 K. The green line below that includes laboratory spectra of frozen H2O, CH3OH, CH4, CO2, NH3,HCOOH, and H2CO. Clearly, a significant fraction of the absorption remains unexplained.

References[1][2]

A. Boogert, et al., 2008, ApJ 678, 985.
A. Boogert, et al., 2011, ApJ 729, 92.

Ice chemistry in the Magellanic Clouds
T. Shimonishi,1 T. Onaka,2 Y. Aikawa1, I.Sakon2, Y. Ita3, A. Kawamura4, and H. Kaneda5
1Department of Earth and Planetary Sciences, Graduate School of Science, Kobe University
2Department of Astronomy, Graduate School of Science, The University of Tokyo
3Astronomical Institute, Graduate School of Science, Tohoku University
4National Astronomical Observatory of Japan
5Graduate School of Science, Nagoya University

Recent advances in infrared observational instruments enable us to detect spectral
information of young stellar objects (YSOs) in extragalaxies. Star-/planet-formation
activities can occur in various types of galaxies which differ in various points such as size,
shape, and environment. In order to understand the diversity of materials in the universe, it
is very important to investigate how galactic characteristics affect the properties ofmaterials around YSOs.
The Large and Small Magellanic Clouds are the nearest galaxies to our Galaxy (~50 kpc for
LMC, and ~60 kpc for SMC). Metallicities of the LMC and the SMC are known to beapproximately 1/2 and 1/5 compared to the solar neighborhood. Thus, YSOs in the
Magellanic Clouds enable us to investigate how the different metallicity environments affectthe properties of circumstellar materials. Chemical evolution of the universe is, as a first-orderapproximation, the evolution of metallicity. In this respect, it is especially important toinvestigate YSOs in low-metallicity environments.
For the last few years, it has been pioneer days for spectroscopic studies of YSOs in the
Magellanic Clouds. A number of embedded YSOs are spectroscopically identified in the
LMC and SMC, and their infrared ice features are investigated in detail (e.g., [1], [2], [3]).
In this presentation, I'm going to discuss the properties of circumstellar ices around high-mass
YSOs in the LMC and SMC based on infrared spectroscopic data obtained with the AKARI
satellite. It is shown that ices around YSOs in the Magellanic Clouds possess different
properties in terms of molecular abundances and column densities for such major species aswater, carbon dioxide, and carbon monoxide. In addition to the observational discussions, I'm
going to present the preliminary results of numerical simulations on dust surface reactions
under the unique environment of the Magellanic Clouds. The effect of galactic environmenton the ice chemistry will be discussed from the point of view of observations and chemical
calculations.
References[1][2]

T. Shimonishi, et al., 2008, ApJ, 686, L99
T. Shimonishi et al., 2010, A&A, 514, A12[3] T. Shimonishi, 2012, Ph.D thesis

Systematic study of interstellar ices in nearby galaxies
M. Yamagishi1, H. Kaneda1, S. Oyabu1, D. Ishihara1, T. Onaka2, T. Shimonishi3, T. Suzuki4
1

Graduate School of Science, Nagoya University, Japan
Graduate School of Science, The University of Tokyo, Japan
3
Graduate School of Science, Kobe University, Japan
4
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan
2

Many important spectral features are included in a near-infrared (IR) wavelength range, whichenable us to investigate the interstellar environments of galaxies. In particular, spectral
absorption features due to interstellar ices, especially H2O and CO2 ices, provide us crucial
information on the present and past interstellar environments, and thus the evolutionary
histories of galaxies. More specifically, we can derive information on temperature, chemical
condition, and radiation history of the interstellar medium from ices. Before AKARI, however,few detections of ices were reported for nearby galaxies. The AKARI's unique capability ofnear-IR spectroscopy with high sensitivity enables us to systematically study ices in nearby
galaxies.
We explored many near-IR spectra (2.5 – 5.0 microns) of the 211 pointed observations, whichwere carried out within the framework of the AKARI mission program, "ISM in our Galaxy
and Nearby galaxies (ISMGN)". As a result, out of 122 nearby galaxies, we have significantly
detected H2O ice from 36 galaxies and CO2 ice from 9 galaxies. It is notable that the ices aredetected not only in late-type galaxies but also in early-type galaxies. We have evaluated thecolumn densities of the ices, visual extinctions (Av), and spectral feature intensities ofpolycyclic aromatic hydrocarbons (PAHs) and Brα from the spectra. Then we find a global
correlation between the column densities of the H2O ice and the Brα intensities, but nocorrelation between those and Av. In this presentation, we show the results of our systematic
study on ices in nearby galaxies, and discuss their physical implications for the interstellar
environments of the galaxies.

Figure 1: Example of the AKARI near-IR spectra obtained for the central region of M 82.

The chemistry of interstellar ice: the case of purely thermal reactions.

P. Theulé, F. Duvernay, G. Danger, F. Borget, J.B. Bossa, F. Mispelaer,
V. Vinogradoff, J. Noble, and T. Chiavassa
Aix-Marseille Univ, PIIM UMR 7345, 13397, Marseille, France CNRS, PIIM UMR 7345,
Marseille, 13397, France

Complex organic molecules are widely observed in star formation regions, although theirformation mechanisms are not well understood. Although solid-state chemistry is thought toplay a dominant role in their formation, the solid-state reaction network is poorly known. We
want to emphasize the role of purely thermal reactions involving stable reactants. These
reactions lead to the formation of complex organic molecules, which are either released into
the gas phase or incorporated into an organic residue. Unlike non-thermally induced reactions,
thermal reactions are important because they are not limited by the UV or particles flux, andcan occur despite the slow diffusion of the reactants. Moreover, both surface and mantle
molecules can react. However, these reactions have large activation energies, theastrophysical relevance of which can be measured experimentally. Thermal reactions
represent an important step towards the formation of complex organic molecules and need to
be included as supplementary reactions in existing grain chemistry networks.

Interaction of Charged Particles with Kuiper Belt Ices and Astrobiological Implications
R.I. Kaiser,1,2 B. Jones1
1

Department of Chemistry, University of Hawaii at Manoa, Hawaii, USA & W.M. Keck
Laboratory in Astrochmistry, Hawaii, USA
2
NASA Astrobiology Institute, University of Hawaii at Manoa, Hawaii, USA

The Kuiper Belt consists of about 70,000 icy bodies, which extend beyond the orbit of Neptune at
30 AU. These bodies are thought to have maintained low temperatures (30-50 K) since theformation of the Solar System and therefore hold a well-preserved record of the primitive
volatiles from which the solar system formed. While the icy inventory consist of water, observations have also confirmed the presence of methane, ammonia, carbon monoxide, nitrogen,carbon dioxide, and methanol. These surfaces have been exposed to galactic comic radiation(GCR) and solar wind particles, which are thought to produce biologically important species.
Since KBOs are also considered as ‘precursor objects’ to short periodic comets, KBOs might bealso a source to bring such molecules to the primordial Earth, perhaps helping to instigate theorigin of life. Our research has been focused on trying to understand how these ices have evolved
over the age of our solar system under the chemical processing – primarily of species containing
the atoms carbon, hydrogen, oxygen and nitrogen – and to what extend the variation of composition and temperature may help explain these observations and enable us to trace backwards, todetermine the primordial composition of the solar system. Results on the formation of simple
sugars such as glycolaldehyde, amino acids like glycine, carboxylic acids, and molecules carrying
the peptide bond (form amide, dipeptides) will be presented. We also present new results fromthe newly commissioned W.M. Keck Research Laboratory in Astrochemistry at the University of
Hawai'i at Manoa. This lab comprises a next generation ultra-high vacuum experimental set-up
which allows the study of the interaction of monoenergetic photons and charged particles with icy
surfaces using a plethora of complementary analytical techniques within a single machine
including Fourier Transform Infrared, Raman, and UV-VIS spectroscopy, as well as quadrupole
and time-of-flight mass spectrometry coupled with soft vacuum ultraviolet photoionization. Here,
we present recent results regarding the formation of high molecular weight (~ C18) hydrocarbons
starting from pure, simple hydrocarbons ices upon interaction of these ices with ionizing
radiation: methane (CH4), ethane (C2H6), propane (C3H8) and n-butane (C4H10). Specifically, we
have utilized for the very first time a novel application of reflection time-of-flight mass spectrometry to observe the nature of high mass hydrocarbons as a function of their respective sublimation temperature. Coupled with soft vacuum ultraviolet photoionization of the subliming
products at 10.5 eV, generated via tripling in a pulsed xenon jet of the 355 output of a Nd:YAG
laser, our results indicate that larger, more complex hydrocarbons up to C18 are formed easily
under conditions relevant to the environment of Kuiper Belt Objects which may help elucidatepart of the puzzle regarding the ‘colors’ of these objects along with the formation of carbonaceous
material throughout the interstellar medium.

Figure 1: Time-of-Flight spectra as a function of temperature of the newly formed hydrocarbon species
from the energetic processing of a pure amorphous ethane ice taken at a photoionization energy of 10.5 eV.

Proton transfer reaction at the air-water interface
S. Enami,1,2,3 M. R. Hoffmann,4 and A. J. Colussi41

The Hakubi Center for Advanced Research, Kyoto Univ. Japan
Research Institute for Sustainable Humanosphere, Kyoto Univ., Japan
3
PRESTO, Japan Science and Technology Agency, Japan
4
Ronald and Maxine Linde Center for Global Environmental Science, California Institute ofTechnology, U.S.A
2

Proton transfer (PT) through and across aqueous interfaces is a fundamental process inchemistry and biology. Unveiling the mechanism will help to understand the ubiquitous
nature of PT at other interfaces, such as vacuum-ice
interfaces. Notwithstanding its importance, it is not
generally realized that interfacial PT is quite different fromconventional PT in bulk water. Here the mechanism of PT
across air-water boundaries is investigated in experiments
in which the protonation/deprotonation of gaseous
trimethylammine (TMA)1,2, n-hexanoic acid (PCOOH)3,
nitric acid (HNO3)4 and isoprene (ISO)5 upon collision
with liquid water microjets is monitored by online
electrospray mass spectrometry as a function of bulk pH.
We found, although PCOOH(aq) is a very weak base FIGURE 1 Hydronium becomes a(pKBH+ < -3), PCOOH(g) is converted to PC(OH)2+ on superacid once it appears at thewater’s surface.
pH < 4 water via a process that ostensibly retains someof the exoergicity of its gas-phase counterpart, PCOOH+ H3O+ = PC(OH)2+ + H2O, ΔG < -22 kcal mol-1. We
infer that H3O+ emerges at the surface of pH < 4 waterand behaves as a superacid (Fig. 1). The extremely large
kinetic isotope effects (KIE) observed on H2O/D2O
microjets and their inverse dependences on pH indicatethat protonation of PCOOH(g) on water (1) involves
tunneling, (2) is faster than H-isotope exchange, and (3)is progressively confined to the outermost layers as
water becomes more acidic (Fig. 2). PT across steep FIGURE 2 Extremely large KIE for thewater density gradients appear to be promoted by both protonation of gaseous PCOOH(g) on
H2O/D2O (5/95) microjets as functions
dynamic and thermodynamic factors.
of bulk pD.

【References】(1)
Enami, S.; Hoffmann, M. R.; Colussi, A. J. Proton Availability at the Air/Water Interface. J. Phys.
Chem. Lett. 2010, 1, 1599-1604.
(2) Enami, S.; Hoffmann, M. R.; Colussi, A. J. Molecular Control of Reactive Gas Uptake "on Water".
J. Phys. Chem. A 2010, 114, 5817-5822.
(3)
Enami, S.; Stewart, L. A.; Hoffmann, M. R.; Colussi, A. J. Superacid Chemistry on Mildly Acidic
Water. J. Phys. Chem. Lett. 2010, 1, 3488-3493.
(4)
Mishra, H.; Enami, S.; Nielsen, R. J.; Hoffmann, M. R.; Goddard, W. A.; Colussi, A. J. Anions
Dramatically Enhance Proton Transfer through Water Interfaces. Proc. Natl. Acad. Sci. U .S. A. 2012, 109,10228-10232.
(5)
Enami, S.; Mishra, H.; Hoffmann, M. R.; Colussi, A. J. Protonation and Oligomerization of
Gaseous Isoprene on Mildly Acidic Surfaces: Implications for Atmospheric Chemistry. J. Phys. Chem. A 2012,
116, 6027-6032.

