bluuebunny/crossref_metadata_2025 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

Studies 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

Ultra-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

We 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.
JD15 – Magnetic Fields in Diffuse Media
Authors: de Gouveia Dal Pino Elisabete M. , Lazarian Alex
Published: October 2010

Most of the baryonic matter in the Universe is permeated by magnetic fields which affect many, if not most, of astrophysical phenomena both, in compact sources and in diffuse gas.
Role of Magnetic Fields in Star Formation
Authors: Crutcher Richard M.
Published: October 2010

I 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

In 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.
SpS1-The Spitzer atlas of stellar spectra
Authors: Ardila David R. , Makowiecki W. , van Dyk S. , Song I. , Stauffer J. , Rho J. , Fajardo-Acosta S. , Hoard D. W. , Wachter S.
Published: October 2010

We present Spitzer Space Telescope spectra of 147 stars (R~64 - 128, λλ = 5 - 35 μm, S/N~100) covering most spectral and luminosity classes within the HR diagram. The spectra are available from the NASA/IPAC Infrared Science Archive (IRSA) and from the first author's webpage (http://web.ipac.caltech.edu/staff/ardila/Atlas/). The Atlas contains spectra of ‘typical’ stars, which may serve to refine galactic synthesis models, study stellar atmospheres, and establish a legacy for future IR missions, such as JWST.
SpS1-Dust and gas clearing in transitional disks
Authors: Brown Joanna M.
Published: October 2010

Understanding how disks dissipate is essential to studies of planet formation. Infrared observations of young stars demonstrate that optically-thick circumstellar disks disappear from around half the stars in low-mass star-forming regions by an age of 3 Myr and are almost entirely absent in 10 Myr old associations (e.g. Haisch et al., 2001). Accretion ceases on the same approximate timescale (e.g. Calvet et al. 2005). The disappearence of gas and dust - planetary building material - places stringent limits on the timescales of giant planet formation. During this crucial interval, planet(esimal)s form and the remaining disk material is accreted or dispersed. Mid-infrared spectrophotometry of protoplanetary disks has revealed a small sub-class of objects in the midst of losing their disk material. These disks have spectral energy distributions (SEDs) suggestive of large inner gaps with low dust content, often interpreted as a signature of young planets. Such objects are still rare although Spitzer surveys have significantly increased the number of known transitional objects (e.g. Brown et al. 2007, D'Alessio et al., 2005). However, spectrophotometric signatures are indirect and notoriously difficult to interpret as multiple physical scenarios can result in the same SED. Recent direct imaging from millimeter interferometry has confirmed the presence of large inner holes in transitional disks, providing additional constraints and lending confidence to current SED interpretations (Brown et al. 2008, Brown et al. 2009, Andrews et al. 2009, Isella et al., 2009).
SpS1-Spectroscopic observations of young disk evolution with Herschel and ALMA
Authors: Dent W. R. F.
Published: October 2010

In the next few years, both Herschel and ALMA will be providing unique new insights into the physics and chemistry of protoplanetary disks. In particular, they will be used to study how disks evolve from massive embedded systems around young Class 0 objects, through low-mass disks around optically-visible T Tauri stars, to debris disks around stars on the main-sequence. Gas dominates the mass in the younger systems, but in debris systems there is very little - if any. How does the gas disappear, what is the effect of this on planetary formation, and what is the role of “transition” disks? I outline some of the areas where these two large facilities will contribute to these studies, focussing on the Herschel Key project, GASPS, and looking forward to the role of ALMA.
AKARI near-infrared spectroscopy of brown dwarfs
Authors: Yamamura Issei , Tsuji Takashi , Tanabé Toshihiko , Nakajima Tadashi
Published: October 2010

