bluuebunny/crossref_metadata_2025_split huggingface dataset:
Testing PDR models against ISO fine structure line data for extragalactic sources
Authors: Vasta M. , Barlow M. J. , Viti S. , Yates J. A. , Bell T. A. 
Published: October 2010

AbstractStudies of our own Galaxy and observations of external galaxies have suggested that stellar ultraviolet radiation can ionize vast volumes of a galaxy and that far-ultraviolet radiation impinging on neutral cloud surfaces is responsible for a large fraction of the observed far-infrared (FIR) spectral line emission that cools the gas (Crawford & al. (1985)). Fine structure (FS) emission lines can be used as tracers of nebular conditions such as density, excitation and ionization. By virtue of their different excitation potentials and critical densities, FS emission lines provide an insight into the energetics and chemical composition of the regions from which they originate. The far infrared [C ii]158 μm, [O i]145 μm and [O i]63 μm fine structure emission lines obtained with the Infrared Space Observatory (ISO) from 35 extragalactic sources are examined to investigate the chemical abundances and large scales physical properties of these sources. Line fluxes are compared with a grid of PDR models previously computed using the UCL_PDR code. We overplotted our model predictions against flux ratios from the [C ii]158 μm and [O i]63 μm and 145 μm ISO LWS fluxes. In this section we will only discuss the sensitivity of the ratios to changes in the input parameters. We find that the average radiation field G0 is 60–8 × 102 and the average density nH 104−9 × 104 cm−3. While ionised carbon, because of its ionisation potential, can be found in both neutral gas and ionised gas clouds, species such as ionised nitrogen [N ii], with ionisation potential of 14.53 eV, can arise only from H ii regions. The 11 sources that have detections of both [C ii] 158 μm and [N ii] 122 μm have mean and median [C ii]158/[N ii]122 flux ratios of 10.2 and 5.9 respectively. A H ii region [C ii]158/[N ii]122 ratio of 1.6 implies that H ii region contribute only 16% (mean case) and 27% (median case) of the overall [C ii] 158 μm flux that is observed. We used the above predicted H ii region [C ii]158/[N ii]122 ratio of 1.6 along with the observed [N ii] 122 μm fluxes, to correct the observed [C ii] 158 μm flux of these 11 sources for H ii region contributions. We estimate that 10-60% of the [C ii] is excited in ionised regions. When accounting for the contribution to the [C ii] 158 μm by H ii regions we found that our models fitted better the observations. We modeled the oxygen emission line profile emitted from an ensemble of PDRs and found a clear [O i] 63 μm self-absorbed profile. We estimate that approximately 20-70% of the [O i] 63 μm intensity may be suppressed through oxygen self-absorption depending on the physical parameters of the PDR regions. This work has been submitted for publication to MNRAS, Vasta et al. (2009).
Mid-IR Spectroscopy of Submm Galaxies: Extended Star Formation in High-z Galaxies
Authors: Menéndez-Delmestre K. , Blain A. W. , Smail I. , Alexander D. M. , Chapman S. C. , Armus L. , Frayer D. , Ivison R. J. , Teplitz H. 
Published: October 2010

AbstractUltra-luminous infrared galaxies (ULIRGs; L > 1012 L⊙) are quite rare in the local universe, but seem to dominate the co-moving energy density at z > 2. Many are optically-faint, dust-obscured galaxies that have been identified only relatively recently by the detection of their thermal dust emission redshifted into the sub-mm wavelengths. These submm galaxies (SMGs) have been shown to be a massive objects (M* ~ 1011 M⊙) undergoing intense star-formation(SFRs ~ 102 − 103 M⊙ yr−1) and the likely progenitors of massive ellipticals today. However, the AGN contribution to the far-IR luminosity had for years remained a caveat to these results. We used the Spitzer Infrared Spectrograph (IRS) to investigate the energetics of 24 radio-identified and spectroscopically-confirmed SMGs in the redshift range of 0.6 < z < 3.2. We find emission from Polycyclic Aromatic Hydrocarbons (PAHs) – which are associated with intense star-formation activity – in >80% of our sample and find that the median mid-IR spectrum is well described by a starburst component with an additional power-law continuum representing < 32% AGN contribution to the far-IR luminosity. We also find evidence for a more extended distribution of warm dust in SMGs compared to the more compact nuclear bursts in local ULIRGs and starbursts, suggesting that SMGs are not simple high-redshift analogs of local ULIRGs or nuclear starbursts, but have star formation which resembles that seen in less-extreme star-forming environments at z ~ 0.
Dust production in supernovae: the case of Kepler's SNR
Authors: Reynoso E. M. , Gomez H. L. , Dunne L. 
Published: October 2010