COM’s and Their Formation in Assorted Sources
E. Herbst1
1

Departments of Chemistry and Astronomy, University of Virginia, Charlottesville, Virginia
USA

Complex organic molecules (COM’s) are partially saturated molecules with six or more
atoms [1] found in the gas phase of assorted interstellar sources such as hot cores and corinos,
cold dense cores, and infra-red dark clouds. Perhaps the best-known molecule of this classis methyl formate (HCOOCH3).
Although these species are detected in the gas, theirformation involves both grain surface and gas-phase chemistry. In hot cores and corinos,
COM’s are most likely formed during the warm-up phase of protostellar sources as gas anddust collapse towards the central protostar or towards a growing protoplanetary disk [2].
Here the rising temperature is necessary to allow fragment radicals, formed by photolysis, todiffuse on grain surfaces and recombine with each other rather than with hydrogen atoms, andto allow the newly formed COM’s to desorb into the gas phase.
In cold cores, theformation of COM’s likely depends upon transitory heating of grains allowing both reactions
and desorption of the products before cooling. In protoplanetary disks, COM’s can beformed even on cold icy grains because of the high densities compared with interstellar
clouds, which result in a reduction of the normally significant amount of atomic hydrogen on
cold surfaces [3]. In these sources, however, most of the COM’s remain in the ice because
the temperature never rises to their sublimation points and photodesorption is generally
inefficient. In infrared dark clouds, the mechanism for formation of these species, whichhave been newly detected, is unclear although one possibility is shock desorption from grainsurfaces, as has also been posited for the galactic center.
In the talk, I will discuss how COM’s are formed and how abundant they can become in both
the gas and in granular ices for assorted sources. New work on their possibly highabundance in protoplanetary disks will be emphasized with the goal of understanding theoriginal organic inventory of planets and other objects such as comets.

References
[1]
[2]
[3]

E. Herbst & E. F. van Dishoeck, 2009, ARAA 47, 427.
R. T. Garrod, S. L. Widicus Weaver, & E. Herbst, 2008, ApJ 682, 283
C. T. Walsh, T. J. Millar, H. Nomura, E. Herbst, S. L. Widicus Weaver, & Y. Aikawa, A&A, in
preparation

Water and organic molecules in protoplanetary disks
H. Nomura,1 C. Walsh,2 D. Heinzeller3 and T.J. Millar2
1

Department of Astronomy, Graduate School of Science, Kyoto University, Japan
2
ARC, School of Maths and Physics, Queen’s University Belfast, UK
3
Meteological Service of New Zealand Limited, New ZealandProtoplanetary disks surrounding young stars provide peculiar environment for astrochemistry.
The disk surface is exposed to strong UV and X-ray irradiation from the central star, while theouter region of the disks is cold and molecules are frozen onto dust grains to form more
complex species via surface reactions. The gas density is much higher than molecular clouds,
and dust grains are thought to stick together as well as settle towards the disk midplane to leadto planet formation, which also makes specific environment.
We have studied the chemical structure of protoplanetary disks using a comprehensive
astrochemical reaction network, based on a detailed model for the gas and dust temperatureand density profiles, which takes into account UV and X-ray irradiation from the central star.
Here we especially focus on abundance profiles and line emission of water and organic
molecules in the disks with considering effects of some physical processes, such as dust
evolution and turbulent mixing. Water and some organic molecules are basically formed via
endothermic reactions in the hot gas in the inner disk surface, while they are photodesorbed
from dust grains in the cold outer disk. Our results show that turbulent mixing enhances waterat the hot surface layer of the inner disks, while it doesn't affect very much in the cold outerdisk. On the other hand, the dust evolution changes the gas temperature and amount ofradiation field so that it makes water-abundant-region shrunk in the hot surface layer of theinner disks, while it enhances water near the midplane in the cold outer disk. Grain surface
reaction has a significant effect on formation of complex organic molecules, and somephotodesorbed organic molecules could be detectable with ALMA. We compare the results ofour model calculations of water line fluxes with the Spitzer and Herschel observations, whichsuggests that observed water line fluxes can be reproduced only when molecular hydrogenformation rate on warm grains is small or dust grains are significantly less abundant.

References
[1]
[2]
[3]

C. Walsh, H. Nomura, T.J. Millar, & Y. Aikawa, 2012, ApJ 747, 114
D. Heinzeller, H. Nomura, C. Walsh, & T.J. Millar, 2011, ApJ 731, 115.
C. Walsh, T.J. Millar, & H. Nomura, 2010, ApJ 722, 1607

Finding of large-sized, nitrogen-rich organic materials in ultracarbonaceous Antarctic
micrometeorite
H. Yabuta,1 S. Itoh,2 T. Noguchi,3 N. Sakamoto,2 M. Hashiguchi,2 K. Abe,2 S. Tsujimoto,3 A. L.
D. Kilcoyne,4 A. Okubo,5 R. Okazaki,6 S. Tachibana,2 K. Terada,1 T. Nakamura7 and H.
Nagahara5
1

Department of Earth and Space Science, Osaka University, Japan
2
Natural History Sciences, Hokkaido University, Japan
3
College of Science, Ibaraki University, Japan
4
Advanced Light Source, Lawrence Berkeley National Laboratory, Japan
5
Department of Earth and Planetary Science, Tokyo University, Japan
6
Department of Earth and Planetary Sciences , Kyusyu University, Japan
7
Department of Earth Science, Tohoku University, Japan
Ultracarbonaceous Antarctic micrometeorites (UCMMs), first discovered by [1], represent
large sizes of high carbon contents. It has been reported extreme D-rich organic matter withboth crystalline and amorphous silicates from a UCMM, which appears to be compatible tocometary origin [2]. However, little has been known about the nature of UCMMs. In thisstudy, for an UCMM collected in 250 kg of the surface snow at the Dome Fuji Station,
Antarctica, we have carried out the systematic studies applying isotope microscopy, focusedion beam (FIB) extraction, scanning transmission x-ray microscope (STXM) and transmission
electron microscopy (TEM) observation to study the origin and formation of UCMMs.
Isotope imaging has detected a large-sized, nitrogen-rich organic material of ~10 x 20 μm2.
The distribution of sulfur is associated with with the organic material. There is no significant
difference in carbon, hydrogen, and nitrogen isotopic compositions of the UCMM from thoseof epoxy resin. A STXM C- and N- maps of the FIB section show that organic N-rich andpoor regions coexist in the object with a sharp boundary. N-XANES spectra of the N- richregions exhibit intense peaks of imine (C=N), nitrile (C≡N), and amide (NHx(C=O)C), whilethat of N-poor region shows a less characteristic spectrum that is similar to those of typicalchondritic and IDP organics [3]. It is noted that the N-XANES spectral patterns of the N-richregions are very similar to those observed from the three samples of Comet 81P/Wild 2 dust
particles [4]. Furthermore, the organic features of the UCMM in its size and N- functional
chemistry are very similar to those of CR3 chondritic organic material [5]. Thus, the organic
chemistry of the UCMM implies the very early stage of parent body aqueous alteration or
before.
References
[1]
[2]
[3]
[4]
[5]

T. Nakamura et al., 2005, Meteor. Planet. Sci. 40, A110.
J. Duprat et al., 2010, Science 328, 742.
G. D. Cody et al., 2011, PNAS 108, 19171.
B. De Gregorio et al., 2010, Geochim. Cosmochim. Act. 74, 4454.
Z. Peeters et al., 2012. 43rd LPS, Abstract #2612.

Recent Results from the HEXOS GT Key Program
N. Crockett,1 E. Bergin,1 J. Neill,1 and the HEXOS collaboration
1

Department of Astronomy, University of Michigan, USAI will present recent results from the Herschel GT key program entitled HerschelObservations of EXtra Ordinary Sources (HEXOS). In particular, I will focus on results
stemming from a "full band analysis" of a complete 1.2 THz wide spectral survey toward theOrion Kleinmann-Low nebula (Orion KL). This massive dataset, obtained using the HIFI
instrument, spans a frequency range of 490-1900 GHz and contains approximately 20,000
spectral lines from over 30 molecules. Consequently, we have modeled the molecularemission over an unprecedented range in excitation energy and, in some cases, usedthousands of lines to constrain our models. Our collection of molecular fits have: (1) yielded achemical inventory for different spatial/velocity components toward Orion KL, (2) produced
robust abundances for each molecule, (3) provided D/H ratios for some species (e.g. H2O,
H2CO, and CH3OH), and (4) allowed us to determine which molecules are emitting in thehottest gas possibly in close proximity to an embedded massive protostar. In addition, detailed
modeling of the light hydride H2S points to the presence of a hidden source of luminosity
toward the Orion hot core. If time allows, I will also present preliminary results from a similar
analysis of the HIFI spectral scan toward Sgr B2 (N), an equally rich spectrum which presents
its own unique challenges. This work was undertaken with the aid of the HEXOS Orion KL
and Sgr B2 (N) full band analysis teams.

Spectral Line Survey toward Spiral Arm in Nearby Galaxy M51
Y. Watanabe,1 K. Sorai,2 N. Sakai,1 and S. Yamamoto1
1
2

Department of Physics, The University of Tokyo, Japan
Department of Physics, Hokkaido University, JapanFor a thorough understanding of the galactic star formation history, one of the key issues isformation and evolution of giant molecular clouds (GMCs) and giant molecular associations(GMAs), because they are intermediate structure connecting the galactic structure andindividual star formation. We are going to investigate the evolutionary history and thephysical states of GMCs on the basis of their chemical compositions. As the first step, we
have conducted an unbiased spectral line survey toward a spiral arm in M51 to grasp the
averaged chemical composition of GMCs.
M51 (d = 8.4 Mpc) is a well-studied nearby galaxies for star formation and gas dynamics(e.g. Koda et al. 2009), because it has a prominent spiral arm and a plenty of molecular gas ina disk. The observed frequency ranges are 83-116 GHz and 130-146 GHz (Figure 1). We
detected 17 molecular species (c-C3H2, CCH, HNCO, HCN, H13CN, HCO+, HNC, N2H+,
CH3OH, CS, C34S, SO, C18O, 13CO, CN, C17O and 12CO) in the 3 mm band, and 4 molecularspecies (HNCO, H2CO, CH3OH and CS) in the 2 mm band. It is remarkable that CCH,
HNCO, CH3OH, N2H+, CN, and H2CO, which are unfamiliar in observations of extra-galaxies
except for those toward the nuclear region of the starburst galaxies and AGNs, are detected in
the spiral arm region. The spectrum pattern is much different from that found in massive star
forming regions like Orion KL (e.g. Tercero et al. 2011), indicating that the observed chemicalcomposition cannot simply be interpreted in terms of the sum of contributions from embedded
star forming cores. We will present the chemical compositions of M51 and comparisons themwith other galactic and extra-galactic sources.

Figure 1: Spectrum of a spiral arm in M51 (upper: 3 mm band, lower: 2 mm band).

References[1][2]

Koda et al. 2009, ApJL, 700, 132
Tercero et al. 2011, A&A, 528, 26 .

