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@Article{Benjamin2003,
Title title = {{GLIMPSE. I. An SIRTF Legacy Project to Map the Inner Galaxy}},
Author author = {{Benjamin}, R.~A. and {Churchwell}, E. and {Babler}, B.~L. and {Bania}, T.~M. and {Clemens}, D.~P. and {Cohen}, M. and {Dickey}, J.~M. and {Indebetouw}, R. and {Jackson}, J.~M. and {Kobulnicky}, H.~A. and {Lazarian}, A. and {Marston}, A.~P. and {Mathis}, J.~S. and {Meade}, M.~R. and {Seager}, S. and {Stolovy}, S.~R. and {Watson}, C. and {Whitney}, B.~A. and {Wolff}, M.~J. and {Wolfire}, M.~G.},
Journal journal = {\pasp},
Year year = {2003},
Month month =
aug,
Pages {aug},
pages = {953-964},
Volume volume = {115},
Abstract abstract = {The Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE), a Space Infrared Telescope Facility (SIRTF) Legacy Science Program, will be a fully sampled, confusion-limited infrared survey of 2/3 of the inner Galactic disk with a pixel resolution of
~1.2" ~1.2 using the Infrared Array Camera at 3.6, 4.5, 5.8, and 8.0 μm. The survey will cover Galactic latitudes |b|<=1deg and longitudes |l|=10deg-65° (both sides of the Galactic center). The survey area contains the outer ends of the Galactic bar, the Galactic molecular ring, and the inner spiral arms. The GLIMPSE team will process these data to produce a point-source catalog, a point-source data archive, and a set of mosaicked images. We summarize our observing strategy, give details of our data products, and summarize some of the principal science questions that will be addressed using GLIMPSE data. Up-to-date documentation, survey progress, and information on complementary data sets are available on the GLIMPSE Web site.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2003PASP..115..953B},
Doi doi = {10.1086/376696},
Eprint eprint = {astro-ph/0306274},
Keywords keywords = {Galaxy: Stellar Content, Galaxy: Structure, infrared: general, infrared: stars, ISM: General, Surveys, Stars: General},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Beuther2002,
Title title = {{High-Mass Protostellar Candidates. II. Density Structure from Dust Continuum and CS Emission}},
Author author = {{Beuther}, H. and {Schilke}, P. and {Menten}, K.~M. and {Motte}, F. and {Sridharan}, T.~K. and {Wyrowski}, F.},
Journal journal = {\apj},
Year year = {2002},
Month month =
feb,
Pages {feb},
pages = {945-965},
Volume volume = {566},
Abstract abstract = {We present a detailed 1.2 mm continuum and CS spectral line study of a large sample of 69 massive star forming regions in very early stages of evolution, most of them prior to building up an ultracompact H II region. The continuum data show a zoo of different morphologies and give detailed information on the spatial distributions, masses, column densities, and average densities of the whole sample. Fitting the radial intensity profiles shows that three parameters are needed to describe the spatial distribution of the sources: constant emission from the center out to a few arcseconds radius followed by a first power-law intensity distribution, which steepens farther outside into a second power-law distribution. The inner flat region is possibly caused by fragmentation of the large-scale cores into smaller subsources, whereas the steeper outer power-law distributions indicate finite sizes of the cores. Separating the sources into subsamples suggests that in the earliest stages prior to the onset of massive star formation, the intensity radial distributions are rather flat, resembling the structure of intensity peaks in more quiescent molecular clouds. Then in the subsequent collapse and accretion phase the intensity distributions become centrally peaked, with steep power-law indices. In this evolutionary stage the sources show also the broadest C34S line width. During the following phase, when ultracompact H II regions evolve, the intensity power-law radial distributions flatten out again. This is probably caused by the ignited massive stars in the center which disrupt the surrounding cores. The mean inner power-law intensity index mi (I~r-mi) is 1.2, corresponding to density indices p (n~r-p) of 1.6. In total, the density distributions of our massive star formation sites seem to be not too different from their low-mass counterparts, but we show that setting tight constrains on the density indices is very difficult and subject to many possible errors. The local densities we derive from CS calculations are higher (up to 1 order of magnitude) than the mean densities we find via the millimeter continuum. Such inhomogeneous density distribution reflects most likely the ubiquitous phenomenon of clumping and fragmentation in molecular clouds. Line width-mass relations show a departure from virial equilibrium in the stages of strongly collapsing cores.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2002ApJ...566..945B},
Doi doi = {10.1086/338334},
Eprint eprint = {astro-ph/0110370},
Keywords keywords = {ISM: Clouds, ISM: Molecules, Radio Continuum: ISM, Radio Lines: ISM, Stars: Formation},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Churchwell2006,
Title title = {{The Bubbling Galactic Disk}},
Author author = {{Churchwell}, E. and {Povich}, M.~S. and {Allen}, D. and {Taylor}, M.~G. and {Meade}, M.~R. and {Babler}, B.~L. and {Indebetouw}, R. and {Watson}, C. and {Whitney}, B.~A. and {Wolfire}, M.~G. and {Bania}, T.~M. and {Benjamin}, R.~A. and {Clemens}, D.~P. and {Cohen}, M. and {Cyganowski}, C.~J. and {Jackson}, J.~M. and {Kobulnicky}, H.~A. and {Mathis}, J.~S. and {Mercer}, E.~P. and {Stolovy}, S.~R. and {Uzpen}, B. and {Watson}, D.~F. and {Wolff}, M.~J.},
Journal journal = {\apj},
Year year = {2006},
Month month =
oct,
Pages {oct},
pages = {759-778},
Volume volume = {649},