AbstractWe compare the submillimetre (submm) emission with the Hi and CO distribution towards Kepler's supernova remnant (SNR), and conclude that 0.1 to 1.2 M⊙ of dust originates from Kepler. Such rates are sufficient to explain the origin of dust in high redshift galaxies.
Role of Magnetic Fields in Star Formation
Authors: Crutcher Richard M. 
Published: October 2010

AbstractI describe two recent projects to test star formation theory using Zeeman observations. First, using Bayesian analysis, the probability distribution function of the magnitude of the total magnetic field strength Bt and its dependence on volume density n(H) were inferred from Zeeman observations of the line-of-sight strengths Bz. The result was that from one molecular cloud to another Bt ranges uniformly between values close to zero and a maximum B0, and that B0 scales as n2/3. Second, observations of the ratio of the mass/flux (M/Φ) between the core and envelope regions of four dark clouds yielded values < 1. All of these results disagree with predictions of the strong magnetic field, ambipolar diffusion driven theory of star formation.
Magnetic Fields and Cosmic Rays in Galaxy Clusters
Authors: Dolag Klaus 
Published: October 2010

AbstractIn galaxy clusters, non-thermal components such as magnetic field and high energy particles keep a record of the processes acting since early times till now. These components play key roles by controlling transport processes inside the cluster atmosphere and beyond and therefore have to be understood in detail by means of numerical simulations. The complexity of the intra cluster medium revealed by multi-frequency observations demonstrates that a variety of physical processes are in action and must be included properly to produce accurate and realistic models. Confronting the predictions of numerical simulations with observations allows us to validate different scenarios about origin and evolution of large scale magnetic fields and to investigate their role in transport and acceleration processes of cosmic rays.
BICEP: a cosmic microwave background polarization telescope at the South Pole
Authors: Takahashi Yuki D. 
Published: October 2010

AbstractBicep was a telescope designed to probe the polarization of the cosmic microwave background (CMB) for the signature of gravitational waves produced during the epoch of inflation. The instrument was developed by a team of scientists from Caltech/JPL, UC Berkeley, and UC San Diego. It was installed at the South Pole in November 2005 and the CMB observations were conducted from February to November each year with one winter-over scientist responsible for operating and maintaining the instrument. Taking advantage of the excellent atmospheric conditions at the South Pole, we mapped 2% of the sky at 100 and 150 GHz. We completed 3 years of observations from 2006 to 2008, mapping the CMB polarization anisotropy at degree angular scales with unprecedented sensitivity. In 2010, a next generation instrument, Bicep2, will be installed on the existing telescope mount for an even deeper survey.
The PLATO observatory: robotic astronomy from the Antarctic plateau
Authors: Ashley M. C. B. , Allen G. , Bonner C. S. , Bradley S. G. , Cui X. , Everett J. R. , Feng L. , Gong X. , Hengst S. , Hu J. , Jiang Z. , Kulesa C. A. , Lawrence J. S. , Li Y. , Luong-Van D. M. , McCaughrean M. J. , Moore A. M. , Pennypacker C. , Qin W. , Riddle R. , Shang Z. , Storey J. W. V. , Sun B. , Suntzeff N. , Tothill N. F. H. , Travouillon T. , Walker C. K. , Wang L. , Yan J. , Yang H. , York D. G. , Yuan X. , Zhang X. , Zhang Z. , Zhou X. , Zhu Z. 
Published: October 2010

AbstractPLATO is a 6 tonne completely self-contained robotic observatory that provides its own heat, electricity, and satellite communications. It was deployed to Dome A in Antarctica in January 2008 by the Chinese expedition team, and is now in its second year of operation. PLATO is operating four 14.5cm optical telescopes with 1k × 1k CCDs, a wide-field sky camera with a 2k × 2k CCD and Sloan g, r, i filters, a fibre-fed spectrograph to measure the UV to near-IR sky spectrum, a 0.2m terahertz telescope, two sonic radars giving 1m resolution data on the boundary layer to a height of 180m, a 15m tower, meteorological sensors, and 8 web cameras. Beginning in 2010/11 PLATO will be upgraded to support a Multi Aperture Scintillation Sensor and three AST3 0.5m schmidt telescopes, with 10k × 10 CCDs and 100TB/annum data requirements.
Photoabsorption of hydrocarbons in Titan's atmosphere
Authors: Magalhães Fabíola P. , de Souza Gerardo G. B. , Boechat-Roberty Heloisa M. 
Published: October 2010