Ice deuteration: models and observations to interpret the
protostar history
V. Taquet1, C. Ceccarelli1, C. Kahane1, P. Peters2, D. Duflot2, A. Lòpez-Sepulcre1, C. Toubin2,
L. Wiesenfeld1
12Institut de Planétologie et d’Astrophysique de Grenoble, Grenoble, France
Laboratoire de Physique des Lasers, Atomes et Molecules, Villeneuve d'Ascq, France

Extremely large deuteration of several molecules has been observed around low-mass
protostars for a decade. Among them, formaldehyde and methanol present particularly highdeuteration, with observations of abundant doubly and triply deuterated isotopologues seen
with ground-based millimetric telescopes [1]. The Herschel Space Telescope, launched in
2009, is now providing measures of the deuterium fractionation of water. First results towards
the protostellar prototype, IRAS 16293, revealed that water shows HDO/H2O and D2O/H2O
ratios of ~3 and ~0.1 \% respectively [2]. Athough water shows a higher deuteration than thecosmic deuterium reservoir (10-5 relative to H nuclei), these values remain lower than the
deuteration seen in formaldehyde and methanol. Water, formaldehyde, and methanol are
believed to be mainly produced on interstellar ices in cold dark clouds. In this presentation, I
will discuss 1) a theoretical model and 2) new interferometric observations of the water
deuteration.
1) We have developed a macroscopic time-dependent gas-grain model, called GRAINOBLE[3], to study the formation and the deuteration of interstellar ices. The model follows themultilayer formation of ices distinguishing the chemical processes that occur in the mantle
inert bulk and on the reactive surface. For this purpose, a comprehensive chemical network
producing deuterated water, formaldehyde, and methanol has been considered following
recent experiments and theoretical calculations [4] [5]. A grid of several thousands of models
has been run and compared to observations toward low-mass protostars. The low deuterationof water compared to formaldehyde and methanol, can be explained by their different
chemical history. Water is mainly formed during a translucent phase at low density while
formaldehyde and methanol are rather formed in denser and colder prestellar cores, where the
CO depletion is high [4] [5].
2) Interferometric mapping of HDO has been carried out with the PdB interferometer toward
two low-mass protostars, IRAS2A and IRAS4A [6]. In both sources, the HDO emission iscompact and unresolved in the PdB 2 arcsec synthesized beam. LVG analysis of the integrated
line emission as well as other HDO lines from single dish observations [7] and H218O linefrom PdB observations [8] allows us to estimate the most reliable HDO/H2O ratio in lowmass protostars. We found a deuterium fractionation of water in IRAS2A and IRAS4A higher
to that found in IRAS 16293 [2], suggesting a water formation at high densities.
References[1] Parise, B., Ceccarelli et al. 2006, A&A, 453, 949[2] Coutens, A., Vastel, C. et al. 2012, A&A, 539, A132
[3] Taquet, V., Ceccarelli, C., & Kahane, C. 2012, A&A, 538, A42[4] Taquet, V., Ceccarelli, C., & Kahane, C. 2012, ApJL, 748, L3[5] Taquet, V., Peters, P. al. 2012, A&A, submitted[6] Taquet, V., Lòpez-Sepulcre, A. al. 2012, ApJL, submitted[7] Liu, F. C., Parise, B. et al. 2011, A&A, 527, A19[8] Persson, M. V., Jorgensen, J. K. & van Dishoeck, E. 2012, A&A, 541, A39

HNCO 2(0,2)-1(0,1) line emission from methanol maser clouds
S. Deguchi,1, 2, 3 and N. Shino,2,41Nobeyama Radio Observatory, NAOJ, Japan
Astronomical Sciences, Graduate Universities for Advanced Study, Japan
37317-4 Nishiide, Oizumi, Hokuto, Yamanashi 409-1501, Japan
4
Graduate School of Science and Engineering, Yamaguchi University, Japan2

We completed a large survey of class II methanol maser sources in the Galactic plane using
the class I methanol line at 44.069 GHz with the Nobeyama 45m telescope. In this course of
survey, we accidentally detected the 2(0,2)-1(0,1) line of isocyanic acid, HNCO, at 43.963
GHz in the same spectrometer with a band width of 250 MHz for 7 sources, most of which
exhibit strong 44 GHz methanol maser emission. Though the 5(0,5)-4(0,4) and 4(0,4)-3(0,3)
transitions of HNCO at higher frequencies have been observed in a number of molecular
clouds [1] and are known to be associated with molecular outflows, detection of the2(0,2)-1(0,1) line at 43.963 GHz was reported only as a private communication [2], or its
spectrum was shown only for TMC1 [3]. Here we report on the observations of thistransition of HNCO in a part of the methanol maser survey.
A dichotomy of methanol maser sources into class I and class II [4] has often been used forstar forming regions; the former emits 36, 44, and 96 GHz methanol masers, and the latter
6.7 and 12 GHz methanol masers. However, some maser sources exhibits both characteristics.
To investigate this phenomenon, we surveyed 214 IRAS sources with the 6.7 GHz methanol
emission (Class II) using the 44 GHz methanol line (Class I) at Nobeyama, and detected 89
sources in the 44 GHz line. In addition, we detected very strong 44 GHz methanol maser inthe dark cloud G359.94+0.17 toward the Galactic center [5].
Emission from the HNCO 2(0,2)-1(0,1) line was found in 7 sources, 6 of which exhibits
relatively strong 44 GHz methanol maser line. Among them, IRAS 18321-0843 shows avery broad line width of about 30 km/s, which indicates an association with the rapid
outflow. This cloud also exhibits SiO thermal emission at 43.4 GHz, and very broad ammonia
emission at 23.7 GHz. These facts show strong evidence that isocyanic acid and methanol
molecules are both evaporated from ice grains which were hit by shock in outflow.
References
[1]
[2]
[3]
[4]
[5]

J. M. Jackson, J. T. Armstrong, & A. H. Barrett, 1984, Apj, 280, 608
F. Lovas, 2004, J. Phys. Chem. Ref. Data 33, 177
N. Kaifu, M. Ohishi, K. Kawaguchi, S. Saito, & S. Yamamoto, et al. 2004, PASJ, 56, 69
K. M. Menten, 1991, in ASPS Conf. Ser. 16, 119
S. Deguchi, D. Tafoya, & N. Shino, 2012, PASJ, 64, 5.

First light observation of GIGMICS (germanium immersion grating mid-infraredcryogenic spectrograph) by Kanata 1.5-m Telescope at Higashi-Hiroshima Observatory
Y. Hirahara,1 K. Aoki1, K. Ohta1, S. Shibata1, T. Hirao1, Y. Tatamitani1, N. Ebizuka2,
K. Kawabata3, M. Yoshida3, M. Uemura3, T. Oosugi3,
K. Kawaguchid, R. Fujimorid, H. Ohiwad and H. Nagahirod
1

Graduate School of Environmental Studies, Nagoya University, Japan
2
Plasma Nano-Technology Center, Nagoya University, Japanc
Hiroshima Astrophysical Center, Hiroshima University, Hiroshima, Japan
4
Department of Chemistry, Okayama University, Japan
We have developed a germanium immersion grating mid-infrared cryogenic spectrograph(GIGMICS) designed for the Nasmyth focus stage of NAOJ Subaru 8.2-m telescope, which
operates at N-band (8-13μm) in wavelength with maximum resolving power R（≡λ/Δλ） ~40,000. A single crystal germanium echelle immersion grating (30×30×72 mm) for collimatedbeam size of 28 mmφ was fabricated by utilizing ultra-precision micro-grinding method
coupled with the ELID (Electrolytic In-process Dressing) technique (Ohmori, H. 1992[1],Ebizuka et al. 2003[2], Tokoro et al. 2003[3]).
After the critical test for the application to the laboratory gas-phase IR high-resolution
spectroscopy(Hirahara et al. 2010[4]), we have conducted the “first light” astronomical
observation of GIGMICS by the Kanata 1.5-m telescope at Higashi-Hiroshima Observatoryfrom January to April, 2011. Toward many astronomical objects such as the Moon, Venus,
Jupiter, circumstellar envelopes of late-type stars, proto-planetary nebulae in the vicinity ofstar-forming regions, we conducted spectroscopic observations in the N-band region.
As a result, we detected 24 lines of 12CO2 (v1, v 2l, v3)=(0, 11, 1) ← (1, 11, 0) and 11 lines of13
CO2 (0, 00, 1) ← (1, 00, 0) transitions in Venus (Fig. 1). Among these two transitions, 13
lines were detected for the first time(Hirahara et al. 2012[5]). Toward the planetary nebula
NGC7027, We detected [S IV] forbidden emission line (2P3/2→2P1/2) at 10.510μm, andinvestigated the spatial distribution for the first time in the ground based observation.

Figure 1. Spectrum of the Venusian 13CO2 (0, 00, 1) ← (1, 00, 0) (●) and 12CO2 (0, 11, 1) ← (1, 11, 0) (○)
rotational and vibrational transitions. The strong absorption marked with ＊show the telluric CO2 lines.

References[1] H. Ohmori 1992, Int. J. Jpn. Soc. Prec. Eng. 26, 273. [2] H. Ebizuka et al. 2003, Proc. SPIE 4837, 293.
[3] H. Tokoro et al. 2003, Proc. SPIE, 4841, 1016.
[4] Y. Hirahara et al. 2010, Proc. SPIE 7735, 77351B.
[5] Y. Hirahara et al. 2012, Proc. SPIE, in press.

Cold ion chemistry using the ion trap technique
K. Okada,1 T. Furukawa,1 M. Ichikawa,1 K. Yasuda1, M. Wada2 and H. A. Schuessler3
1

Department of Materials and Life Sciences, Sophia University, Japan
2
Nishina Center for Accelerator-Based Science, RIKEN, Japan3
Department of Physics,Texas A & M University USA

The cold ion-molecule reactions play important roles in synthesis of interstellar molecules,
and their reaction-rate constants are important information for studying the chemical
evolution of interstellar clouds [1]. Therefore, the databases of the rate constants weredeveloped for astrochemistry and some reaction network models were proposed to understandthe synthetic mechanisms of interstellar molecules [2, 3]. Recently, the present state ofknowledge concerning the reaction-rate constants and their uncertainties for the major gasphase chemical processes was reviewed [4]. It was pointed out that most of the measurementsof ion-neutral reactions were only at room temperature or at a restricted range of temperaturesnear room temperature, even though the reactions occur actually at very low temperatures ininterstellar clouds. Especially, the cold ion-polar molecule reactions have not been studied
extensively in the laboratory, owing to some experimental difficulties, such as condensationof polar gases at relatively high temperatures. For that reason, we planned to measure thereaction rates of cold ion- molecule reactions using the ion trap technique. The main purposeof the present study is the contribution to the astronomical databases.
-11

10

-12

k (cm3/s)

10

-13

10

Theory [9]PIT [10-12]
SIFT [13]SIFT [14]Present work

-14

10

-15

10

0

10

10

1

2

10

3

10

T (K)
Figure 1: A summary of the temperature dependence of the reaction-rate constant in the NH3+ + H2 → NH4+
+ H reaction. PIT: Penning ion trap, SIFT: Selected Ion Flow Tube.

We report two experimental approaches by the ion trap technique: one is a conventional
method to measure the ion-molecule reactions by combining a cryogenic linear multipole rf
ion trap with the cold buffer-gas cooling method [5], and the other is a new method tomeasure cold ion-polar molecule reactions using a Stark velocity filter and the laser coolingtechnique [6]. The latter method can be extended to the reaction-rate measurements between
sympathetically cooled molecular ions and slow polar molecules.
In the experiment using the cryogenic linear octupole rf ion trap, we have measured thetemperature dependence in the reaction-rate constant of NH3+ + H2 → NH4+ + H [7], which is
known as a bottleneck of the gas-phase ammonia synthesis in interstellar clouds [8]. The
summary of the present measurement is shown in Fig.1. We also plot the data taken from Refs.
[9-14]. The present result well agree with the theoretical values [9]. The experimental method
and the measurement procedure will be described. We will also report recent experimental
development for studying cold ion-polar molecule reactions [15-17]. We actually performed
the reaction-rate measurement between sympathetically cooled molecular ions ( N2+, N2H+ )and slow CH3CN molecules, which were produced by a Stark velocity filter [18]. The
sequential fluorescence images of the Ca+ Coulomb crystal including N2+ ions during the cold
CH3CN + N2+ → products reaction are shown in Fig.2. The shadowed area progressively
decreases with increasing the reaction time. Since the number of N2+ ions in each image canbe determined from the structure of the images, the reaction rate can also be determined.
Preliminary results and the discussions will be presented.

Figure 2: Sequential fluorescence images of the Ca+ Coulomb crystal (bright) including N2+ ions(shadowed) during the cold CH3CN + N2+ → products reaction. The number of Ca+ was roughly estimatedto be 1.8 × 103.