Abstract abstract = {A visual examination of the images from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) has revealed 322 partial and closed rings that we propose represent partially or fully enclosed three-dimensional bubbles. We argue that the bubbles are primarily formed by hot young stars in massive star formation regions. We have found an average of about 1.5 bubbles per square degree. About 25% of the bubbles coincide with known radio H II regions, and about 13% enclose known star clusters. It appears that B4-B9 stars (too cool to produce detectable radio H II regions) probably produce about three-quarters of the bubbles in our sample, and the remainder are produced by young O-B3 stars that produce detectable radio H II regions. Some of the bubbles may be the outer edges of H II regions where PAH spectral features are excited and may not be dynamically formed by stellar winds. Only three of the bubbles are identified as known SNRs. No bubbles coincide with known planetary nebulae or W-R stars in the GLIMPSE survey area. The bubbles are small. The distribution of angular diameters peaks between 1' and 3' with over 98% having angular diameters less than 10' and 88% less than 4'. Almost 90% have shell thicknesses between 0.2 and 0.4 of their outer radii. Bubble shell thickness increases approximately linearly with shell radius. The eccentricities are rather large, peaking between 0.6 and 0.7; about 65% have eccentricities between 0.55 and 0.85.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2006ApJ...649..759C},
Doi doi = {10.1086/507015},
Keywords keywords = {ISM: H II Regions, ISM: Bubbles},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Churchwell2007,
Title title = {{The Bubbling Galactic Disk. II. The Inner 20{\deg}}},
Author author = {{Churchwell}, E. and {Watson}, D.~F. and {Povich}, M.~S. and {Taylor}, M.~G. and {Babler}, B.~L. and {Meade}, M.~R. and {Benjamin}, R.~A. and {Indebetouw}, R. and {Whitney}, B.~A.},
Journal journal = {\apj},
Year year = {2007},
Month month =
nov,
Pages {nov},
pages = {428-441},
Volume volume = {670},
Abstract abstract = {We report 269 mid-infrared bubbles within 10° of the Galactic center from visual inspection of the Spitzer GLIMPSE II Legacy Science program images. The surface density of bubbles is ~5 deg-2 or about 3 times that detected in longitudes |l|=10deg-65°, because the inner 10° of longitude were more thoroughly searched for small bubbles. There is a gradient in the number of bubbles with longitude with an increase of about a factor of 2 from 2° to 10° this is probably the result of several factors, including decreasing diffuse background brightness, confusion, and opacity with longitude. Bubble eccentricities are typically between 0.6 and 0.8, and >50% show evidence for blowouts, which we suggest result from local density fluctuations of the ISM and/or anisotropic stellar winds and radiation fields. The fraction of bubbles identified with H II regions and clusters is only about half that found at |l|>10deg. This is largely a result of the much smaller angular diameter of bubbles cataloged in the inner Galaxy than in the outer Galaxy. At least 12% of the bubbles have morphologies suggestive of triggered star formation. Most of the bubbles that show evidence for triggered star formation in the inner Galaxy have not formed secondary bubbles; it is postulated that this may be because they are too young to have had time for this to occur.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2007ApJ...670..428C},
Doi doi = {10.1086/521646},
Keywords keywords = {ISM: H II Regions, ISM: Bubbles, Stars: Formation},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Desert2008,
Title title = {{Submillimetre point sources from the Archeops experiment: very cold clumps in the Galactic plane}},
Author author = {{D{\'e}sert}, F.-X. and {Mac{\'{\i}}as-P{\'e}rez}, J.~F. and {Mayet}, F. and {Giardino}, G. and {Renault}, C. and {Aumont}, J. and {Beno{\^i}t}, A. and {Bernard}, J.-P. and {Ponthieu}, N. and {Tristram}, M.},
Journal journal = {\aap},
Year year = {2008},
Month month =
apr,
Pages {apr},
pages = {411-421},
Volume volume = {481},
Abstract abstract = {Aims: Archeops is a balloon-borne experiment, mainly designed to measure the Cosmic Microwave Background (CMB) temperature anisotropies at high angular resolution (~12 arcmin). By-products of the mission are shallow sensitivity maps over a large fraction of the sky (about 30%) in the millimetre and submillimetre range at 143, 217, 353 and 545 GHz. From these maps, we produce a catalog of bright submillimetre point sources. Methods: We present in this paper the processing and analysis of the Archeops point sources. Redundancy across detectors is the key factor allowing us to distinguish glitches from genuine point sources in the 20 independent maps. Results: We look at the properties of the most reliable point sources, totalling 304. Fluxes range from 1 to 10 000 Jy (at the frequencies covering 143 to 545 GHz). All sources are either planets (2) or of galactic origin. The longitude range is from 75 to 198 degrees. Some of the sources are associated with the well-known Lynds Nebulae and HII compact regions in the galactic plane. A large fraction of the sources have an IRAS counterpart. Except for Jupiter, Saturn, the Crab and Cas A, all sources show a dust-emission-like modified blackbody emission spectrum. Temperatures cover a range from 7 to 27 K. For the coldest sources (T < 10 K), a steep ν β emissivity law is found with a surprising β ~ 3 to 4. An inverse relationship between T and β is observed. The number density of sources at 353 GHz with flux brighter than 100 Jy is of the order of 1 per degree of Galactic longitude. These sources will provide a strong check for the calibration of the Planck HFI focal plane geometry as a complement to planets. These very cold sources observed by Archeops should be prime targets for mapping observations by the Akari and Herschel space missions and ground-based observatories. Tables 3 and 4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/481/411},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2008A%26A...481..411D},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1051/0004-6361:20078701},