AbstractTitan, the largest satellite of the planet Saturn, has a thick atmosphere which consists of nitrogen (N2) and methane (CH4). In 2004, the Cassini-Huygens mission observed the occultation of two stars through the atmosphere of Titan and measured ultraviolet (UV) absorption spectra. Through these spectra it was possible to identify the molecular species contained in this environment. In the present work, we have simulated a spectrum of this atmosphere using some molecules such as CH4, C2H2, C2H4, C2H6, C4H2, and C6H6. Our cross sections data were experimentally obtained using the electron energy-loss technique, where the electron energy-loss spectra, measured high incident energies and in small scattering angles, are similar to photoabsorption spectra. The comparison of our synthetic spectrum with that measured by Cassini shows that this method is very efficient for identifying molecules as well as estimating abundances.
Astrochemistry on the EXPOSE/ISS and BIOPAN/Foton experiments
Authors: Cottin H. , Guan Y. Y. , Coll P. , Coscia D. , Fray N. , Macari F. , Stalport F. , Raulin F. , Szopa C. , Chaput D. , Viso M. , Bertrand M. , Chabin A. , Westall F. , Brack A. 
Published: October 2010

AbstractWe describe three space experiments designed to expose to space conditions, and more specifically to solar UV radiation, selected samples of organic and mineral material.
The detectability of habitable exomoons
Authors: Kipping David M. , Fossey Stephen J. , Campanella Giammarco 
Published: October 2010

AbstractDespite the number of known exoplanets increasing on an almost weekly basis, the question as to whether exoplanets host moons remains unanswered. Exomoons could be potential seats for life, as well as improving our understanding of planetary formation and celestial mechanics. Here we summarize our findings from an investigation into how detectable habitable-zone exomoons are with Kepler-class photometry.
The Gaia astrometric survey
Authors: Sozzetti Alessandro 
Published: October 2010

AbstractIn its all-sky survey, the ESA global astrometry mission Gaia will perform high-precision astrometry and photometry for 1 billion stars down to V = 20 mag. The data collected in the Gaia catalogue, to be published by the end of the next decade, will likely revolutionize our understanding of many aspects of stellar and Galactic astrophysics. One of the relevant areas in which the Gaia observations will have great impact is the astrophysics of planetary systems. This summary focuses on a) the complex technical problems related to and challenges inherent in correctly modelling the signals of planetary systems present in measurements collected with a space-borne observatory poised to carry out precision astrometry at the micro-arcsecond (μas) level, and b) on the potential of Gaia μas astrometry for important contributions to the astrophysics of planetary systems.
Jean Heidmann (1923-2000) and SETI
Authors: Courtin Régis 
Published: October 2010

AbstractJean Heidmann (1923-2000) began his research career as a radio-astronomer in 1959 at Paris Observatory, investigating the structure of galaxies and the distance scale in the nearby universe. In the early 1980's, his scientific interest broadened to the search for extraterrestrial intelligence and he became a strong advocate of SETI, either from the ground or from space.
2D mapping of ice species in molecular cores
Authors: Noble Jennifer A. , Fraser H. J. , Pontoppidan K. M. , Aikawa Y. , Sakon I. 
Published: October 2010

AbstractWe present data from our ice mapping program IMAPE on the AKARI satellite. Initial results show a correlation between the abundance of CO2(s) and H2O(s), consistent with previous studies. We can trace abundances of molecules across a core using a single observation.
Evolution of Young Stars and Their Disks in Serpens
Authors: Oliveira Isa , Merín Bruno , Pontoppidan Klaus , van Dishoeck Ewine 
Published: October 2010