References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]

E. Herbst and T. J. Millar, Low temperature and cold molecules, Chap. 1, 2008, Imperial College Press
J. Woodall et al., A & A 466, 1197 (2007).
D. Quan and E. Herbst, A & A 474, 521 (2007)
V. Wakelam et al., Space Sci. Rev. 156, 13 (2010).
D. Gerlich and S. Horning, Chem. Rev. 92, 1509 (1992).
S. Willitsch et al., Phys. Rev. Lett. 100, 043203 (2008).
K. Okada, K. Yasuda, T. Takayanagi, Low Temperature Science 66, 1 (2007) (in Japanese).
E. Herbst and W. Klemperer, ApJ 185, 505 (1973).
E. Herbst, D. J. DeFrees, D. Talbi, F. Pauzat, W.Koch, A. D. McLean, J. Chem. Phys. 94, 7842 (1991).
S. E. Barlow, G. H. Dunn, M. Schauer, Phys. Rev. Lett. 52, 902 (1984).
J. A. Luine, G. H. Dunn, ApJ. 299, L67 (1985).
S. E. Barlow, J. H. Luine, G. H. Dunn, Int. J. Mass Spectrom. Ion Proc. 74, 97 (1986).
N. G. Adams and D. Smith, ApJ. 317, L 25 (1987).
H. Böhringer, Chem. Phys. Lett. 122, 185 (1985).
K. Okada et al., Phys. Rev. A 81, 013420 (2010).
N. Kimura et al., Phys. Rev. A 83, 033422 (2011).
K. Okada et al., to be published in the Journal of Physics: Conference Series 2012.
S. A. Rangwala et al., Phys. Rev. A 67, 043406 (2003).

The Cologne Database for Molecular Spectroscopy:
Recent Developments and Outlook for ALMA
Holger S. P.Müller, C. P. Endres, J. Stutzki, S. Schlemmer
I. Physikalisches Institut, Universität zu Köln, Germany

More than 10 years ago, the Cologne Database for Molecular Spectroscopy, CDMS, wasfounded to provide in its catalog section rest frequencies with sufficient accuracy on mostly
molecular species which have been or may be observed in space by largely radio astronomicalmeans. Entries are usually generated from critically evaluated laboratory data employing
established Hamiltonian models. Each molecule has a separate entry, minor isotopic species
are always, excited vibrationally states are usually presented separately. The CDMS isavailable on the internet free of charge [1], and a very early [2] as well as a more recent
account have been published.
As of September 2012, the CDMS has more than 650 entries, of which at least 280 have been
detected in space. Moreover, they make up a large fraction of the more than 170 different
molecules which have been detected in the interstellar medium or in circumstellar envelopesof late-type stars. Access to the CDMS has increased steadily, and it is at present at a level ofaround 2000 accesses each month.
Future entries will be generated in particular to support observations with ALMA. Hence, thefocus will shift to complex molecules as well as vibrational or isotopic satellites of known
interstellar molecules, which will be important in observations of star-forming regions, and tometal containing or other refractory molecules which may be observed increasingly incircumstellar envelopes of late-type stars.
Initially, entries were created as ascii tables. About 3 years ago, a process has been initiated to
put the CDMS into a database environment in the framework of the Virtual Atomic andMolecular Data Centre (VAMDC) [4,5]. The release of a test version is intended for
September 2012. The advantages of this transition as well as various aspects of the CDMS
will be presented.

References
[1]
[2]
[3]
[4]
[5]

http://www.astro.uni-koeln.de/cdms/
H. S. P. Müller, S. Thorwirth, D. A. Roth, and G. Winnewisser, 2001, A&A 370, L49.
H. S. P. Müller, F. Schlöder, J. Stutzki, and G. Winnewisser, 2005, J. Mol. Struct. 742, 215.
M. L. Dubernet et al., 2010, JQSRT 111, 2151.
http://www.vamdc.org/

Radio Searches for Interstellar Carbon Chains HC4OH and H2CCC
M. Araki,1 S. Takano,2 H. Yamabe,1 N. Koshikawa,1 K. Tsukiyama,1 A. Nakane,3T. Okabayashi,3 A. Kunimatsu4 and N. Kuze4
1

2

Faculty of Science Division I, Tokyo University of Science, Japan
Nobeyama Radio Observatory and the Graduate University for Advanced Studies(Sokendai), Japan
3
Faculty of Science, Shizuoka University, Japan
4
Faculty of Science and Technology, Sophia University, Japan

We have made a sensitive search for the rotational transitions of the interstellar carbon
chains HC4OH and H2CCC.
The carbon-chain alcohol HC4OH have searched in the frequency range from 21.2 to46.7 GHz in the star forming region L1527 in Taurus with rich carbon-chain chemistry[1]. The incentive of this observation was a laboratory detection of HC4OH by the
microwave spectroscopy [2]. Despite achieving an rms of several mK in antenna
temperature by the 45m telescope at Nobeyama Radio Observatory, the search for
HC4OH was negative, leading to a 5 sigma upper limit corresponding to the column
density of 4 × 1012 cm-2 based on the excitation temperature of 12.3 K. The upper limit
indicates that the [HC4-OH]/[HC4-CN] ratio is less than 1.0. The ratio suggests that thecyanide species with carbon-chain structure is dominant in comparison with thehydroxyl one in L1527, which can be the opposite case of saturated compounds, e.g.
CH3OH and CH3CN, in hot cores and dark clouds.
In order to clarify the authenticity of a recently proposed identification of H2CCC(linear-C3H2) as a diffuse interstellar band carrier [3], we searched for the rotationaltransition of H2CCC at a frequency of 103 GHz toward HD 183143 using the 45m
telescope at Nobeyama Radio Observatory [4]. Although an rms noise level of 32 mK in
the antenna temperature, TA*, was achieved, detection of H2CCC was unsuccessful,producing a 3 σ upper limit corresponding to a column density of 2.0 × 1013 cm−2. The
upper limit indicates that the contribution of
H2CCC to the diffuse interstellar band at 5450 Å
toward the star HD 183143 is less than 1/25; thus,
it is unlikely that the laboratory bands of theB1B1–X1A1 transition of H2CCC and the diffuse
interstellar bands at 5450 Å (and also 4881 Å)
toward HD 183143 are related.
Figure 1: Spectrum at the line position of H2CCC
searched toward HD 183143. Solid vertical lines
indicate positions of the two velocity components of CH.
Solid curve shows a line profile of H2CCC simulated inarbitrary intensity.

References[1] M. Araki, S. Takano, H. Yamabe, N. Koshikawa, K. Tsukiyama, A. Nakane, T. Okabayashi, A.
Kunimatsu and N. Kuze, 2012, ApJ, 744, 163[2] M. Araki and N. Kuze, 2008, ApJ, 680, L93[3] J. P. Maier, G. A. H. Walker, D. A. Bohlender, F. J. Mazzotti, R. Raghunandan, J. Fulara, I. Garkusha,
A. Nagy, 2011, ApJ, 726, 41[4] M. Araki, S. Takano, H. Yamabe, K. Tsukiyama and N. Kuze, 2012, ApJ, 753, L11

High Resolution Infrared Spectra of Protonated Polycyclic Aromatic Hydrocarbons andtheir Neutral Counterparts in Solid Para-hydrogen
Yu-Jong Wu,1 M. Bahou,2 and Yuan-Pern Lee2
1

Molecular Science Group, National Synchrotron Radiation Research Center, Taiwan
2
Department of Applied Chemistry, National Chiao Tung University, Taiwan

Identification of infrared (IR) spectra of protonated polycyclic aromatic hydrocarbons(H+PAH) is important in understanding the unidentified IR emission bands (UIR) ofinterstellar media. We use protonated benzene (C6H7+) and protonated naphthalene (C10H9+)[1,2] to demonstrate a new method that has advantages over the Ar-tagging IR
photodissociation or the IR-multiphoton-dissociation methods currently used. H+PAH wasproduced on electron bombardment of a mixture of PAH and para-hydrogen during
deposition onto a target at 3.2 K. IR absorption of the matrix sample shows lines mainly due
to H+PAH and its neutral form, HPAH. Lines of H+PAH decreased in intensity when thematrix was irradiated at 365 nm or maintained in darkness, whereas those of HPAH increased
in intensity. Observed wavenumbers, relative IR intensities and deuterium isotopic shifts
agree with those predicted theoretically. This method, providing a wider spectral coveragewith narrower lines and accurate relative IR intensities, can be applied to larger PAH which
are difficult to study with other methods.

Figure 1: (A) UIR spectrum toward VV 114 [3] and IR spectra of (B) protonated benzene, (C) a-protonatednaphthalene, (D) b-protonated naphthalene, (E) protonated pyrene, and (F) protonated coronene isolated insolid parahydrogen.

References
[1]
[2]
[3]

M. Bahou, Y.-J. Wu, & Y.-P. Lee, 2012, J. Chem. Phys. 136, 154304.
M. Bahou, Y.-J. Wu, & Y.-P. Lee, 2012, submitted
E. Le Floc'h et al., 2002, A&A 391, 417

Terahertz spectroscopy of H2F+
F. Matsushima,1 T. Shiraishi, 1 C. Shinozuka,1
T. Amano, 2
R. Fujimori, 3 and K.Kawaguchi3
1

2

Department of Physics, University of Toyama, Japan
Department of Chemistry and Department of Physics and Astronomy,
The University of Waterloo, Canada
3
Department of Chemistry, Okayama University, Japan

Rotational transitions of H2F+ were observed in the THz region by using an Evenson-type
tunable far-infrared (TuFIR) spectrometer [1] which is based on the difference frequency
generation of two CO2 laser lines. H2F+ ion was generated in an extended negative glow
discharge cell [2] by a proton transfer reaction from H3+ to HF. HF was produced from HKF2
powder in a heating tube [3]. A trace of the spectral line from the lowest rotational level (111←000) is shown in Fig.1. A fitted line profile with a base line correction is also shown in the
figure. Frequencies of 7 rotational lines below 1.9 THz were measured with the present
spectrometer as shown in Table 1.
Present frequency data were analyzed together with 5 lines from submillimeter-wave
measurement [3] and 122 combination differences for the ground stete derived from theinfrared data [4,5]. Sixteen adjustable parameters of the Watson’s A-reduced Hamiltonian
were determined.

PSD output (arb. units)

Based on the TuFIR and submillimeter measurements, H2F+ lines are to be searched for with
Herschel Space Observatory.

130532013053101305300

Frequency (MHz)+Figure 1: The 111 ←000 line of H2F .

Table 1. Rotational lines of H2F+ measured
with TuFIR spectrometer.
_______________________________
transition
frequency (MHz)_______________________________
111 ← 000
1305306.503(73)1370911.418(48)303 ← 212413 ← 404
1425857.036(59)523 ← 514
1737165.499(66)422 ← 413
1748027.582(85)321 ← 312
1823629.057(70)212 ← 101
1850081.989(50)_______________________________

References
[1]
[2]
[3]
[4]
[5]

K.M. Evenson, D.A. Jennings, and F.R. Petersen, Appl. Phys. Lett., 44, 576 (1984).
T. Amano and A. Maeda, J. Mol. Spectrosc., 203, 140 (2000).
R. Fujimori, K. Kawaguchi, and T. Amano, Astrophys. J., 729, L2 (2011).
E.Schafer and R.J. Saykally, J. Chem. Phys., 81, 4189 (1984).
R. Fujimori, Y. Hirata, K. Kawaguchi, and I. Morino, In International Symposium on Molecular
Spectroscopy, volume RE02, ohio State university, Columbus, OH, USA, 2010.

Distribution of CCS and HC3N in L1147, A Less Evolved Molecular Cloud
T. Suzuki,1 T. Hirota,2 and M. Ohishi1
12

Astronomy Data Center, NAOJ, Japan
Mizusawa VLBI Observatory, NAOJ, JapanThe ratio “CCS/NH3” is a good indicator of molecular cloud age. A CCS-rich cloud isrelatively young, while a NH3-rich cloud is old[1~3]. Suzuki et al. (1992) found Carbon-chain
producing regions (CCPRs), where carbon-chain molecules are abundant but NH3 is poor [4].
These regions are considered to be in younger phase of cloud evolution.
In 2009, Hirota et al. observed 40 molecular clouds and found five CCPR candidates.
These candidates showed high “CCS/NH3” ratios, but their CCS abundances were lower thanthose of known CCPRs[5]. Molecular distributions in these clouds, which were not obtained sofar, would provide us with key information regarding their evolution. Thus we made mapping
observations in HC3N and CCS towards one of these CCPR candidates, L1147, to reveal
molecular distributions and relation with associated star formation activity.
We observed a CCS line ( (J,N) =(4,3)→(3,2)) and a HC3N line (J=5→4 ) by the
Nobeyama 45m radio telescope. We found the followings: (1) CCS and HC3N are elongatedin the NE-SW direction, (2) HC3N peak is located between two CCS peaks, and (3) the CCS
and HC3N peaks are away from Spitzer 2040567+6723050. We also made column density
maps by assuming that the lines are optically thin and the excitation temperatures are 5 K[4](Figure 1). The column densities range in 1012~1013 cm-2 which agrees well with Hirota et al.
(2009). It is noted that the “anti-correlation” between HC3N and CCS has been known toward
only one source Hirota et al. (2009).
In the poster we will discuss evolution of molecular clouds in their very young phase.