Eprint eprint = {0801.4502},
Keywords keywords = {ISM: general, ISM: clouds, methods: data analysis, cosmology: observations, submillimeter, catalogs},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Deharveng2010,
Title title = {{A gallery of bubbles. The nature of the bubbles observed by Spitzer and what ATLASGAL tells us about the surrounding neutral material}},
Author author = {{Deharveng}, L. and {Schuller}, F. and {Anderson}, L.~D. and {Zavagno}, A. and {Wyrowski}, F. and {Menten}, K.~M. and {Bronfman}, L. and {Testi}, L. and {Walmsley}, C.~M. and {Wienen}, M.},
Journal journal = {\aap},
Year year = {2010},
Month month =
nov,
Pages {nov},
pages = {A6},
Volume volume = {523},
Abstract abstract = {Context. This study deals with infrared bubbles, the H ii regions they enclose, and triggered massive-star formation on their borders. Aims: We attempt to determine the nature of the bubbles observed by Spitzer in the Galactic plane, mainly to establish if possible their association with massive stars. We take advantage of the very simple morphology of these objects to search for star formation triggered by H ii regions, and to estimate the importance of this mode of star formation. Methods: We consider a sample of 102 bubbles detected by Spitzer-GLIMPSE, and catalogued by Churchwell et al. (2006; hereafter CH06). We use mid-infrared and radio-continuum public data (respectively the Spitzer-GLIMPSE and -MIPSGAL surveys and the MAGPIS and VGPS surveys) to discuss their nature. We use the ATLASGAL survey at 870 μm to search for dense neutral material collected on their borders. The 870 μm data traces the distribution of cold dust, thus of the dense neutral material where stars may form. Results: We find that 86% of the bubbles contain ionized gas detected by means of its radio-continuum emission at 20-cm. Thus, most of the bubbles observed at 8.0 μm enclose H ii regions ionized by O-B2 stars. This finding differs from the earlier CH06 results (~25% of the bubbles enclosing H ii regions). Ninety-eight percent of the bubbles exhibit 24 μm emission in their central regions. The ionized regions at the center of the 8.0 μm bubbles seem to be devoid of PAHs but contain hot dust. PAH emission at 8.0 μm is observed in the direction of the photodissociation regions surrounding the ionized gas. Among the 65 regions for which the angular resolution of the observations is high enough to resolve the spatial distribution of cold dust at 870 μm, we find that 40% are surrounded by cold dust, and that another 28% contain interacting condensations. The former are good candidates for the collect and collapse process, as they display an accumulation of dense material at their borders. The latter are good candidates for the compression of pre-existing condensations by the ionized gas. Thirteen bubbles exhibit associated ultracompact H ii regions in the direction of dust condensations adjacent to their ionization fronts. Another five show methanol masers in similar condensations. Conclusions: Our results suggest that more than a quarter of the bubbles may have triggered the formation of massive objects. Therefore, star formation triggered by H ii regions may be an important process, especially for massive-star formation. Appendices are only available in electronic form at http://www.aanda.org},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2010A%26A...523A...6D},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1051/0004-6361/201014422},
Eid eid = {A6},
Eprint eprint = {1008.0926},
Keywords keywords = {stars: formation, stars: early-type, ISM: bubbles, H ii regions},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Elmegreen1977,
Title title = {{Sequential formation of subgroups in OB associations}},
Author author = {{Elmegreen}, B.~G. and {Lada}, C.~J.},
Journal journal = {\apj},
Year year = {1977},
Month month =
jun,
Pages {jun},
pages = {725-741},
Volume volume = {214},
Abstract abstract = {It is noted that the Lyman continuum radiation from a cluster of OB stars will drive ionization (I) fronts into nearby neutral material and that an I front should be preceeded by a shock (S) front as it moves into an adjacent molecular cloud near dense nebulae. The gravitational stability of the high-density layer of neutral gas that accumulates between the I and S fronts is investigated to determine whether star formation is likely to occur there. The results show that the shocked neutral layer will become gravitationally unstable after several million years for I-S fronts propagating into molecular clouds of moderate density and that the stars which may form as the layer collapses are likely to be more massive than those which form in unshocked remote parts of the same molecular cloud. It is found that if the stars which eventually form in the shocked layer are OB stars, a new system of I-S fronts will propagate into the remaining cloud after these stars reach the main sequence, and another cycle of OB star formation will be initiated. It is therefore proposed that massive OB stars may be formed in sequential bursts during the lifetime of some large molecular clouds.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/1977ApJ...214..725E},
Doi doi = {10.1086/155302},