AbstractUnbiased, flux-limited surveys of protoplanetary disks and their parent stars currently exist for only a few clouds, primarily Taurus and IC 348, selected primarily by optical and near-IR data. Such surveys are essential to address questions of disk evolution as a function of stellar parameters such as spectral type, age, accretion activity and environment. Using the ‘Cores to Disks’ (c2d) Spitzer Legacy Program, we discovered a new population of young stellar objects (YSOs) in a region of only 0.8 deg2 in the Serpens Molecular Cloud. This sample contains 150 mid-IR bright (≥ 3 mJy at 8 μm) YSOs with infrared excess, having a broad range of SED types and luminosities. Serpens is therefore a unique target region for obtaining a complete, well-defined sample of multi-wavelength observations of young stars in a possible evolutionary sequence. Compared with other clouds such as Taurus and Chamaeleon, Serpens has an exceptionally high star-formation rate (5.7 × 10−5 M⊙ yr−1). Follow-up complimentary observations in the optical, near- and mid-infrared (Spitzer/IRS GO3) have allowed us to characterize both the central stars and the surrounding disks. The shape and slope of the mid-infrared excess provide information on the flaring geometry of the disks. The spectral features give constraints on grain growth and mineralogy, which in turn probes heating and radial mixing. The presence of PAH features traces UV radiation, whereas Hα and Brγ are used as diagnostics of accretion. Assuming that all stars within a sufficiently small region are nearly coeval, this provides direct constraints on the importance of environment and initial conditions on disk evolution. In this meeting, we have presented our latest results on this rich populations of YSOs, as detailed in Oliveira et al. (2009, 2010). We have discussed connections between the evolution of the disks and that of their harboring stars, and the processes that determine the evolutionary sequence of protoplanetary disks.
The End of Accretion: Transition Disks, Dissipation, and Links to Planet Formation
Authors: Muzerolle James 
Published: October 2010

AbstractI review recent studies of transitional protoplanetary disks, in which the planet forming regions are being cleared of material. The dust and accretion characteristics of these objects as a function of their environment and host star age and mass reveal important clues as to how disk structure is modified and ultimately destroyed. Clearing mechanisms such as grain growth, dynamical interactions with embedded planets or stellar companions, and photoevaporation are likely all involved, pointing to diverse disk evolutionary paths.
Gas Evolution in the Planet-Forming Region of Disks
Authors: Pascucci Ilaria 
Published: October 2010

AbstractThe timescale over which gas-rich disks disperse profoundly affects not only the formation of giant planets but also the habitability of terrestrial planets. In this contributed talk we presented new atomic and molecular diagnostics that can be used to trace the dispersal of gas at disk radii where planets form. We also showed the first observational evidence for photoevaporation driven by the central star and discussed the efficiency of this disk dispersal mechanism.
Observational and numerical tests of jet models in young stars
Authors: Cabrit S. 
Published: October 2010

AbstractJets are found in a wide range of accreting young stars, from brown dwarfs to massive protostars, but their launch region(s) and their role in angular momentum extraction are still debated. Many observational constraints exist on jet properties, including jet widths, kinematics along and across the jet, possible rotation signatures, ejection/accretion ratio, depletion and molecular counterparts. This contribution compares popular models, in particular disk winds, with these constraints and with MHD numerical simulations, highlighting a few open issues.
Are pre-MS stars older than we thought?
Authors: Naylor Tim , Mayne N.J. 
Published: October 2010

AbstractWe present a consistent age ordering for young clusters and groups determined using the contraction of stars through their pre-main-sequence phase. We compare these with ages derived from the evolution of the upper main-sequence stars, and find the upper MS ages are older by a factor 1.5 to 2. We show that increasing the binary fraction and number of equal-mass binaries amongst the O-stars compared to the rest of the MS cannot remove this discrepancy.
Dust and the art of Galactic map making
Authors: Marshall Douglas J. , Joncas Gilles , Jones Anthony P. , Robin Annie C. , Reylé Céline , Schultheis Mathias 
Published: October 2010

AbstractA Galactic model of stellar population synthesis is used along with a genetic algorithm to reconstruct the three dimensional dust distribution in the Milky Way. We have applied this technique towards over 1500 IRDC cloud candidates, for which we recovered distances and masses for 1259 of them. Aside from giving us the distance to the dust, the three dimensional extinction map also provides us with a temperature independent measure of its density. This new method is independent of any kinematical information, thus providing a new way to obtain information on the Galactic distribution of the ISM. It is a good complement to existing measures which are solely based on molecular gas kinematics as both methods are completely independent and both are affected by different systematics. It will be able to provide valuable distance information for use in the analysis and interpretation of far-infrared and sub-millimetre observations by Herschel and Planck. In the future it could be used with deeper stellar observations or observations at longer wavelengths in order to probe even higher density clouds and to even larger distances.
Deducing the Milky Way's Massive Cluster Population
Authors: Hanson M. M. , Popescu B. , Larsen S. S. , Ivanov V. D. 
Published: October 2010