Figure 1: Column density distributions of HC3N (left) and CCS (right). The star mark corresponds toSpitzer 2040567+6723050. The reference position (0,0) corresponds to (RA(2000), Dec(2000))=(20h 40m
32 s, 67d 21 m 45 s).

References[1] Hirota, T., Maezawa, H., & Yamamoto, S. ApJ, 617, 399 (2004).
[2] Hirota, T., & Yamamoto, S. ApJ, 646, 258 (2006).
[3] Tafalla, M., & Santiago, J. A&A, 414, L53 (2004).
[4] Suzuki, H., Yamamoto, S., Ohishi, M., Kaifu, N., Ishikawa, S., Hirahara, Y., &Takano, S. ApJ, 392, 551 (1992).
[5] Hirota, T., Ohishi, M ., & Satoshi, Y. ApJ, 699, 585 (2009).

Nobeyama 45 m telescope legacy project: Line survey
Takano, S. (NRO/GUAS), Aikawa, Y. (Kobe U.), Chen, V. (NTHU), Hirano, N. (ASIAA),
Hirota, T. (NAO), Kamegai, K. (Tokyo U. Sci.), Kobayashi, K. (Toyama U.), Kohno, K. (U.
Tokyo), Kuan, Y-J. (NTNU), Liu, S.-Y. (ASIAA), Nakajima, T. (Nagoya U.), Ohashi, N.
(NAO), Ohishi, M. (NAO), Ozeki, H. (Toho U.), Sakai, N. (U. Tokyo), Sakai, T. (U. Tokyo),
Shiba, S. (U. Tokyo), Su, Y.-N. (ASIAA), Sugimura, M. (U. Tokyo), Takakuwa, S. (ASIAA),
Umemoto, T. (NAO), Wang, K.-S. (U. Leiden), Watanabe, Y. (U. Tokyo), Yamada, M.
(ASIAA), Yamaguchi, T. (U. Tokyo), Yamamoto, S. (U. Tokyo), Zhang, Q.-Z. (CfA)
Line surveys are of fundamental importance in astronomy not only for complete
understanding of molecular abundances, but also for finding out new observational tools(spectral lines) probing interstellar medium. We carried out a new line survey project at the 3mm region. The new wide band system (2SB receivers, 4-8 GHz IF lines, 3 bit 4 GHz
sampling AD converters, and 2 GHz band width x 16 spectrometers) was used in the latestage of the survey, and the survey speed was accelerated. The target sources are the lowmass star-forming region in L1527, the shocked region in L1157 B1, the infrared dark clouds
G28.34+0.06, and the external galaxies NGC 1068, NGC 253, and IC 342. The main results
are as follows.
(1) L1527: This is an interesting star-forming region with high abundances of carbon-chain
molecules [1]. The survey from 80 to 117 GHz has been completed. We detected many lines
from 39 species including various carbon-chain molecules, isotopic species (D, 13C) of somecarbon-chain molecules, and unidentified species. In particular, we detected the lines ofcyclopropenone and propynal as well as those of cyclic-C3D2 and 13C substituted cyclic-C3H2.
(2) L1157 B1: This is a prominent region of interactions between a molecular outflow fromthe protostar and ambient clouds [2, 3]. This is an ideal region to study shock chemistry. The
survey was finished from 78.1 to 115.5 GHz. We detected 130 lines from 44 species including
CH3CHO, CH2DOH, carbon-chains, and PN [4, 5, 6].
(3) G28.34+0.06 (possible high-mass star-forming regions): Three interesting positions called
MM1, MM4, and MM9 were selected, and the survey almost covered from 80 to 110 GHz.
Toward MM1 and MM4 line wings were found in SiO and so on. These wings indicate
outflow activities. In addition, CH3CHO was detected only in MM1 and MM4, though N2D+
was detected only in MM9. Based on these results, MM1 and MM4 are thought to be active
and more evolved objects.
(4) NGC 1068 is a nearby galaxy with X-ray radiation from the active galactic nucleus, andNGC 253 and IC 342 are also nearby galaxies with prototypical starbursts. The survey was
finished from 85 to 116 GHz. We detected 21-23 species depending on the galaxies including
several new detections (e.g. cyclic-C3H2 and C2H in NGC 1068 [7]). The intensities of HCN
and CN relative to 13CO are significantly strong in NGC 1068 compared to those in NGC 253
and IC 342.
References
[1]
[3]
[5]
[7]

Sakai et al. 2008, ApJ 672, 371.
Mikami et al. 1992, ApJ 392, L87.
Yamaguchi et al. 2011, PASJ 63, L37.
Nakajima et al. 2011, ApJ 728, L38.

[2]
[4]
[6]

Umemoto et al. 1992, ApJ 392, L83.
Sugimura et al. 2011, PASJ, 63, 459.
Yamaguchi et al. PASJ in press.

Spectral-Line Surveys at mm and submm Wavelength
toward Outflow-Shocked Region, OMC2-FIR4
Y. Shimajiri,1,2 R. Kawabe,2,3 ,Y. Kitamura4, M. Momose5, T. Tsukagoshi5, M. Saito2,3, and F.
Nakamura2
1

Nobeyama Radio Observatory, 2National Astronomical Observatory of Japan, 3Joint ALMA
Observatory, 4Japan Aerospace Exploration Agency, 5University of Ibaraki

Enormous progress has been achieved in the past few decades in studying the chemicalcomposition of dense molecular gas associated with star-forming regions. The chemicalcomposition and evolution in the dense interstellar medium themselves are of particular greatinterest. In addition, they are very useful for the diagnostics of protostar or protoplanetary
disk evolution, also of interstellar shocks. Shock chemistry is one of keys to understandchemical compositions of interstellar medium because shock waves are ubiquitous. Shockchemistry is, however, still obtained in protostellar outflows and jets, although many
theoretical studies have been extensively made since 1980’s [1][2].
OMC2-FIR4(d=400pc) is one of the most suitable targets to investigate the shockchemistry, because the NMA(Nobeyama Millimeter Array) and ASTE(Atacama
Submillimeter Telescope Experiment) observations have revealed that the FIR3 outflow
interacts with the dense gas associated with FIR4 on the basis of the following three pieces ofevidence [3]. The first is morphological one that the distribution of the southern lobe of the
FIR3 outflow coincides with that of the FIR4 dense gas. The second is chemical one that theemission of the shock tracers of SiO and CH3OH is distributed at the tip of the outflow. The
third is kinematical one that the increment in the velocity width of the H13CO+, SiO,
CH3OH, and CO lines is seen at the interface between the outflow and the dense gas.
To obtain more evidence for the shock chemistry in FIR4, we have completed 3-mm
(82-106GHz) and 850-μm (335-355GHz) line surveys of FIR4 (i.e., the southern lobe of
FIR3 outflow) as well as FIR3 and FIR3N (the northern lobe) using the NRO 45m and ASTE
telescopes. FIR4 is proved chemically enriched remarkably. Our 3-mm and 850-μm line
surveys detected 122 lines and 21 species including CH3CCH and C3H2 as well as S-bearing
molecules such as H2CS and SO. First, we found that line profiles of CH3OH, and SO
consists of two components with narrow (<3km/s) and wide (>3km/s) velocity widths, andthe wide-velocity components are detected only at the outflow-shocked region, FIR4, as wellas the emission of SiO, a typical shock tracer. These facts strongly suggest that the CH3OH,
SO, and SiO lines surely trace the shocked gas. Second, the rotational temperatures ofpossible shock tracers are estimated to be as high as 50-150K, suggestive of shock heating. In
contrast, the rotational temperatures of dense gas tracers such as H13CO+, HCN, and HNC
are estimated to be ~20K, which can be considered as the temperature of the quiescent gas.
References[1] McKee, C.F., & Hollenbach, D.J. 1980, ARAA, 18, 219[2] Neufeld, D.A., Lepp, S., & Melnick, G. J. 1995, ApJS,100, 132[3] Shimajiri et al. 2008, ApJ, 683, 255S

Abundant CH3OH in the Cold Starless Core TMC-1

T. Soma,1 N. Sakai,1 Y. Watanabe,1 and S. Yamamoto1
1

Department of Physics, University of Tokyo, Japan

Methanol (CH3OH) is generally abundant in star-forming regions [1][2]. It is thought to be
produced mainly on grain mantles, and is released into the gas phase by various starformation activities. Since its abundance is apparently enhanced in the shocked region such as
L1157B1 [3][4][5], CH3OH is sometimes used as a shock tracer. However, CH3OH ismoderately abundant even in cold starless cores like Taurus Molecular Cloud-1 (TMC-1) (Tk ∼10 K), although no heating sources are embedded there. Since evaporation temperature of
CH3OH is about 100 K, existence of CH3OH in TMC-1 is puzzling. While the production
pathway in the gas phase is proposed [6], it cannot explain the observed abundance of CH3OH
in TMC-1.
Recently, we have conducted high velocity-resolution observations of CH3OH in TMC-1. We
have found that the line shape of CH3OH is much different from those of other carbon chain
molecules to- ward TMC-1(Cyanopolyyne Peak; CP), which indicates different distribution ofthese two species in the core. We have also conducted mapping observations of CH3OH(Jk =2k −1k), C34S(J = 2−1) and C18O(J =2−1) in the 150”×150” area around TMC-1(CP), andrevealed that the distribution of CH3OH is anticorrelated with that of C34S. This difference
would be an important clue to understand the mechanism for production of CH3OH in TMC-1.
We are considering two possible mechanisms for desorption of CH3OH from grain mantles instarless cores. One is soft shock caused by collisions of small clumps inside the core and/or
accretion motions of envelope materials onto the core, whereas the other is desorption bycosmic-ray induced UV. In any case, the distribution of CH3OH would not follow the
distribution of the dense gas (CS), being consistent with our observation. It therefore seems
likely that the molecular composition in the gas phase would significantly be affected by nonthermal desorption processes of grain mantles in starless cores.

References
[1]
[2]
[3]
[4]
[5]
[6]

Geoffrey A. Blake et al., 1987, ApJ, 315, 621.
van Dishoeck, Ewine F. et al., 1995, ApJ, 447, 760.
L. W. Avery and M. Chiao, 1996, ApJ, 463, 642.
R. Bachiller and M. Pérez Gutiérrez, 1997, ApJ, 487, L93 .
B. Nisini et al., 2010, A&A, 518, L120.
van der Tak, F.F.S. et al., 2000, A&A, 361, 327.

Developments of Optical Spectrometers as Approaches to
Diffuse Interstellar Bands
M. Araki, S. Uchida, K. Niwayama, K. Abe, and K. Tsukiyama
Faculty of Science Division I, Tokyo University of Science, JapanThe diffuse interstellar bands (DIBs) were first discovered in the optical absorption
spectra on stars in 1922. Although several hundreds DIBs were detected already, DIBs
still remain the longest standing unsolved problem in spectroscopy. It has not been
known that what kind molecules have these absorptions. One of the best approaches to
identify DIBs can be the following procedure: 1) a generation of a DIBs candidate
molecule in laboratory, 2) measurements of laboratory frequencies of electronictransitions of the molecule, and 3) comparisons between the laboratory frequencies andastronomically observed DIBs spectra.
To be able to solve the DIBs problem, we have been developed a discharge-emission
spectrometer. A hollow cathode was used to generate molecular ions in a discharge,
since it has been suggested that molecular ions can be probable DIBs candidates. The
discharge was produced by a pulsed voltage of 1500V. A wide wavelength range of thisspectrometer was covered by a monochromator HORIBA Jobin Yvon iHR320 (the 200800 nm wavelength range using three gratings having groove densities 1200 and 1800
gr/mm). The dispersed discharge-emission was detected by a photomultiplier andrecorded via a lock-in amplifier. Recently the 2E2–X2B3 electronic transition of thebutatriene cation H2CCCCH2+ was observed in the discharge emission by using 2butyne CH3CCCH3 as shown in Figure 1. The frequency of the electronic transition wasmeasured to be 20380 cm-1, which make a study of a comparison with the observed
DIBs spectrum.
Although the above spectrometer can cover the wide wavelength range, the resolution is
insufficient to have an accurate comparison between the laboratory frequencies andastronomically observed DIBs spectra. Since DIBs are absorption, an absorption
spectrum in laboratory is better suited for the comparison. To obtain a high-resolution
absorption spectrum, a cavity ringdown spectrometer using the same hollow cathode isunder development.
HC4H+
H2CCCCH2+

Figure 1: Emission Spectrum of H2CCCCH2+ observed by the discharge-emission spectrometer(left) and the molecular structure of H2CCCCH2 (right).