Brown dwarfs (hereafter BDs) are of particular interest because of their extremely low-temperature atmospheres for comparison with atmospheres of giant planets. Aiming to obtain clues to understand the formation and disappearance of dust clouds and molecular abundances in BD photospheres, we conducted an observation programme of space-borne near-infrared spectroscopy of bright BDs with the Infrared Camera (IRC) on-board AKARI.
Spatially-resolved high-spectral resolution observations of the red supergiant Betelgeuse
Authors: Ohnaka K.
Published: October 2010

Red supergiants (RSGs) experience slow, intensive mass loss up to 10−4M⊙ yr−1. Despite its importance not only in stellar evolution but also in the chemical enrichment of the interstellar matter, the mass loss mechanism in RSGs is not well understood. A better understanding of the outer atmosphere of RSGs is a key to unraveling the mass-loss mechanism in these stars. High spatial resolution observations in IR molecular lines are very effective for probing the physical properties of the inhomogeneous outer atmosphere. We observed the prototypical RSG Betelgeuse (M1-2Ia–Ibe) in the CO first overtone lines with the spectro-interferometric instrument AMBER at the ESO's Very Large Telescope Interferometer (VLTI) using baselines of 16, 32, and 48 m. Details of the observations and the modeling are described in Ohnaka et al. (2009). The high-spectral (R = 4800–12000) and high-spatial resolution (9 mas) provided with AMBER allowed us to study inhomogeneities seen in the individual CO first overtone lines. Our AMBER observations represent the highest spatial resolution achieved for Betelgeuse, corresponding to five resolution elements over its stellar disk. The AMBER visibilities and closure phases in the K-band continuum can be reasonably fitted by a uniform disk with a diameter of 43.19 ± 0.03 mas or a limb-darkening disk with 43.56 ± 0.06 mas and a limb-darkening parameter of (1.2 ± 0.07) × 10−1. On the other hand, our AMBER data in the CO lines reveal salient inhomogeneous structures. The visibilities and phases (closure phases, as well as differential phases representing asymmetry in lines with respect to the continuum) measured within the CO lines show that the blue and red wings originate in spatially distinct regions over the stellar disk, indicating an inhomogeneous velocity field that makes the star appear different in the blue and red wings. Our AMBER data in the CO lines can be roughly explained by a simple model, in which a patch of CO gas is moving outward or inward with velocities of 10–15 km s−1, while the CO gas in the remaining region in the atmosphere is moving in the opposite direction at the same velocities. These velocities compare favorably with the macroturbulent velocities of 10–20 km s−1 derived by spectroscopic analyses. Also, the AMBER data are consistent with the presence of warm molecular layers (so-called MOLsphere) extending to ~1.4–1.5 R* with a CO column density of ~ 1 × 1020 cm−2. However, the present data are insufficient to constrain the surface pattern uniquely or to reconstruct an image. Our AMBER observations of Betelgeuse are the first spatially resolved study of the macroturbulence in a stellar atmosphere (photosphere and possibly MOLsphere as well) other than the Sun. The spatially resolved CO gas motion is likely to be related to convective motion in the upper atmosphere or intermittent mass ejections in clumps or arcs.
BICEP: a cosmic microwave background polarization telescope at the South Pole
Authors: Takahashi Yuki D.
Published: October 2010

Bicep 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

PLATO 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.
SpS5: ACCELERATING THE RATE OF ASTRONOMICAL DISCOVERY
Authors: Norris Ray P.
Published: October 2010

Special Session 5 on Accelerating the Rate of Astronomical Discovery addressed a range of potential limits to progress: paradigmatic, technological, organizational, and political. It examined each issue both from modern and historical perspectives, and drew lessons to guide future progress. A number of issues were identified which may regulate the flow of discoveries, such as the balance between large strongly-focussed projects and instruments, designed to answer the most fundamental questions confronting us, and the need to maintain a creative environment with room for unorthodox thinkers and bold, high risk, projects. Also important is the need to maintain historical and cultural perspectives, and the need to engage the minds of the most brilliant young people on the planet, regardless of their background, ethnicity, gender, or geography.
Photoabsorption of hydrocarbons in Titan's atmosphere
Authors: Magalhães Fabíola P. , de Souza Gerardo G. B. , Boechat-Roberty Heloisa M.
Published: October 2010