Keywords keywords = {B Stars, Lyman Spectra, Nebulae, O Stars, Star Clusters, Stellar Evolution, Interstellar Gas, Protostars, Shock Fronts, Stellar Models, Stellar Structure},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Miettinen2012,
Title title = {{A molecular line study of the filamentary infrared dark cloud G304.74+01.32}},
Author author = {{Miettinen}, O.},
Journal journal = {\aap},
Year year = {2012},
Month month =
apr,
Pages {apr},
pages = {A104},
Volume volume = {540},
Abstract abstract = {Context. Infrared dark clouds (IRDCs) are promising sites to study the earliest formation stages of stellar clusters and high-mass stars, and the physics of molecular-cloud formation and fragmentation. Aims: We attempt to improve our understanding of the physical and chemical properties of the filamentary IRDC G304.74+01.32 (hereafter, G304.74). In particular, we investigate the kinematical and dynamical state of the cloud and clumps within it, and the amount of CO depletion. Methods: All of the submillimetre peak positions in the cloud identified from our previous LABOCA 870-μm map were observed in C17O(2-1) with APEX. These are the first line observations along the whole filament that have been made so far. Selected positions were also observed in the 13CO(2-1), SiO(5-4), and CH3OH(5k - 4k) transitions at ~1 mm. Results: The C17O lines were detected towards all target positions at similar radial velocities. CO does not appear to be significantly depleted in the clumps, the largest depletion factors being only about 2. Two to three methanol 5k - 4k lines near ~241.8 GHz were detected towards all selected positions, whereas SiO(5-4) was seen in only one of these positions, namely SMM 3. In the band covering SiO(5-4), we also detected the DCN(3-2) line towards SMM 3. The 13CO(2-1) lines display blue asymmetric profiles, which are indicative of large-scale infall motions. The clumps show transonic to supersonic non-thermal motions, and a virial-parameter analysis suggests that most of them are gravitationally bound. The external pressure may also play a non-negligible role in the dynamics. Our analysis suggests that the fragmentation of the filament into clumps is caused by a
"sausage"-type sausage-type instability, in agreement with results from other IRDCs. Conclusions: The uniform C17O radial velocities along the G304.74 cloud shows that it is a coherent filamentary structure. Although the clumps appear to be gravitationally bound, the ambient turbulent ram pressure may be an important factor in the cloud dynamics. This is qualitatively consistent with our earlier suggestion that the filament was formed by converging supersonic turbulent flows. The poloidal magnetic field could resist the radial cloud collapse, which conforms to the low infall velocites that we derived. The cloud may be unable to form high-mass stars based on the mass-size threshold. The star-formation activity in the cloud, such as outflows, is likely responsible for the release of CO from the icy grain mantles back into the gas phase. Shocks related to outflows may also have injected CH3OH, SiO, and DCN into the gas-phase in SMM 3. This publication is based on data acquired with the Atacama Pathfinder EXperiment (APEX) under programmes 083.F-9302A and 087.F-9318A. APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2012A%26A...540A.104M},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1051/0004-6361/201118552},
Eid eid = {A104},
Eprint eprint = {1202.3051},
Keywords keywords = {ISM: abundances, ISM: molecules, ISM: clouds, stars: formation, ISM: individual objects: G304.74+01.32, radio lines: ISM},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Molinari2010,
Title title = {{Hi-GAL: The Herschel Infrared Galactic Plane Survey}},
Author author = {{Molinari}, S. and {Swinyard}, B. and {Bally}, J. and {Barlow}, M. and {Bernard}, J.-P. and {Martin}, P. and {Moore}, T. and {Noriega-Crespo}, A. and {Plume}, R. and {Testi}, L. and {Zavagno}, A. and {Abergel}, A. and {Ali}, B. and {Andr{\'e}}, P. and {Baluteau}, J.-P. and {Benedettini}, M. and {Bern{\'e}}, O. and {Billot}, N.~P. and {Blommaert}, J. and {Bontemps}, S. and {Boulanger}, F. and {Brand}, J. and {Brunt}, C. and {Burton}, M. and {Campeggio}, L. and {Carey}, S. and {Caselli}, P. and {Cesaroni}, R. and {Cernicharo}, J. and {Chakrabarti}, S. and {Chrysostomou}, A. and {Codella}, C. and {Cohen}, M. and {Compiegne}, M. and {Davis}, C.~J. and {de Bernardis}, P. and {de Gasperis}, G. and {Di Francesco}, J. and {di Giorgio}, A.~M. and {Elia}, D. and {Faustini}, F. and {Fischera}, J.~F. and {Fukui}, Y. and {Fuller}, G.~A. and {Ganga}, K. and {Garcia-Lario}, P. and {Giard}, M. and {Giardino}, G. and {Glenn}, J.~: and {Goldsmith}, P. and {Griffin}, M. and {Hoare}, M. and {Huang}, M. and {Jiang}, B. and {Joblin}, C. and {Joncas}, G. and {Juvela}, M. and {Kirk}, J. and {Lagache}, G. and {Li}, J.~Z. and {Lim}, T.~L. and {Lord}, S.~D. and {Lucas}, P.~W. and {Maiolo}, B. and {Marengo}, M. and {Marshall}, D. and {Masi}, S. and {Massi}, F. and {Matsuura}, M. and {Meny}, C. and {Minier}, V. and {Miville-Desch{\^e}nes}, M.-A. and {Montier}, L. and {Motte}, F. and {M{\"u}ller}, T.~G. and {Natoli}, P. and {Neves}, J. and {Olmi}, L. and {Paladini}, R. and {Paradis}, D. and {Pestalozzi}, M. and {Pezzuto}, S. and {Piacentini}, F. and {Pomar{\`e}s}, M. and {Popescu}, C.~C. and {Reach}, W.~T. and {Richer}, J. and {Ristorcelli}, I. and {Roy}, A. and {Royer}, P. and {Russeil}, D. and {Saraceno}, P. and {Sauvage}, M. and {Schilke}, P. and {Schneider-Bontemps}, N. and {Schuller}, F. and {Schultz}, B. and {Shepherd}, D.~S. and {Sibthorpe}, B. and {Smith}, H.~A. and {Smith}, M.~D. and {Spinoglio}, L. and {Stamatellos}, D. and {Strafella}, F. and {Stringfellow}, G. and {Sturm}, E. and {Taylor}, R. and {Thompson}, M.~A. and {Tuffs}, R.~J. and {Umana}, G. and {Valenziano}, L. and {Vavrek}, R. and {Viti}, S. and {Waelkens}, C. and {Ward-Thompson}, D. and {White}, G. and {Wyrowski}, F. and {Yorke}, H.~W. and {Zhang},