Rotational spectra of methyl formate in the new vibrational excited states
Y. Sakai1 K. Kobayashi,1 M. Tsukamoto2 M. Fujitake2 N. Ohashi212Faculty of Science, Univ. of Toyama, Japan
Grad School of Natural Sci. and Tech., Kanazawa Univ., JapanThe methyl formate molecule (HCOOCH3) is a typical example of the molecule with highspectral density found in interstellar space. So far, many transitions were found in hot cores inmassive star-forming regions and recently, were also found in very young low mass starforming regions. We have also identified in its first and second torsional excited state in Orion
KL. [1][2] _The observed intensity suggests the possible detection of transition of thismolecule in the higher vibrational state. The methyl formate has several low-lying vibrational
states. Figure 1 shows the fundamental band below 500 cm-1 as well as the excited state of theCH3 torsion (internal rotation).
The microwave spectral data below 200 GHz were taken at the University of Toyama.
Additional measurements including the date below and above 200 GHz have also been carriedout. All the date was used to search for the excited state with the aid of the computer program
developed at Kanazawa University.
We have assigned series of lines in the two new vibrational excited states. The relative energy
to the ground state estimated from the spectral intensities was determined. Based on the
results, it is possible that one is COC deform or Skeletal torsion, and another is combination
band COC deform or skeletal torsion with internal rotation.

-1

Figure 1: Vibrational energy level of HCOOCH3 (~500 cm ). Red colored energy levels are abinitio MO by Dr. Senent.[3] Black colored energy levels are experiment.[4]References
[1]
[2]
[3]
[4]

K. Kobayashi, K. Ogata, S. Tsunekawa, S. Takano. 2007, ApJ, 657, L17
S. Takano, Y. Sakai, S. Kakimoto, M. Sasaki, K. Kobayashi. 2012, PASJ. 64. 89
M. L. Senent, M. Villa, F. J. Melendez, R. Dominguez-Gomez. 2005, ApJ, 627,567
T. Shimanouchi, J. Phys. Chem. Ref. Data, 1, 189-216 (1972)

Sub-millimeter Spectroscopic study for detection of pre-biotic molecules
in interstellar space
Y. Motoki,1 H. Ozeki,1 and K. Kobayashi2
1

Department of Environmental Science, Toho University, Japan2
Department of Physics, University of Toyama, Japan

Among the biologically important molecules, glycine (NH2CH2COOH) is the simplest aminoacid. Astronomical searches for glycine have continued up to present.1 But glycine have notdetected in interstellar space but for chondrite meteorite. In addition origin of glycine andothers amino-acid is yet unknown. In this study, we focusd Strecker synthesis,
NH3+H2CO→CH2NH+H2O,
CH2NH+HCN→NH2CH2CN,
NH2CH2CN+ H2O→NH2CH2CONH2,
NH2CH2CONH2+H2O→NH2CH2COOH+NH3,
one of the famous reaction that produce amino acid. In this synthesis, methylenimine (CH2NH,
in short MI) and Amino-acetonitrile (NH2 CH2NH in short AAN) are precursors of glycine. 2
In our experiments, we measured pure rotational spectra of MI, this isotope 13CH2NH andCH215NH up to 1.2 THz, and AAN up to 1.2 THz to carry out with frequency-modulated submillimeter wave spectrometer.
Analysis has been done with Watson’s S reduced Hamiltonian. The detailed molecularconstants will be reported.

Figure 1: The spectrum of AAN in the 486GHz region.

References[1][2]

Kuan, Y .-J., et al. ApJ. 593, 848, (2008) etc.
Ugliengo, P., Rimola, A. & Sodupe, M. Rend. Fis. Acc. Lincei., 22, 137, (2011).

Phosphorous chemistry in the shocked region L1157 B1
T. Aota1 and Y. Aikawa1
1

Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501,Japan

Since shock waves are ubiquitous in interstellar space, a thorough understanding of shockchemistry is important to interpret observed chemical composition. This is particularly true
for star-forming regions. For example, outflow gases from protostar bring on shock waves
due to collision with surrounding gases.
L1157 dark cloud harbors a low-luminosity Class 0 protostar, which drives a well-collimatedmolecular outflow. L1157 B1 is a shocked region formed by an interaction between themolecular outflow and ambient gas. Since the B1 position is spatially apart from the protostar,the "pure" shock chemistry can be investigated. Because of this reason, many observational
studies are conducted to investigate physical and chemical condition [1] [2] .
Very recently, Yamaguchi et al. (2011) reported detection of PN for the first time in theL1157 B1 and B2 shocked region. The abundance relative to H2 is estimated to ben(PN)/n(H2) = (2-6) × 10-10 towards B1 and (3-7) × 10-10 towards B2 [3]. More recently, a
subsequent work (Yamaguchi et al. in prep) reported that PO is not detected at shocked
region; the upper limit of PO abundance relative to H2 is 2.5 × 10-10 . Chemistry of P-bearing
species has been investigated in the pseudo-time dependent model. For example, Charnley &Millar (1994) investigated P-chemistry in the hot core model, in which they assumed aconstant warm temperature (100K-300K) and high density (2.0 ×107 cm-3) , and showed thatPN can be produced enough to be observed [4]. But shock chemistry calculations that
especially focus on p-bearing species have not been conducted.
In this work, we study the evolution of the P-bearing species in a 1D C-shock model.
Temporal variations of physical parameters (density and temperature) are adopted from
Jimenez-Serra et al. (2008) [5]. We found that observed abundance of PN can be reproduced
in a C-shock model with v=20km s-1, n=2.0 × 104 cm-3 , only if the N atom abundance ishigh(n(PN)/n(H) ~ 10-5 ) in the pre-shock gas.

References
[1]
[2]
[3]
[4]
[5]

Bachiller, R., & Perez Gutierrez, M. 1997, ApJ, 487, 93
Arce, H.G., Santiago-Garcia, J., Jorgensen, J.K., Tafalla, M., Bachiller, R. 2008, ApJ, 681, 21
Yamaguchi, T., Takano, S., Sakai, N. et al. 2011, PASJ, 63, 37
Charnley, S.B., & Millar, T.J. 1994, MNRAS, 270, 570
Jimenez-Serra, I., Caselli, P., Martin-Pintado, J., Hartquist, T.W. 2008, A&A, 482, 549

Can Thermal Instability Grow behind a Shock Wave in HI and Molecular Clouds?
T. Aota,1 T. Inoue,2 and Y. Aikawa1
1

2

Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501,Japan.
Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Chuou-ku,
Sagamihara 252-5258, Japan

Thermal instability is an important physical process to determine the structure in theinterstellar medium. It is widely known that low and mid-temperature parts of the interstellar
medium (ISM) is consist of warm and cold neutral medium (WNM and CNM) [1]. Field,
Goldsmith & Habing (1969) calculated the thermal equilibrium state. They showed that there
are three physical states under the pressure equilibrium: two stable states of CNM and WNM
and one unstable state [2].
The thermal instability is considered to be the origin of the tiny scale structures which havebeen detected HI gas [3] and molecular cloud [4] [5]. Many authors have studied the
dynamical condensation (fragmentation) process of the ISM driven by thermal instability inthe shocked layer of WNM. Koyama & Inutsuka (2002) show that tiny clumps of CNM areformed as a result of thermal instability in the layer compressed by shock propagation [6] .
Recently, Inoue & Inutsuka (2008, 2012) studied the analogous process, including the effectof the magnetic field, and showed the generation of sheetlike HI clouds and molecular cloud[7] [8] .
While the thermal instability in the condensation process of WNM to CNM have been studied
intensively, its role in CNM and the molecular clouds has not yet been examined. Because theinterstellar clouds are known to be always turbulent with supersonic velocity dispersion [9][10], detailed study of the effect of thermal instability in the shocked cloud must be explored.
Using 1D hydrodynamics simulations with the effects of detailed cooling, heating andchemical processes, we examine thermal stability of shocked gas in HI and molecular clouds.
We also estimate the e-folding time of the thermal instability to obtain the degree of
perturbation grow in shocked gas. We find that both HI clouds and molecular clouds can bethermally unstable in the cooling layer behind the shock wave. Seed density perturbations in
HI cloud can grow exp(5)~150 times larger than the initial state, while perturbations inmolecular cloud can grow roughly exp(1)~2.7 for high Mach number shock. These results
suggest that, in order to discuss fine structures in the clouds, the isothermal approximation
may not adequate in CNM and molecular cloud.
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]

Heiles, C., & Troland, T.H. 2003, ApJ, 586, 1067
Field, G.B., Goldsmith, D.W., & Habing, H.J. 1969, ApJ, 155, 149
Heiles, C. 1997, ApJ, 481, 193
Langer, W.D., Velusamy, T., Kuiper, T.B.H. et al. 1995, ApJ, 453, 293
Sakamoto, S., & Sunada, K. 2003, ApJ, 594, 340
Koyama, H., & Inutsuka, S. 2002, ApJ, 564, L97
Inoue, T., & Inutsuka, S. 2008, ApJ, 687, 303
Inoue, T., & Inutsuka, S. 2012, arXiv1205.6217v1
Larson, R.B. 1981, MNRAS, 194, 809
Heiles, C., & Troland, T.H. 2005, ApJ, 624, 773

The influences of disk winds on chemical evolution of protoplanetary disks
D. Ishimoto,1 H. Nomura,1 D. Heinzeller,2 C. Walsh,3 and T. J. Millar,3
1

Department of Astronomy, Graduate School of Science/Kyoto University, Japan
2
Meteorological Service of New Zealand Ltd, New Zealand
3
Astrophysics Research Centre, School of Mathematics and Physics/Queen’s University
Belfast, UK

In the past 20 years, several molecules, molecular ions and radicals have been detected fromplotoplanetary disks thanks to the improvement of observational facilities. More species will
be detected by ALMA which has high sensitivity and spatial resolution. So, theoretical studyof chemical structure of plotoplanetary disks is required in order to understand detailed
chemical and physical structure of the disks from the detected molecular lines.
In this study, we calculate the chemical evolution of plotoplanetary disks considering disk
winds driven by MRI turbulence and investigate the influences of disk winds on chemical
structure of disks. As a result of our calculations, abundances of some molecules increase at
the boundary between intermediate and upper layers. It is because molecular hydrogen istransferｒed into hot layer where molecules such as OH, H2O, and then HCN are produced
via endothermic gas-phase reactions with H2. We also calculate molecular line emission andvelocity profile, and discuss which lines are affected by disk winds.

References[1][2]

T. Suzuki, & Shuichiro Inutsuka, “DISK WINDS DRIVEN BY MAGNETROTATIONAL
INSTABILITY AND DISPERSAL OF PROTOPLANETARY DISKS”, 2009, ApJ 691, L49 .
D. Heinzeller, H. Nomura, C. Walsh, & T. J. Millar, 2011, ApJ 731, 115 .

From Prestellar to Protostellar Cores:
Time Dependence and Deuterium Fractionation
Y. Aikawa,1 V. Wakelam,2 F. Hersant,2 R.T. Garrod,3 E. Herbst4
1

Department of Earth and Planetary Sciences, Kobe University, Japan2
Univ. Bordeaux, LAB, UMR 5804, F-33270, Floirac, France
3
Department of Astronomy, Cornell University, USA
4
Department of Chemistry, Astronomy, and Physics, University of Virginia
We investigate the molecular evolution and D/H abundance ratios that develop as starformation proceeds from a dense-cloud core to a protostellar core, by solving a gas-grain
reaction network applied to a 1-D radiative hydrodynamic model with infalling fluid parcels.
Spatial distributions of gas and ice-mantle species are calculated at the first-core stage, and attimes after the birth of a protostar. Gas-phase methanol and methane are more abundant than
CO at radii r < 100 AU in the first-core stage, but gradually decrease with time, whileabundances of larger organic species increase. The warm-up phase, when complex organic
molecules are efficiently formed, is longer-lived for those fluid parcels in-falling at laterstages. The formation of unsaturated carbon chains (warm carbon-chain chemistry) is also
more effective in later stages; C+, which reacts with CH4 to form carbon chains, increases inabundance as the envelope density decreases.
The large organic molecules and carbon chains are strongly deuterated, mainly due to highD/H ratios in the parent molecules, determined in the cold phase.
We also extend our model to simulate simply the chemistry in circumstellar disks, bysuspending the 1-D infall of a fluid parcel at constant disk radii. The species CH3OCH3 and
HCOOCH3 increase in abundance in 104-105 yr at the fixed warm temperature; both also havehigh D/H ratios.