Titan, 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

We 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 dynamical architecture and habitable zones of the planetary system 55 Cancri
Authors: Ji Jianghui , Kinoshita Hiroshi , Liu Lin , Li Guangyu
Published: October 2010

We performed numerical simulations to study the secular orbital evolution and dynamical structure of the quintuplet planetary system 55 Cancri using the self-consistent orbital solutions of Fischer et al. (2008).
The detectability of habitable exomoons
Authors: Kipping David M. , Fossey Stephen J. , Campanella Giammarco
Published: October 2010

Despite 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.
Testing models for the formation of habitable planets
Authors: Miguel Yamila , Brunini Adrián
Published: October 2010

We report on a statistical study of models for the formation of habitable planets.
The Gaia astrometric survey
Authors: Sozzetti Alessandro
Published: October 2010

In 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

Jean 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.
Special Session 7 Young Stars, Brown Dwarfs, and Protoplanetary Disks
Authors: Gregorio-Hetem Jane , Alencar Silvia
Published: October 2010

In recent years our knowledge of star, brown dwarf and planet formation has progressed immensely due to new data in the IR domain (Spitzer telescope), new X-ray campaigns such as the Chandra Orion Ultradeep Project (COUP) and the X-ray Emission Survey of Taurus (XEST), with XMM-Newton, as well as adaptive optics results and synoptic studies of young stellar and substellar objects.
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

We 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

Unbiased, 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

I 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.
Young Stellar Object Variability at IRAC Wavelengths: Clues to Star and Planet Formation
Authors: Stauffer John R. , Morales Maria , Rebull Luisa
Published: October 2010

In Morales et al. (2009), we have recently investigated the mid-infrared (3.6 to 8.0 micron) variability of young-stellar objects (YSOs) using the IRAC camera on the Spitzer Space Telescope. Specifically, we obtained synoptic photometry of about 70 YSOs in the ~1 Myr old IC1396A globule over a 14 day period. More than half of the YSOs were detectably variable, with amplitudes up to about 0.2 magnitudes. About a third of these objects showed quasi-sinusoidal light curves with apparent periods of typically 5 to 12 days. At least two families of models can explain such light curves: (a) a Class II YSO with a photospheric hot spot which locally heats the inner circumstellar disk which is viewed from slightly above the disk plane, and (b) a YSO with a warped disk or with some other non-axisymmetric inner disk density profile, also seen with a view angle slightly above the disk plane. The two models can both yield light curve shapes and amplitudes similar to what we observe in the mid-infrared, but produce very different light curves at shorter wavelengths dominated by the stellar photosphere. Because we only had IRAC photometry for IC1396A, we were not able to discriminate between the two models for this set of data.
Gas Evolution in the Planet-Forming Region of Disks
Authors: Pascucci Ilaria
Published: October 2010

The 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

Jets 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.
Classical T Tauri-like Outflow Activity in the Brown Dwarf Mass Regime
Authors: Whelan E. T. , Ray T. P. , Bacciotti F. , Podio L. , Randich S.
Published: October 2010