Q. },
Journal Q.},
journal = {\pasp},
Year year = {2010},
Month month =
mar,
Pages {mar},
pages = {314-325},
Volume volume = {122},
Abstract abstract = {Hi-GAL, the Herschel infrared Galactic Plane Survey, is an Open Time Key Project of the Herschel Space Observatory. It will make an unbiased photometric survey of the inner Galactic plane by mapping a wide strip in the longitude range in five wavebands between 70 μm and 500 μm. The aim of Hi-GAL is to detect the earliest phases of the formation of molecular clouds and high-mass stars and to use the optimum combination of Herschel wavelength coverage, sensitivity, mapping strategy, and speed to deliver a homogeneous census of star-forming regions and cold structures in the interstellar medium. The resulting representative samples will yield the variation of source temperature, luminosity, mass and age in a wide range of Galactic environments at all scales from massive YSOs in protoclusters to entire spiral arms, providing an evolutionary sequence for the formation of intermediate and high-mass stars. This information is essential to the formulation of a predictive global model of the role of environment and feedback in regulating the star-formation process. Such a model is vital to understanding star formation on galactic scales and in the early universe. Hi-GAL will also provide a science legacy for decades to come with incalculable potential for systematic and serendipitous science in a wide range of astronomical fields, enabling the optimum use of future major facilities such as JWST and ALMA.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2010PASP..122..314M},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1086/651314},
Eprint eprint = {1001.2106},
Keywords keywords = {ISM},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Morata2012,
Title title = {{Probing the physical and chemical structure of the CS core in LDN 673: multitransitional and continuum observations}},
Author author = {{Morata}, O. and {Girart}, J.~M. and {Estalella}, R. and {Garrod},
R.~T. },
Journal R.~T.},
journal = {\mnras},
Year year = {2012},
Month month =
sep,
Pages {sep},
pages = {1980-1991},
Volume volume = {425},
Abstract abstract = {High angular resolution observations of dense molecular cores show that these cores can be clumpier at smaller scales and that some of these clumps can also be unbound or transient. The use of chemical models of the evolution of the molecular gas provides a way to probe the physical properties of the clouds. We study the properties of the clump and interclump medium in the starless CS core in LDN 673 by carrying out a molecular line survey with the IRAM 30-m telescope towards two clumps and two interclump positions. We also observed the 1.2-mm continuum with the MAMBO-II bolometer at IRAM. The dust continuum map shows four condensations, three of them centrally peaked, coinciding with previously identified submillimetre sources. We confirm that the denser clump of the region, n ˜ 3.6 × 105 cm-3, is also the more chemically evolved, and it could still undergo further fragmentation. The interclump medium positions are denser than previously expected, likely n ˜ 1 × 103-1 × 104 cm-3 due to contamination, and are chemically young, similar to the gas in the lower density clump position. We argue that the density contrast between these positions and their general young chemical age would support the existence of transient clumps in the lower density material of the core. We were also able to find reasonable fits of the observationally derived chemical abundances to models of the chemistry of transient clumps.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2012MNRAS.425.1980M},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1111/j.1365-2966.2012.21521.x},
Eprint eprint = {1206.2837},
Keywords keywords = {stars: formation, ISM: abundances, ISM: clouds, ISM: individual objects: LDN 673, ISM: molecules, radio lines:
ISM },
Owner ISM},
owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Myers1996,
Title title = {{A Simple Model of Spectral-Line Profiles from Contracting Clouds}},
Author author = {{Myers}, P.~C. and {Mardones}, D. and {Tafalla}, M. and {Williams}, J.~P. and {Wilner}, D.~J.},
Journal journal = {\apjl},
Year year = {1996},
Month month =
jul,
Pages {jul},
pages = {L133},
Volume volume = {465},
__markedentry = {[cwatson:]},
Abstract abstract = {A simple analytic model of radiative transfer in two parts of a contracting cloud matches a wide range of line profiles in candidate infall regions and provides a sensitive estimate of Vin, the characteristic inward speed of the gas forming the line. The model assumes two uniform regions of equal temperature and velocity dispersion sigma , whose density and velocity are attenuation-weighted means over the front and rear halves of a centrally condensed, contracting cloud. The model predicts two-peak profiles for
"slow" slow infall, Vin << sigma , and red-shoulder profiles for
"fast" fast infall, Vin ~ sigma . A simple formula expresses Vin solely in terms of sigma and of observable parameters of a two-peak line. We apply the model to fit profiles of high and low optical depth lines observed in a dense core with no star (L1544, Vin = 0.006 km s-1), with an isolated protostar (L1527, 0.025 km s-1), and with a small group of stars (L1251B, 0.35 km s-1). The mass infall rate obtained from Vin and the map size varies from (2--40) x 10-6 Msolar yr-1 and agrees within a factor ~2 in each core with the independently determined rate ~ sigma 3 G-1 for a gravitationally collapsing isothermal sphere. This agreement suggests that the inward motions derived from the line profiles are gravitational in origin.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/1996ApJ...465L.133M},