AbstractRecent near-infrared surveys of the galactic plane have been used to identify new massive cluster candidates. Follow up study indicates about half are not true, gravitationally-bound clusters. These false positives are created by high density fields of unassociated stars, often due to a sight-line of reduced extinction. What is not so easy to estimate is the number of false negatives, clusters which exist but are not currently being detected by our surveys. In order to derive critical characteristics of the Milky Way's massive cluster population, such as cluster mass function and cluster lifetimes, one must be able to estimate the characteristics of these false negatives. Our group has taken on the daunting task of attempting such an estimate by first creating the stellar cluster imaging simulation program, MASSCLEAN. I will present our preliminary models and methods for deriving the biases of current searches.
The Statistics and Galactic Properties of the Methanol Multibeam Survey
Authors: Green J. A. , Caswell J. L. , Fuller G. A. , Avison A. , Breen S. L. , Brooks K. , Burton M. G. , Chrysostomou A. , Cox J. , Diamond P. J. , Ellingsen S. P. , Gray M. D. , Hoare M. G. , Masheder M. R. W. , McClure-Griffiths N. M. , Pestalozzi M. , Phillips C. , Quinn L. , Thompson M. A. , Voronkov M. A. , Walsh A. , Ward-Thompson D. , Wong-McSweeney D. , Yates J. A. , Cohen R. J. 
Published: October 2010

AbstractThe methanol multi-beam (MMB) survey has produced the largest and most complete catalogue of Galactic 6.7-GHz methanol masers to date. 6.7-GHz methanol masers are exclusively associated with high-mass star formation, and as such provide invaluable insight into the Galactic distribution and properties of high-mass star formation regions. I present the statistical properties of the MMB catalogue and, through the calculation of kinematic distances, investigate the resolution of distance ambiguities and explore the Galactic distribution.
Virtual Observatory Access to the The IPHAS Data Releases
Authors: Walton N. A. , Drew J. , Gonzalez-Solares E. , Irwin M. J. 
Published: October 2010

AbstractWe highlight the IPHAS Data Releases and how access to the primary data products has been implemented through use of standard virtual observatory (VO) publishing interfaces as provided by the Astro- Grid system. The IPHAS Early Data release (EDR), is a photometric catalogue of more than 200 million unique objects, coupled with associated image data covering more than 1000 square degrees in three colours. These data represent the largest data sets to date published solely through Virtual Observatory interfaces.
A Close Look at the Galactic Ecosystem: the Canadian Galactic Plane Survey
Authors: Kothes Roland , Landecker Tom L. 
Published: October 2010

AbstractEnergy and mass interchanges in the interstellar medium are driven by the life-cycle of stars. They appear in our own Galaxy over a broad range of scales, from point-like injection from stars to global input on the scale of spiral density waves. Understanding this Galactic Ecosystem requires observations of the different phases of the ISM over this large angular dynamic range. The Canadian Galactic Plane Survey (CGPS) is a project to combine radio, millimeter, and infrared surveys of the Galactic plane, providing arcminute-scale images of all major components of the interstellar medium over a large portion of the Galactic disk.
Galactic AGB stars from the IPHAS survey
Authors: Wright N. J. , Barlow M. J. , Greimel R. , Drew J. E. , Matsuura M. 
Published: October 2010

AbstractWe present a photometric analysis of the properties of asymptotic giant branch stars identified in the INT Photometric H-alpha Survey (IPHAS) of the northern Galactic plane. Follow-up spectroscopy has revealed that the IPHAS (r - Ha) colour is a valuable diagnostic of the photospheric C/O ratio, and may be used to identify hundreds of carbon and S-type stars.
Mapping the Milky Way with LSST
Authors: Ivezić Željko 
Published: October 2010

AbstractThe Large Synoptic Survey Telescope (LSST) is the most ambitious ground-based survey currently planned in the visible band. Mapping of the Milky Way is one of the four main science and design drivers. The main 20,000 sq.deg. large survey area will be imaged about 1000 times in six bands (ugrizy) during the anticipated 10 years of operations, with the first light expected in 2015. These data will result in databases including 10 billion galaxies and a similar number of stars, and will serve the majority of science programs. In the Milky Way context, these deep LSST data will enable unprecedented studies of distant stars in Galactic halo, as well as intrinsically faint nearby objects, such as white dwarfs and LTY dwarfs.