Figure:Radial Distribution of complex
organic species and carbon chain
species at the first core stage(t= -5.6×10-2 yr), and protostellar
stage (t=4.3×102 yr, and 9.3×
104 yr).

Deuterated water in turbulent protoplanetary disks
K. Furuya,1 Y. Aikawa,1 H. Nomura,2 F. Hersant,3,4 and V. Wakelam3,4
1

2Department of Earth and Planetary Sciences, Kobe University, Japan
Department of Astronomy, Graduate School of Science, Kyoto University, Japan
3
LAB, Univ. Bordeaux, France
4
LAB, CNRS, France

Deuterated water observed in the current solar nebula can provide insights into how water has
evolved in the primitive solar nebula. So far, D/H ratios in cometary water have beenmeasured in seven comets, six from the Oort Cloud (~(3–5)X10-4; e.g., Mumma et al. 2011,
and references therein), one from the Kuiper Belt (~1.6X10-4; Hartogh et al. 2011). In all ofthem, deuterium concentrates by about an order of magnitude relative to the elemental
abundance of deuterium in the interstellar medium (~1.5X10-4; Linsky 2003). A key questionis when this ratio is established during the star and planet formations. Here, we focus on the
protoplanetary disk phase.
Deuterium fractionation in plotoplanetary disks have been studied numerically (e.g., Aikawa& Herbst 1999). Willacy et al. (2009) investigated deuterium chemistry in inner disks (< 30AU) considering the radial accretion. They found that the D/H ratio in water ice in the
midplane retains their initial ratio (~10-2, which set by their dense cloud core model) for 106
yr, since water ice is not destroyed efficiently there. However, we note that turbulent mixing
could change the situation drastically. Oxygen is mainly in atomic form in the disk
atmosphere, while it is in water ice in the midplane (e.g., Bergin et al. 2007, and references
therein). If the turbulence exists, water ice would be transported to the disk atmosphere anddestroyed by photoreactions and/or thermal desorption, while atomic oxygen would betransported to the disk midplane and reform water ice. If such destruction and reformation
processes occur effectively, the D/H ratio in water ice would be lowered or enhanced
depending on the atomic D/H ratio near the disk midplane.
In this presentation, we report the effect of turbulent mixing in the vertical direction on the
D/H ratio of water in protoplanetary disks. We solved the rate equations with diffusion terms,
which mimic the turbulent mixing, adopting the physical model of a disk surrounding atypical T Tauri star (Nomura et al. 2005, 2007). A collapsing core model is calculated to set
the initial molecular abundances of our disk models, in which the D/H ratio in water ice is~10-2. The D/H ratio in water ice in the midplane does not significantly change for 106 yr inthe case of alpha=10-3, while it decreases to ~10-3 at R=10–30 AU in the case of alpha=10-2.
The model ratio remains higher than the cometary ratio. It indicates that in the case of thesolar nebula, the D/H ratio in water might be already much less than 10-2 in the early phase of
the disk.
References[1] Aikawa, Y., & Herbst, E., 1999, ApJ, 526, 314[2] Bergin, E. A., et al. 2007, in Protostars and Planets V, ed. B. Reipurth, D. Jewitt, & K. Keil (Tuscon, AZ:
Univ. Arizona Press), 751[3] Hartogh, P., et al. 2011, Nature, 478, 218[4] Linsky, J. L. 2003, Space Sci. Rev., 106, 49[5] Mumma, M. J., & Charnley, S. B. 2011, ARAA, 49, 471[6] Nomura, H., et al. 2007, ApJ, 661, 334[7] Nomura, H., & Millar, T. J. 2005, A&A, 438, 923[8] Willacy, K., & Woods, P. M. 2009, ApJ, 703, 479

Water formation by OH + H2 on grain surfaces at 10 K: large isotope effects byquantum tunneling
Y. Oba, N. Watanabe, T. Hama, K. Kuwahata, H. Hidaka, and A. Kouchi
Institute of Low Temperature Science, Hokkaido University, Japan
Water (H2O) is the most abundant solid component in icy grain mantles in molecular clouds.
It is widely accepted that grain-surface reactions play a pivotal role for H2O formation in
those environments. One of the representative pathways is the reaction of hydroxyl radicals(OH) with H2 molecules;
OH + H2 → H2O + H, (1)whose activation barrier is about 2100 K in the gas phase [1]. Due to the large barrier, it isunlikely that reaction (1) thermally occurs on the surface of interstellar grains at as low as 10
K; it should proceed through quantum tunneling. However, it remains unknown whether thetunneling surface reaction really occurs at such low temperatures.
In the present study, we performed laboratory experiments on the formation of H2O throughquantum tunneling reaction (1) under astrophysically relevant conditions.
When H2 was codeposited onto a cold (10 K) substrate with OH, which was produced bydissociating H2O in a microwave-induced plasma and cooled down to 100 K, the formation of
H2O was observed in the infrared absorption spectrum of the reaction products.
We next performed similar experiments by using D2 instead of H2 in order to measure isotope
effects on the reaction. If OH react with D2, HDO is formed by the following reaction:
OH + D2 → HDO + D. (2)We found that HDO was actually formed by the codeposition of D2 with OH. However, theefficiency of reaction (2) was about 10% of that of reaction (1) under the same experimental
conditions. The relative efficiency of reactions (1) and (2), as well as that of other reactions
using OH and H2 isotopologues (OD, HD, and D2) was summarized in Figure 1 where thewidth of arrows represent the relative efficiency of each reaction. H-atom abstraction from H2or HD (thick arrows) was more effective than D-atom abstraction from HD or D2 (thinarrows). The observed difference in the reaction efficiency can be explained with a differencein the effective mass of each reaction. Therefore, the strong mass-dependence of reactions
clearly indicates that reaction (1) proceeds through quantum tunneling at 10 K.

OH
H2
H

HD

OD
HD

D H

H2O

D2

H2
D H

HDO

HD

HD

D H

D2
D

D 2O

Figure 1: Schematic illustration of reaction efficiency; thick and thin arrows represent effective and lesseffective reactions, respectively. The relative efficiency is approximated as 1 to 0.1.

References[1]

R. Atkinson et al. 2004, Atmos. Chem. Phys. 4, 1461.

Deuterium fractionation of methylamine through atomic grain-surface reactions at low
temperatures: implication for the possible D/H ratio in molecular clouds
Y. Oba, T. Chigai, N. Watanabe, and A. Kouchi
Institute of Low Temperature Science, Hokkaido University, Japan
Interstellar methylamine (CH3NH2) was first found in 1974 toward Sgr B2 and Ori A [1]. Thisfinding is of interest in view of astrobiology because methylamine could be a precursor ofamino acid in space [2]. Laboratory studies revealed that methylamine can be formed byvarious reactions both in the gas phase and the solid phase in molecular clouds (MCs) [3,4].
In either case, it is likely that the CH3NH2 is retained on icy grains at as low as 10 K and issubjected to various processes on them.
Deuterium (D) fractionation of interstellar molecules is an important issue when consideringchemical evolution in MCs. Previous studies revealed that atomic grain-surface reactions playa significant role for the D enrichment of interstellar molecules such as CH3OH [5] and H2CO
[6]. Although D-substituted methylamine has never been observed, it is reasonable to consider
that interstellar methylamine is deuterated to some extent. In the present study, we performedlaboratory experiments on the hydrogen (H)-D and D-H substitution reactions of solid
methylamine through atomic-surface reactions at low temperatures. Based on the obtained
experimental results, we estimated a possible D/H ratio of methylamine brought by atomicsurface reactions in MCs.
When solid CH3NH2 was exposed to D atoms at 10 K, deuterated methylamine CD3ND2 wasproduced. Then we measured the rate of the H-D substitution at the functional group level byusing partly deuterated methylamines CD3NH2 and CH3ND2; the H-D substitution rate ofmethyl group was about 10 times larger than that of amino group and on the same order withthat of methanol [5]. When deuterated methylamine CD3ND2 was exposed to H atoms at 10 K,hydrogenated methylamine CH3NH2 was produced. D-H substitution rate of methylamine wasalso measured at the functional group level: 0.4 for the methyl group and 0.1 for the aminogroup relative to the H-D substitution rate of methyl group.
Based on the measured H-D and D-H substitution rates of methylamine, we calculated timevariations in the fractional abundances of methylamine isotopologues brought by atomic
surface reactions in MCs. Assuming that only CH3NH2 is present at time t = 0, atomic D/H =0.01, and n(H) = 1 cm-3, about 3% of CH3NH2 is converted into deuterated methylamines at t
= 106 years where the typical lifetime of MCs. Among deuterated methylamines, CH2DNH2 isthe most abundant, followed by CH3NHD. The singly-deuterated methylamines compriseabout 97% of total deuterated methylamines.
The present study proposes that deuterated methylamines are possibly present in MCs,
although their absolute abundances may not be large. Future astronomical observations with
better S/N are highly desired for the detection of deuterated methylamines.
References
[1]
[2]
[3]
[4]
[5]
[6]

N. Kaifu, et al. 1974, ApJ 191, L135.
P. D. Holtom, et al. 2005, ApJ 626, 940.
E. P. Gardner & J. R. McNesby 1980, J. Photochem. 13, 353.
P. Theule, et al. 2012, A&A 534, A64.
A. Nagaoka, N. Watanabe, & A. Kouchi, 2007, J. Phys. Chem. A 111, 3016.
H. Hidaka, M. Watanabe, A. Kouchi, & N. Watanabe, 2009, ApJ 702, 291.

The surface diffusion mechanism of hydrogen atom on interstellar ice
K. Kuwahata1, T. Hama1, N. Watanabe1 A, Kouchi1, Y, Kimura1
1

Institute of Low Temperature Science, Hokkaido University, Japan

It has been recognized that the abundance of some important molecules, including H2, H2O
and NH3, cannot be explained by pure gas-phase formation, and that surface reactions on dust
grains are crucial to explain the production of those molecules. Molecular formation on ASW
proceeds via elementary processes of reactants: adsorption, diffusion, and reaction withanother absorbed reactant. Since in cold and dense clouds dust grains are covered withamorphous solid water (ASW), the diffusion of H atoms on ASW is of significant importancefor the surface reactions. For the diffusion mechanism of H atom on ASW, quantum tunnelingand thermal hopping are often advocated [1]. However, there have been no experimental
reports on the diffusion mechanism of H-atom on ASW. Recently, Watanabe et al. (2010)
presented the results of a novel type of experiment to shed light on the longstanding dispute
about the activation energy of H atom diffusion on ASW [2]. They performed direct detectionof H atoms adsorbed on ASW using photostimulated desorption (PSD) and resonanceenhanced multiphoton ionization (REMPI). In the present study, we extended this method tomeasure the diffusion of deuterium atom on ASW. From the isotope effect of surface
diffusion, we discuss the diffusion mechanism of H atom on ASW [3].

1.2

(a)

1.0
0.8
0.6
0.4
0.2
0.0
-10

0

10 20 30 40 50 60 70 80 90 100

Waiting time after H atom deposition / minD signal intensities / arb. units

H signal intensities / arb. units

The figure shows the time variations of the signal intensities of H and D atoms (IH and ID)
photodesorbed from ASW at 8 K as a function of the waiting time, t, after the deposition of
atoms. Our another experiment found out that monoatomic desorption from ASW plays only aminor role, and the attenuations of IH and ID on the ASW surface after atomic deposition arethus caused mainly by recombination of the atoms following diffusion. Both IH and ID
decrease at a similar rate. We derived the activation barriers for the diffusion of H and D
atoms to be 22 and 23 meV, respectively. Since the tunneling effect strongly depends on theparticle mass, thermal hopping better explains the diffusion mechanism rather than tunneling.
1.2

(b)

1.0
0.8
0.6
0.4
0.2
-10

0

10 20 30 40 50 60 70 80 90 100

Waiting time after D atom deposition / minFigure: Attenuation of photodesorption intensities of (a) H atoms and (b) D atoms adsorbed on ASW at 8 K
as a function of the waiting time after a deposition time.