Doi doi = {10.1086/310146},
Keywords keywords = {ISM: MOLECULES, LINE: PROFILES, STARS: FORMATION},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Pickett1998,
Title title = {{Submillimeter, millimeter and microwave spectral line catalog.}},
Author author = {{Pickett}, H.~M. and {Poynter}, R.~L. and {Cohen}, E.~A. and {Delitsky}, M.~L. and {Pearson}, J.~C. and {M{\"u}ller},
H.~S.~P. },
Journal H.~S.~P.},
journal = {\jqsrt},
Year year = {1998},
Month month =
nov,
Pages {nov},
pages = {883-890},
Volume volume = {60},
Abstract abstract = {This paper describes a computer-accessible catalog of submillimeter, millimeter, and microwave spectral lines in the frequency range between 0 and 10,000 GHz (i.e. wavelengths longer than 30 μm). The catalog can be used as a planning guide or as an aid in the identification and analysis of observed spectral lines in the interstellar medium, the Earth's atmosphere, and the atmospheres of other planets. The information listed for each spectral line includes the frequency and its estimated error, the intensity, the lower state energy, and the quantum number assignment. The catalog is continuously updated and at present has information on 331 atomic and molecular species and includes a total of 1,845,866 lines. The catalog has been constructed by using theoretical least-squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariance. Future versions of this catalog will add more atoms and molecules and update the present listings as new data appear. The catalog is available on-line via anonymous FTP at spec.jpl.nasa.gov and on the world wide web at http://spec.jpl.nasa.gov.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/1998JQSRT..60..883P},
Doi doi = {10.1016/S0022-4073(98)00091-0},
Keywords keywords = {Laboratory Spectra: Catalogues, Laboratory Spectra: MM Spectra, Laboratory Spectra: Sub-MM Spectra, Laboratory Spectra: Microwave Spectra, Atomic Spectra: Catalogues, Atomic Spectra: MM Spectra, Atomic Spectra: Sub-MM Spectra, Atomic Spectra: Microwave Spectra, Molecular Spectra: Catalogues, Molecular Spectra: MM Spectra, Molecular Spectra: Sub-MM Spectra, Molecular Spectra: Microwave Spectra},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Watson2009,
Title title = {{IR Dust Bubbles. II. Probing the Detailed Structure and Young Massive Stellar Populations of Galactic H II Regions}},
Author author = {{Watson}, C. and {Corn}, T. and {Churchwell}, E.~B. and {Babler}, B.~L. and {Povich}, M.~S. and {Meade}, M.~R. and {Whitney}, B.~A.},
Journal journal = {\apj},
Year year = {2009},
Month month =
mar,
Pages {mar},
pages = {546-555},
Volume volume = {694},
Abstract abstract = {We present an analysis of late-O/early-B-powered, parsec-sized bubbles and associated star formation using Two Micron All Sky Survey, GLIMPSE, MIPSGAL, and MAGPIS surveys. Three bubbles were selected from the Churchwell et al. catalog. We confirm that the structure identified in Watson et al. holds in less energetic bubbles, i.e., a photodissociated region, identified by 8 μm emission due to polycyclic aromatic hydrocarbons surrounding hot dust, identified by 24 μm emission and ionized gas, and identified by 20 cm continuum. We estimate the dynamical age of two bubbles by comparing bubble sizes to numerical models of Hosokawa and Inutsuka. We also identify and analyze candidate young stellar objects using spectral energy distribution (SED) fitting and identify sites of possible triggered star formation. Lastly, we identify likely ionizing sources for two sources based on SED fitting.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2009ApJ...694..546W},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1088/0004-637X/694/1/546},
Eprint eprint = {0901.1097},
Keywords keywords = {H II regions, infrared: stars, stars: formation},
Owner owner = {cwatson},
Primaryclass primaryclass = {astro-ph.GA},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Watson2010,
Title title = {{Triggered Star Formation and Dust Around Mid-infrared-identified Bubbles}},
Author author = {{Watson}, C. and {Hanspal}, U. and {Mengistu}, A.},
Journal journal = {\apj},
Year year = {2010},
Month month =
jun,
Pages {jun},
pages = {1478-1492},
Volume volume = {716},
Abstract abstract = {We use Two Micron All Sky Survey, GLIMPSE, and MIPSGAL survey data to analyze the young stellar object (YSO) and warm dust distribution around several mid-infrared-identified bubbles. We identify YSOs using J-band to 8 μm photometry and correlate their distribution relative to the photodissociation region (PDR; as traced by diffuse 8 μm emission), which we assume to be associated with and surrounding an H II region. We find that only 20% of the sample H II regions appear to have a significant number of YSOs associated with their PDRs, implying that triggered star formation mechanisms acting on the boundary of the expanding H II region do not dominate in this sample. We also measure the temperature of dust inside 20 H II regions using 24 μm and 70 μm MIPSGAL images. In eight circularly symmetric sources, we analyze the temperature distribution and find shallower temperature gradients than predicted by an analytic model. Possible explanations of this shallow temperature gradient are a radially dependent grain-size distribution and/or non-equilibrium radiative processes.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2010ApJ...716.1478W},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1088/0004-637X/716/2/1478},
Eprint eprint = {1006.0206},