Since 2005 we have been analysing the spectra of brown dwarfs (BDs) using the technique of spectro-astrometry and to date have found 5 outflows driven by BDs. Our aim is to obtain an understanding of outflow activity in the BD mass regime and make a comprehensive comparison with low mass protostars, in particular the classical T Tauri stars (CTTSs). Table 1 summarises some results for the sources in our sample. Also see Whelan et al. (2009b) for a complete discussion and comparison with CTTSs. Some noteworthy results include the asymmetry in the ISO-217 bipolar outflow which is revealed in the relative brightness of the two lobes (red-shifted lobe is brighter) and the factor of two difference in radial velocity (the red-shifted lobe is faster). Asymmetries are common in jets from low mass protostars (0.1 Msun to 2 Msun) and the observation of a strong asymmetry at such a low mass supports the idea that BD outflow activity is scaled down from CTTSs. In addition, Whelan et al. (2009a) find a strong contribution to the Hα line emitted by LS-RCrA 1 and evidence of a dust hole in its disk. Using methods previously applied to CTTS Whelan et al. (2009b) estimate the mass outflow rate (Ṁout) for LS-RCrA 1, ISO and ISO-Oph 102 Ṁout to be in the range 10−10 to 10−9 Msun yr−1 which is comparable to measured mass accretion rates.
Are pre-MS stars older than we thought?
Authors: Naylor Tim , Mayne N.J.
Published: October 2010

We 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.
Special Session 7 - Sumary and Concluding remarks
Authors: Alencar Silvia H. P. , Gregorio-Hetem Jane
Published: October 2010

This was a very pleasant and interesting meeting on star formation. The debate run on freely and contributions were of a very high level, including the oral contributions of four exceptional graduate students.
Preface - SpS8 - The Galactic Plane
Authors: Walton N. A. , Damineli A. , Hoare M. G. , Drew J. E.
Published: October 2010

The first digital astronomical surveys emphasised exploration of the sky away from the crowded Galactic Plane. But now, increased computing power has made it possible to take on comprehensive surveying of the Galactic Plane even at high spatial resolution and down to faint magnitude limits. A number of ambitious wide-area surveys sampling high energies, optical wavelengths, the infrared, sub-millimetre and radio ranges are complete, in process, or about to begin. The goals of these surveys are as broad as Galactic science itself, but are mainly focused either on solving key problems in star formation and stellar evolution, or on mapping the complex substructures of the Galactic bulge and disk in order to see more clearly how the whole is constructed. This meeting brought together researchers directly involved in the many surveys, along with specialists in the observations and modelling of the ISM, stellar evolution, and the structure of the Galactic Disk and Bulge.
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

A 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.
The Disk of Our Galaxy
Authors: Russeil Delphine
Published: October 2010

We review our knowledge about the spiral structure of the disk of our Galaxy using tracers of star formation. These tracers reveal a 4-arm picture of the Galaxy.
Deducing the Milky Way's Massive Cluster Population
Authors: Hanson M. M. , Popescu B. , Larsen S. S. , Ivanov V. D.
Published: October 2010

Recent 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

The 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

We 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

Energy 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

We 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

The 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.
A novel precision bender system for focusing mirrors
Authors: Trakhtenberg E. , Collins J. , Schmidt O.
Published: October 2010

A novel mirror bender system utilizing cam-shaft mover (CSM) with 100 µm eccentricity was designed and successfully tested. The system was initially tested and characterized in the laboratory, and then later the performance was verified using the Advanced Photon Source synchrotron radiation source. The force from the two separate CSMs is translated to both ends of a mirror through a small-diameter bellows feed-through. The system uses an internal spring assembly to compensate for atmospheric pressure. A compact gear box with 10:1 ratio between the stepper motor and cam shaft is used to increase the precision of the bender system. This bender system is equipped with a precise rotary potentiometer and load cell for feedback. A system resolution better than 0.2 µm per step was achieved. This bender system was designed as a separate unit, is very compact and can be used to bend a mirror in both the vertical and horizontal planes. Details of the system design, changes made from the prototype system to the production unit and test results are presented here.
Water and nutrient fluxes from major Mediterranean and Black Sea rivers: Past and future trends and their implications for the basin‐scale budgets
Authors: Ludwig W. , Bouwman A. F. , Dumont E. , Lespinas F.
Published: October 2010