References[1]
A. G. G. M., Tielens, “The Physics and Chemistry of the Interstellar Medium”. (Cambridge University
Press, 2005), p. 107.
[2]
N. Watanabe, Y. Kimura, A. Kouchi, et al. 2010, ApJ 714, L233
[3]
T. Hama, K. Kuwahata, N. Watanabe, et al. 2012, ApJ 757, 185

Photodesorption mechanisms for H2O from the 157 nm irradiationof amorphous solid water at 90 K
A. Yabushita,1 S. Andersson,2 C. Arasa,3 M. Yokoyama,1 T. Hama,4 M. Kawasaki,5C. M. Western,6 M. N. R. Ashfold 6
1

Department of Molecular Engineering, Kyoto University, Japan
SINTEF Materials and Chemistry, Norway and Department of Chemistry, Physical
Chemistry, University of Gothenburg, Sweden
3
Leiden Observatory and Leiden Institute of Chemistry and , Leiden University, The
Netherlands
4
Institute of Low Temperature Science, Hokkaido University, Japan
5
Research Institute for Humanity and Nature, Japan
6
School of Chemistry, University of Bristol, United Kingdom

2

For grains in the cosmic space, the most important desorption mechanism at the edge ofmolecular clouds is photodesorption. The desorption mechanisms for H2O(v=0) discussed in
our previous papers can be grouped into three types [1]; (A) the one that experiences theinitial electronic excitation, (B) expelled as a result of electronic excitation of a neighboring
molecule, or (C) formed by the recombination of photofragments arising from different
photodissociated molecules. Types (A) and (B) are considered to be direct processes, whereas(C) involves secondary processes. Initially, type (A) and (C) mechanisms will involve highinternal energies in the desorbing molecules (due to photoexcitation and recombination,
respectively). Both might thus be expected to favor formation of vibrationally excited H2O
molecules, whereas the type (B) mechanism could well result in desorbed H2O(v=0)
molecules.
In the present work, the photodesorption of H2O(v=0) following 157 nm photoexcitationof amorphous solid water, has been observed. In addition, signals of H+ and OH+ weredetected in the experiments. Measured H+ and OH+ signals were deduced to originate fromdesorbing vibrationally excited water molecules. Two distinct populations were detected, onethat appeared promptly and another that grew in relative importance with increasing
irradiation time. The former was found to have the same translational temperature as
H2O(v=0), Ttrans=1800 K, desorbed by the kick-out mechanism (reactions (1) and (2)) [2, 3].
We considered that the H+ and OH+ (Ttrans=1800 K) component arise by the kick-out ofvibrationally excited H2O molecules, or by prompt geminate recombination of H and OH
photoproducts followed by desorption, or a combination of both mechanisms.
(1)
H2O(ice) + hν → H* + OH,
kick-out
H* + H2O(ice) → H + H2O(gas).
(2)
recombination H + OH → H2O(gas).
(3)
where H* represents a highly translationally excited H photoproduct with a few eV. The
population of H2O formed by reaction (3) had a much hotter translational temperature, Ttrans =10000 K. The time evolution of this component suggests that it probably arises from thesecondary recombination of photoproducts at the surface. In these experiments we might
therefore have observed H2O photodesorption resulting from three distinct mechanisms: kickout, direct recombination, and secondary recombination.
References
[1]
[2]
[3]

S. Andersson et al., 2011, Phys. Chem. Chem. Phys. 13, 15810
T. Hama et al., 2010, J. Chem. Phys. 132, 164508.
A. Yabushita et al., 2009, ApJ 699, L80.

Surface abundance change in vacuum ultraviolet photodissociation of CO2 and H2O
mixture ices
A. Yabushita,1 T. Kinugawa,1 M. Kawasaki,2 T. Hama,3 N. Watanabe 3
1

Department of Molecular Engineering, Kyoto University, Japan
2
Research Institute for Humanity and Nature, Japan
3
Institute of Low Temperature Science, Hokkaido University, Japan

The importance of energetic processes caused by vacuum ultraviolet (VUV)
photoirradiation is known in the cosmic regions, which can directly induce chemical reactionsof the ice mantles. Photoirradiation on pure or mixed ices triggers desorption of atoms,
radicals, or molecules and the desorption dynamics of photofragments are known to besensitive to the adsorption states of the photoirradiated molecules. Therefore, how the surface
composition changes after VUV photoirradiation needs to be investigated in order to develop
detailed modeling of gas–ice interactions including the reactivity of surface reactions.
In the present work, we have measured time-of-flight spectra and rotationally resolved
resonance-enhanced multiphoton ionization (REMPI) spectra of photodesorbed CO species
following 157 nm photodissociation of mixed CO2/H2O (1:4) ice films at 90 K. Two different
deposition gas mixtures were used for the mixed ice preparation to investigate CO2 adsorption
structures on H2O ice. Hot CO(v=0,1, Ttrans=1600 K and Trot=800 K) and cold CO (v=0,
Ttrans=90 K and Trot=150 K) were observed as photodesorbed products, suggesting that the hot
CO comes from CO2 adsorbed atop the water ice surface, while CO2 trapped in the poroussites produces the cold CO component due to an energy relaxation process by collisions
within the mixed ice en route to the vacuum. Photodesorption of OH and O(3PJ) was also
observed, which is predominantly produced from the photodissociation of H2O in the mixture
ice. Formation of the heterogeneous structures from mixed ice films should depend on
photoabsorption cross sections, ice temperatures and photon flux. Since the VUV absorption
cross section of CO2 is smaller than that of H2O in the entire VUV wavelength region, CO2 isless efficiently dissociated than H2O. Actually, the CO(Ttrans=1600 K) intensity increased with
157 nm irradiation time, while CO(Ttrans =90 K) intensity has no appreciable temporal change.
These results indicate an increase of the surface abundance of the CO2 adlayer adsorbed atop
the CO2/H2O mixture ice at 90 K presumably by the preferential H2O photodissociation.
(a)

(b)

Figure 1: Schematic illustration of the distribution of CO2 in CO2/H2O mixture ice, (a) as deposited
before irradiation and (b) after prolonged 157 nm irradiation. CO2 (red) stands for physisorbed CO2 on
the surface, CO2 (blue) are trapped in the pores and CO2 (gray) are buried in the bulk phase.

References[1]
T. Kinugawa, A. Yabushita, M. Kawasaki, T. Hama & N. Watanabe, 2011, Phys. Chem. Chem. Phys. 13,
15785

Laboratory measurements of spin temperature of water molecules from ice
in thermal desorption
T. Hama, N. Watanabe, and K. Kouchi
1Institute of Low Temperature Science, Hokkaido University, JapanH2O contains two protons with nuclear spin of I=1/2, and two nuclear-spin modifications
exist: the ortho (I=1, triplet, parallel nuclear spin) and the para (I=0, singlet, antiparallel
nuclear spin) with statistical weights 2 I + 1. Nuclear-spin temperature (Tspin) is defined as thetemperature that reproduces a given the ortho-to-para ratio (OPR) if in local thermodynamic
equilibrium. The OPR of H2O is equal to 3 in statistical equilibrium, which is achieved attemperatures above ~50 K.
Tspin of H2O molecules is often observed in comet coma and in star forming regions toinvestigate these molecules' physical and chemical histories. In cometary coma, Tspin of H2O
molecules has been derived to be ~30 K [1]. These values have been implicated as thetemperature of cold grains at molecular condensation or formation in a molecular cloud, or in
the solar nebula [2]. However, the real meaning of the observed Tspin remains a topic ofcontinuing debate.
The present study experimentally measured the Tspinof H2O thermally desorbed from amorphous solid
water (ASW) deposited at 8 K. The experiment was
performed with the RASCAL apparatus at Inst. of
Low Temp. Sci., which consists of a vacuum sample
chamber, and a laser system. ASW was prepared ona Al substrate at 8 K by vapor-deposition in thevacuum chamber, and then heated to 150 K to
sublime H2O. The thermally desorbed H2O
molecules were analyzed ro-vibrationally by theresonanceenhancedmultiphoton
ionization Figure 1. (a) (The black line) 2+1 REMPI(REMPI) method [3]. We also produced ASW at 8 K spectrum of thermally desorbed H2O fromby photolysis of a CH4/O2 mixture (photoproduced vapor-deposited ASW. (The red line) The
ASW) for the idea that Tspin of H2O molecules may best-fitting simulations with Trot = Tspin = 150
relate to formation processes on cold dust grains. K. Indications (JKa,Kc) are rotational
Figure 1 shows the REMPI spectrum of desorbed assignments in H2O. H2O molecules with (Ka+ K = odd) are ortho, while those with (Ka +H2O for the vapor-deposited ASW. The spectrum K =c even) are para species (italic transitions).
c
was best reproduced by the simulation with Trot = (b) Reference simulations with Tspin = 150 K
Tspin = 150 K, where Trot represents rotational (red) and 8 K (blue). Trot is fixed at 150 K.
temperature. Thermally desorbed H2O moleculesfrom the both ice samples showed Tspin almost at the statistical high-temperature limit. These
results suggest that the Tspin of gaseous H2O molecules thermally desorbed from ice does notnecessarily reflect the surface temperature at which H2O molecules condensed or formed. We
discuss the possibility of nuclear-spin conversion of H2O in water ice [3].
References
[1]
[2]
[3]

B. P. Bonev et al., 2007, ApJ, 661, L97-L100.
Y. Shinnaka et al., 2010, PASJ, 62, 263-271.
T. Hama et al., 2011, ApJ, 738, L15 (5pp).

Mid-infrared High-resolution Spectrograph for SPICA
Y. Sarugaku1 , N. Kobayashi2 , Y. Ikeda3, 4, H. Kawakita4, K. Enya1, H. Kataza1,
H. Matsuhara1, T. Nakagawa1, Y. Hirahara5, and SPICA pre-project team1

Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Japan
2
Institute of Astronomy, University of Tokyo, Japan3
Photocoding, Japan
4
Faculty of Science, Kyoto-Sangyo University, Japan
5
Graduate School of Environmental Studies, Nagoya University, Japan

We present the status of the development of mid-infrared high-resolution spectrograph for
SPICA, which is a next-generation infrared astronomical mission in space with a cooled 3.0
m telescope [1]. High-resolution spectroscopy in the mid-infrared wavelength range is ofstrong interest. Since numerous rotational-vibration bands of molecules are located in thiswavelength range, spectra of celestial objects and ISMs provide fruitful information on
physical/chemical condition of them. However, in ground-based observation, systematic
observations have been hampered by the strong atmospheric extinction, which limits theobservational wavelength range, and also by the large amount of thermal background, which
reduces the sensitivity in most cases. Therefore high-resolution spectroscopy from space has
been awaited for investigating the mid-infrared wavelength region, but it has not yet beenrealized because the size and the weight of instruments for high-resolution spectroscopy are
so large and so heavy that it is difficult to launch them. SPICA is a precious opportunity to
explore this exciting field. Mid-infrared Camera and Spectrograph (MCS) is proposed for
SPICA [2]. As one function of MCS, we have been developing a high-resolution spectrograph(MCS-HRS) [3].
The goal of MCS-HRS is to achieve a spectral resolution (λ/Δλ) of 20,000-30,000 in the
mid-infrared wavelength. In the latest specification, the wavelength coverage is set to be
12-18 μm, where many organic molecules can be detected but it is hard to access from grounddue to the strong atmospheric extinction. The main observational targets are ISMs,
proto-planetary disks, and comets. The high-resolution capability of the spectrograph enables
not only identifying molecular lines but also kinematic studies in the mid-infrared
wavelengths. Observing the compositional distribution in proto-planetary disks provides
crucial information to understand the formation process of planets. MCS-HRS can shed lighton the material evolution among ISMs - proto-planetary disks - comets (planetesimals), and it
also has possibility to find molecules some of which could be bio-maker.

References
[1]
[2]
[3]

T. Nakagawa et al., 2012, Proc. SPIE, in press.
H. Kataza et al., 2012, Proc. SPIE, in press.
N. Kobayashi et al., 2008, Proc. SPIE, 7010, 701032