Keywords keywords = {H II regions, ISM: bubbles, ISM: molecules, stars: formation, stars: massive},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Watson2008,
Title title = {{Infrared Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic H II Regions}},
Author author = {{Watson}, C. and {Povich}, M.~S. and {Churchwell}, E.~B. and {Babler}, B.~L. and {Chunev}, G. and {Hoare}, M. and {Indebetouw}, R. and {Meade}, M.~R. and {Robitaille}, T.~P. and {Whitney}, B.~A.},
Journal journal = {\apj},
Year year = {2008},
Month month =
jul,
Pages {jul},
pages = {1341-1355},
Volume volume = {681},
Abstract abstract = {We present an analysis of wind-blown, parsec-sized, mid-infrared bubbles and associated star formation using the GLIMPSE IRAC, MIPSGAL MIPS, and MAGPIS VLA surveys. Three bubbles from the Churchwell et al. catalog were selected. The relative distribution of the ionized gas (based on 20 cm emission), PAH emission (based on 8 μm, 5.8 μm, and lack of 4.5 μm emission), and hot dust (24 μm emission) is compared. At the center of each bubble there is a region containing ionized gas and hot dust surrounded by PAHs. We identify the likely source(s) of the stellar wind and ionizing flux producing each bubble based on SED fitting to numerical hot stellar photosphere models. Candidate YSOs are also identified using SED fitting, including several sites of possible triggered star formation.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2008ApJ...681.1341W},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1086/588005},
Eprint eprint = {0806.0609},
Keywords keywords = {ISM: H II Regions, Infrared: ISM, ISM: Bubbles, Radio Continuum: ISM, Stars: Formation},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Williams1999,
Title title = {{A Survey for Inward Motions in the Dense Gas around Young Stellar Clusters}},
Author author = {{Williams}, J.~P. and {Myers}, P.~C.},
Journal journal = {\apj},
Year year = {1999},
Month month =
jan,
Pages {jan},
pages = {208-217},
Volume volume = {511},
__markedentry = {[cwatson:6]},
Abstract abstract = {We report the results of a spectroscopic search for inward motions of the dense gas around 19 young stellar clusters. Single point observations of CS(2-1) and N2H+(1-0) were made using the Haystack 37 m telescope at
21" 21 resolution, and CS(2-1) and C34S(2-1) maps were made using the FCRAO 14 m telescope at
50" 50 resolution. Strong, spatially extended CS self-absorption is seen in Mon OB1-D, IRAS 20050+2720, and Cepheus A, which indicates that these sources are good candidates for follow-up observations of kinematic structure. In Cepheus A, in particular, we identify a region that shows inward motions over a region >~0.2 pc in extent, which suggests that models of core collapse should take into account the turbulent motions in these sources. We use the normalized velocity difference, δv=[v(thick)-v(thin)]/Δv(thin), between the optically thick (CS) and thin (N2H+ or C34S) lines to quantify the relative motions between the forward and central layers of dense gas. The average value of this velocity difference is not significantly different from zero for either data set, and there is no correlation with the source bolometric temperature as determined from IRAS flux measurements. Thus this cluster sample has no significant excess of sources with inward motions, unlike the samples of individual YSOs recently reported by Gregerson et al. and Mardones et al. The lower incidence of high absolute values of δv in our sample can be attributed to a lower optical depth in the CS line due to the greater distance, and therefore poorer linear resolution, of the sources here, and to the higher kinetic and excitation temperatures in these more massive, cluster forming environments.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/1999ApJ...511..208W},
Doi doi = {10.1086/306657},
Keywords keywords = {ISM: KINEMATICS AND DYNAMICS, ISM: MOLECULES, GALAXY: OPEN CLUSTERS AND ASSOCIATIONS: GENERAL, STARS: FORMATION, ISM: Kinematics and Dynamics, ISM: Molecules, Galaxy: Open Clusters and Associations: General, Stars: Formation},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Wolf-Chase1998,
Title title = {{The Protostellar Origin of a CS Outflow in S68N}},
Author author = {{Wolf-Chase}, G.~A. and {Barsony}, M. and {Wootten}, H.~A. and {Ward-Thompson}, D. and {Lowrance}, P.~J. and {Kastner}, J.~H. and {McMullin}, J.~P.},
Journal journal = {\apjl},
Year year = {1998},
Month month =
jul,
Pages {jul},
pages = {L193-L198},
Volume volume = {501},
Abstract abstract = {We have discovered a compact outflow of
~80" ~80 (0.12 pc) total extent toward S68N in the Serpens molecular cloud, which we have imaged in CS. We present outflow images acquired with the Haystack 37 m antenna and from combined Haystack and interferometric data, the latter at 12''×6'' angular resolution. The large derived outflow momentum flux (~2×10-4 Msolar km s-1 yr-1) is consistent with the high values found in the earliest protostellar stage (Bontemps et al.). We also present a new 450 μm continuum image of the S68N region at
7" 7 resolution obtained with the Submillimetre Common User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. We identify the source responsible for this outflow for the first time from the SCUBA image and report a new, more accurate position for S68N than has been used in previous investigations. We demonstrate spatial variability in the self-absorbed CS J=2-->1 line profile shapes at 0.03 pc
(18") (18) scales, emphasizing the need for detailed radiative transfer modeling for disentangling the complicated source kinematics.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/1998ApJ...501L.193W},
Doi doi = {10.1086/311469},