The aim of this study is to produce future scenarios on the river inputs of water and nutrients (nitrate and phosphate) into the Mediterranean and Black Sea. They are based on the four contrasting scenarios that were developed by the Millenium Ecosystem Assessment (MEA) for the years 2030 and 2050 and implemented in a spatially explicit manner into the IMAGE model. We first identified the major drivers of the river fluxes by regression analyses, then tested the retained models against the past evolutions between 1970 and 2000, and finally applied the models to the MEA scenarios. For nutrients, the considered river data mainly refer to the large rivers for which long‐term time series exist (Rhone, Po, Ebro, and Danube). Here, recent trends were principally driven by fertilizer spreads (NO3, PO4), together with urban wastewater releases (PO4). Future trends remain in the envelope of the observed variability during the last 40 years, both for the large rivers and, when extrapolated to the basin scales, also for the entire Mediterranean and Black Sea. At regional scales, however, the budgets considerably change. In the northern parts of the Mediterranean drainage basin, they uniformly tend to decrease, but they may strongly increase in the south and east. Water discharge is examined on a basis of 37 rivers, showing that this parameter is clearly linked to the evolution of climate. Because of the ongoing evolution toward dryer and warmer conditions, we predict a significant trend of decreasing freshwater fluxes for the future, which already started in the past. Regional hot spots for this decrease are the drainage basin of the Alboran Sea and, when also considering the inhabitant specific water fluxes, the basins of the Aegean and north Levantine seas.
An analytical solution for tidal fluctuations in unconfined aquifers with a vertical beach
Authors: Yeh H. D. , Huang C. S. , Chang Y. C. , Jeng D. S.
Published: October 2010

The perturbation technique has been commonly used to develop analytical solutions for simulating the dynamic response of tidal fluctuations in unconfined aquifers. However, the solutions obtained from the perturbation method might result in poor accuracy for the case of the perturbation parameter being not small enough. In this paper, we develop a new analytical model for describing the water table fluctuations in unconfined aquifers, based on Laplace and Fourier transforms. In the new approach, the mean sea level is used as the initial condition and a free surface equation, neglecting the second‐order slope terms, as the upper boundary condition. Numerical results show that the present solution agrees well with the finite different model with the second‐order surface terms. Unlike Teo et al.'s (2003) approximation which restricts on the case of shallow aquifers, the present model can be applied to most of the tidal aquifers except for the very shallow one. In addition, a large‐time solution in terms of sine function is provided and examined graphically with four different tidal periods.
Winter 2010 in Europe: A cold extreme in a warming climate
Authors: Cattiaux J. , Vautard R. , Cassou C. , Yiou P. , Masson‐Delmotte V. , Codron F.
Published: October 2010

The winter of 2009/2010 was characterized by record persistence of the negative phase of the North‐Atlantic Oscillation (NAO) which caused several severe cold spells over Northern and Western Europe. This somehow unusual winter with respect to the most recent ones arose concurrently with public debate on climate change, during and after the Copenhagen climate negotiations. We show however that the cold European temperature anomaly of winter 2010 was (i) not extreme relative to winters of the past six decades, and (ii) warmer than expected from its record‐breaking seasonal circulation indices such as NAO or blocking frequency. Daily flow‐analogues of winter 2010, taken in past winters, were associated with much colder temperatures. The winter 2010 thus provides a consistent picture of a regional cold event mitigated by long‐term climate warming.
Homotopy formulas for the magnetic vector potential and magnetic helicity: The Parker spiral interplanetary magnetic field and magnetic flux ropes
Authors: Webb G. M. , Hu Q. , Dasgupta B. , Zank G. P.
Published: October 2010

