The Physical Properties of the<i>Midcourse Space Experiment</i>Galactic Infrared‐dark Clouds

Carey, Sean; Clark, F. O.; Egan, M. P.; Price, S. D.; Shipman, R.; Kuchar, T. A.

doi:10.1086/306438

Cited by 265 publications

(313 citation statements)

References 29 publications

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“…These clouds can have various shapes, from compact cores to filamentary morphologies of 1−5 arcmin in size. As an example, our demonstration field contains the already well-investigated IRDC G19.30+0.07 (Carey et al 1998). In Fig.…”

Section: Nature Of the Sourcesmentioning

confidence: 99%

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

Schüller¹,

Menten²,

Contreras

et al. 2009

A&A

725

927

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Context. Thanks to its excellent 5100 m high site in Chajnantor, the Atacama Pathfinder Experiment (APEX) systematically explores the southern sky at submillimeter wavelengths, in both continuum and spectral line emission. Studying continuum emission from interstellar dust is essential to locating the highest density regions in the interstellar medium, and deriving their masses, column densities, density structures, and large-scale morphologies. In particular, the early stages of (massive) star formation remain poorly understood, mainly because only small samples of high-mass proto-stellar or young stellar objects have been studied in detail so far. Aims. Our goal is to produce a large-scale, systematic database of massive pre-and proto-stellar clumps in the Galaxy, to understand how and under what conditions star formation takes place. Only a systematic survey of the Galactic Plane can provide the statistical basis for unbiased studies. A well characterized sample of Galactic star-forming sites will deliver an evolutionary sequence and a mass function of high-mass, star-forming clumps. This systematic survey at submillimeter wavelengths also represents a preparatory work for Herschel and ALMA. Methods. The APEX telescope is ideally located to observe the inner Milky Way. The Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 μm, with a beam size of 19. 2. Taking advantage of its large field of view (11. 4) and excellent sensitivity, we started an unbiased survey of the entire Galactic Plane accessible to APEX, with a typical noise level of 50−70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). Results. As a first step, we covered ∼95 deg 2 of the Galactic Plane. These data reveal ∼6000 compact sources brighter than 0.25 Jy, or 63 sources per square degree, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or protoclusters. Other compact sources harbor hot cores, compact H ii regions, or young embedded clusters, thus tracing more evolved stages after massive stars have formed. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M . In this first introductory paper, we show preliminary results from these ongoing observations, and discuss the mid-and long-term perspectives of the survey.

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Section: Nature Of the Sourcesmentioning

confidence: 99%

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

Schüller¹,

Menten²,

Contreras

et al. 2009

A&A

725

927

View full text Add to dashboard Cite

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“…In contrast to n(H 2 ), we cannot directly measure the value of N (H 2 CO) from our data. Values for the H 2 CO abundance relative to H 2 are reported to be in the range of X (H 2 CO) ∼ 10 −9 −10 −12 , for n(H 2 ) ∼ 10 4−6 cm −3 (e.g., Wootten et al 1978;Mundy et al 1987;Carey et al 1998;van der Tak et al 2000), therefore calculations of an average N (H 2 CO) assuming an X (H 2 CO) value from the literature would introduce a high degree of uncertainty.…”

Section: Large Velocity Gradient Modelingmentioning

confidence: 99%

Fragmentation in the massive star-forming region IRAS 19410+2336

Rodón

Beuther

Schilke

2012

A&A

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Context. The core mass functions (CMFs) of low-mass star-forming regions are found to resemble the shape of the initial mass function (IMF). A similar result is observed for the dust clumps in high-mass star-forming regions, although on spatial scales of clusters that do not resolve the substructure that is found in these massive clumps. The region IRAS 19410+2336 is one exception, having been observed on spatial scales on the order of ∼2500 AU, which are sufficient to resolve the clump substructure into individual cores. Aims. We investigate the protostellar content of IRAS 19410+2336 at high spatial resolution at 1.4 mm, determining the temperature structure of the region and deriving its CMF. Methods. The massive star-forming region IRAS 19410+2336 was mapped with the PdBI (BCD configurations) at 1.4 mm and 3 mm in the continuum and several transitions of formaldehyde (H 2 CO) and methyl cyanide (CH 3 CN). The H 2 CO transitions were also observed with the IRAM 30 m Telescope. Results. We detect 26 continuum sources at 1.4 mm with a spatial resolution as low as ∼2200 AU, several of them with counterparts at near-and mid-infrared wavelengths, distributed in two (proto)clusters. With the PdBI CH 3 CN and PdBI/IRAM 30 m H 2 CO emission, we derive the temperature structure of the region, ranging from 35 K to 90 K. Using these temperatures, we calculate the core masses of the detected sources, ranging from ∼0.7 M to ∼8 M . These masses are strongly affected by the spatial filtering of the interferometer, which removes a common envelope with ∼90% of the single-dish flux. Considering only the detected dense cores and accounting for binning effects as well as cumulative distributions, we derive a CMF, with a power-law index β = −2.3 ± 0.2. We resolve the Jeans length of the (proto)clusters by one order of magnitude, and only find a small velocity dispersion between the different subsources. Conclusions. Since we cannot unambiguously differentiate between protostellar and prestellar cores, the derived CMF is not prestellar. Furthermore, because of the large fraction of missing flux, we cannot establish a firm link between the CMF and the IMF. This implies that future high-mass CMF studies will need to complement the interferometer continuum data with the short spacing information, a task suitable for ALMA. We note that the method of extracting temperatures using H 2 CO lines becomes less applicable when reaching the dense core scales of the interferometric observations because most of the H 2 CO appears to originate in the envelope structure.

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“…IRDCs were intially discovered by the ISO (Perault et al 1996) and MSX (Carey et al 1998;Egan et al 1998) surveys as regions of high contrast against the mid-infrared (MIR) background. The densest IRDCs may eventually form massive stars, Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.…”

Section: Introductionmentioning

confidence: 99%

The initial conditions of high-mass star formation: radiative transfer models of IRDCs seen in theHerschelHi-GAL survey

Wilcock

Kirk

Stamatellos

et al. 2011

A&A

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The densest infrared dark clouds (IRDCs) may represent the earliest observable stage of high-mass star formation. These clouds are very cold, hence they emit mainly at far-infrared and sub-mm wavelengths. For the first time, Herschel has provided multi-wavelength, spatially resolved observations of cores within IRDCs, which, when combined with radiative transfer modelling, can constrain their properties, such as mass, density profile and dust temperature. We use a 3D, multi-wavelength Monte Carlo radiative transfer code to model in detail the emission from six cores in three typical IRDCs seen in the Hi-GAL survey (G030.50+00.95, G031.03+00.26 and G031.03+00.76), and thereby to determine the properties of these cores and compare them with their low-mass equivalents. We found masses ranging from 90 to 290 M with temperatures from 8 to 11 K at the centre of each core and 18 to 28 K at the surface. The maximum luminosity of an embedded star within each core was calculated, and we rule out the possibility of significant high mass star formation having yet occurred in three of our cores.

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The Physical Properties of theMidcourse Space ExperimentGalactic Infrared‐dark Clouds

Cited by 265 publications

References 29 publications

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 $\mathsf{\mu}$m

Fragmentation in the massive star-forming region IRAS 19410+2336

The initial conditions of high-mass star formation: radiative transfer models of IRDCs seen in theHerschelHi-GAL survey

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