Keywords keywords = {ISM: CLOUDS, ISM: JETS AND OUTFLOWS, LINE: PROFILES, RADIO LINES: ISM, RADIO LINES: STARS, STARS: FORMATION, ISM: Clouds, ISM: Jets and Outflows, Line: Profiles, Radio Lines: ISM, Radio Lines: Stars, Stars: Formation},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@Article{Zinnecker2007,
Title title = {{Toward Understanding Massive Star Formation}},
Author author = {{Zinnecker}, H. and {Yorke}, H.~W.},
Journal journal = {\araa},
Year year = {2007},
Month month =
sep,
Pages {sep},
pages = {481-563},
Volume volume = {45},
Abstract abstract = {Although fundamental for astrophysics, the processes that produce massive stars are not well understood. Large distances, high extinction, and short timescales of critical evolutionary phases make observations of these processes challenging. Lacking good observational guidance, theoretical models have remained controversial. This review offers a basic description of the collapse of a massive molecular core and a critical discussion of the three competing concepts of massive star formation: monolithic collapse in isolated cores competitive accretion in a protocluster environment stellar collisions and mergers in very dense systems We also review the observed outflows, multiplicity, and clustering properties of massive stars, the upper initial mass function and the upper mass limit. We conclude that high-mass star formation is not merely a scaled-up version of low-mass star formation with higher accretion rates, but partly a mechanism of its own, primarily owing to the role of stellar mass and radiation pressure in controlling the dynamics.},
Adsnote adsnote = {Provided by the SAO/NASA Astrophysics Data System},
Adsurl adsurl = {http://adsabs.harvard.edu/abs/2007ARA%26A..45..481Z},
Archiveprefix archiveprefix = {arXiv},
Doi doi = {10.1146/annurev.astro.44.051905.092549},
Eprint eprint = {0707.1279},
Owner owner = {cwatson},
Timestamp timestamp =
{2015.09.09} {2015.09.09},
}
@ARTICLE{1994A&A...289..559L,
author = {{Lefloch}, B. and {Lazareff}, B.},
title =
"{Cometary {{Cometary globules. 1: Formation, evolution and
morphology}", morphology}},
journal = {\aap},
keywords = {Cometary Atmospheres, Evolution (Development), Globules, Hydrodynamics, Interstellar Matter, Morphology, Astronomical Models, Gravitation, H Ii Regions, Ionization, Ionizing Radiation, Simulation, Stability},
year =
1994, {1994},
month =
sep, {sep},
volume =
289, {289},
pages = {559-578},
adsurl = {http://adsabs.harvard.edu/abs/1994A%26A...289..559L},
adsnote = {Provided by the SAO/NASA Astrophysics Data
System} System},
}
@ARTICLE{1996A&AS..115...81B,
author = {{Bronfman}, L. and {Nyman}, L.-A. and {May}, J.},
title =
"{A {{A CS(2-1) survey of IRAS point sources with color characteristics of ultra-compact HII
regions.}", regions.}},
journal = {\aaps},
keywords = {GALAXY: STRUCTURE, INFRARED: INTERSTELLAR: CONTINUUM, INTERSTELLAR MEDIUM: CLOUDS, INTERSTELLAR MEDIUM: HII REGIONS, INTERSTELLAR MEDIUM: MOLECULES, RADIO LINES: MOLECULAR},
year =
1996, {1996},
month =
jan, {jan},
volume =
115, {115},
pages = {81},
adsurl = {http://adsabs.harvard.edu/abs/1996A%26AS..115...81B},
adsnote = {Provided by the SAO/NASA Astrophysics Data
System} System},
}
@ARTICLE{1997A&A...317L..55D,
author = {{Dutrey}, A. and {Guilloteau}, S. and {Guelin}, M.},
title =
"{Chemistry {{Chemistry of protosolar-like nebulae: The molecular content of the DM Tau and GG Tau
disks.}", disks.}},
journal = {\aap},
keywords = {STARS: T TAURI, BINARIES: CLOSE, CIRCUMSTELLAR MATTER, PRE-MAIN SEQUENCE, RADIO-LINES: STARS},
year =
1997, {1997},
month =
jan, {jan},
volume =
317, {317},
pages = {L55-L58},
adsurl = {http://adsabs.harvard.edu/abs/1997A%26A...317L..55D},
adsnote = {Provided by the SAO/NASA Astrophysics Data
System} System},
}
@ARTICLE{1997MNRAS.287..445C,
author = {{Chandler}, C.~J. and {Wood}, D.~O.~S.},
title =
"{VLA {{VLA observations of 43-GHz continuum and CS J=1-0 emission from Orion-IRc2 and the hot
core}", core}},
journal = {\mnras},
keywords = {ISM: ABUNDANCES, H II REGIONS, ISM: INDIVIDUAL: ORION-IRC2, ISM: MOLECULES, RADIO CONTINUUM: ISM, RADIO LINES: ISM},
year =
1997, {1997},
month =
may, {may},
volume =
287, {287},
pages = {445-454},
adsurl = {http://adsabs.harvard.edu/abs/1997MNRAS.287..445C},
adsnote = {Provided by the SAO/NASA Astrophysics Data
System} System},
}
@ARTICLE{1994ExA.....3...65K,
author = {{Kleinmann}, S.~G. and {Lysaght}, M.~G. and {Pughe}, W.~L. and {Schneider}, S.~E. and {Skrutskie}, M.~F. and {Weinberg}, M.~D. and {Price}, S.~D. and {Matthews}, K.~Y. and {Soifer}, B.~T. and {Huchra}, J.~P.},
title =
"{The {{The Two Micron All Sky
Survey}", Survey}},
journal = {Experimental Astronomy},
keywords = {Astronomical Catalogs, Astronomical Maps, Infrared Astronomy, Infrared Detectors, Infrared Sources (Astronomy), Infrared Spectroscopy, Infrared Stars, Infrared Telescopes, Near Infrared Radiation, Sky Surveys (Astronomy), Stellar Spectrophotometry, Astronomical Photography, Cameras, Galactic Radiation, Galactic Structure, Infrared Photography, Luminosity},
year =
1994, {1994},
month =
mar, {mar},
volume =
3, {3},
pages = {65-72},
doi = {10.1007/BF00430119},
adsurl = {http://adsabs.harvard.edu/abs/1994ExA.....3...65K},
adsnote = {Provided by the SAO/NASA Astrophysics Data
System} System},
}
@ARTICLE{1994A&A...291..943O,
author = {{Ossenkopf}, V. and {Henning}, T.},
title = {{Dust opacities for protostellar cores}},
journal = {\aap},
keywords = {Coagulation, Dust, Opacity, Protostars, Star Formation, Stellar Cores, Stellar Models, Absorptivity, Gas Density, Infrared Astronomy, Interstellar Extinction, Optical Properties, Radio Astronomy, Stellar Composition},
year = {1994},
month = {nov},
volume = {291},
pages = {943-959},
adsurl = {http://adsabs.harvard.edu/abs/1994A%26A...291..943O},
adsnote = {Provided by the SAO/NASA Astrophysics Data System},
}