Homotopy formulas are obtained for the magnetic vector potentialA, whereB= ∇ ×Ais the magnetic induction, which gives alternative methods for calculatingAfor a givenB, different from the Biot‐Savart formulas. The homotopy formulas are used to obtainAfor multipole potential fields and other potential fields, which are useful in relative helicity calculations. However, the formulas do not work for monopole and split monopole magnetic fields. In the latter case, there is no global continuous solution forA, but a global discontinuousAcan be constructed, which is continuous on two open sets that cover the sphere. The differential and integral forms of the helicity and relative helicity transport equations using both Eulerian and Lagrangian perspectives are discussed. The approach to magnetic helicity and magnetic helicity injection, based on a toroidal‐poloidal decomposition of the field, in which the field is represented by Euler potentials is also used in the analysis. The relative magnetic helicity and helicity injection rate for the Parker spiral interplanetary magnetic field, in which there is either a flat current sheet or a warped current sheet in the helioequatorial plane, are discussed. One of the homotopy formulas is used to provide an efficient way to calculate the relative helicity of interplanetary magnetic flux rope configurations observed by the WIND spacecraft.
Fitting a toroidal force‐free field to multispacecraft observations of a magnetic cloud
Authors: Nakagawa Tomoko , Matsuoka Ayako
Published: October 2010

A torus‐type flux rope model with an arbitrary aspect ratio was applied to an interplanetary magnetic cloud observed by ACE and Nozomi on 16–18 April 1999, when Nozomi was 0.2 AU downstream of ACE in the solar wind within 3° of heliocentric longitude. The large and small radii of the torus, the direction of the symmetric axis, and the crossing points of the spacecraft were determined so that they would minimize the sum of the square of the difference between the model field and the hourly averages of the observed field. Self‐similar expansion of the flux rope was assumed in proportion with the heliocentric distance. The best fit model had large and small radii of 0.16 and 0.09 AU, respectively. Both spacecraft passed through the northern part of the torus. Difference in the magnetic field observed by the two spacecraft was explained by the difference in their paths through the magnetic cloud. The model fit was consistent with the direction of the vector normal to the preceding planar magnetic structures. The chirality of the flux rope was positive (left handed), suggesting that the solar source was on the Northern Hemisphere. Assuming a probable association with the filament disappearance observed on 13 April 1999 at N16 E00, it is inferred that the filament had traveled in interplanetary space across the ecliptic plane. It was also found that nearly the same fitting result was obtained using a single‐spacecraft observation in the case of a torus‐shaped magnetic cloud with a small aspect ratio.
Modeling variations of summer upper tropospheric temperature and associated climate over the Asian Pacific region during the mid‐Holocene
Authors: Zhou Botao , Zhao Ping
Published: October 2010

The summer upper tropospheric temperature change and its association with atmospheric circulations and precipitation over the Asian Pacific region during the mid‐Holocene have been addressed by using outputs from a coupled ocean atmosphere general circulation model performed as part of the second phase of the Paleoclimate Modeling Intercomparison Project. The simulated result shows the summer oscillation pattern similar to the present Asian Pacific oscillation (APO) existed in the mid‐Holocene. When there was a warming (cooling) upper troposphere over East Asia, a cooling (warming) upper troposphere occurred over the midlatitudes of the North Pacific. Compared to the modern climate, however, the simulated mid‐Holocene temperature in the upper troposphere was higher over East Asia and lower over the midlatitudes of the North Pacific, indicating a stronger summer APO in the mid‐Holocene. Corresponding to such a condition, the North Pacific was modeled to be dominated by a high‐level cyclonic circulation difference and a low‐level anticyclonic circulation difference in the mid‐Holocene relative to the present, which favored the subsidence of airflows and thus resulted in less precipitation in this region. Meanwhile, East Asia was simulated to be occupied by an anticyclonic circulation difference in the upper troposphere and a cyclonic circulation difference in the lower troposphere. Accordingly, the ascending motion and the low‐level southerly wind strengthened in East Asia, leading to an increase of local precipitation in the mid‐Holocene. Therefore, the modeled mid‐Holocene climate suggests that the summer rainfall change over the Asian Pacific region may be a result of the strengthened APO in the upper troposphere.