The Galactic Distribution of Infrared Dark Clouds

Jackson, James M.; Finn, Susanna C.; Rathborne, Jill; Chambers, E. T.; Simon, R.

doi:10.1086/587539

Cited by 90 publications

(119 citation statements)

References 25 publications

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“…The agreement between the distance estimates obtained with the association to IRDCs and the 2MASS extinction is also fairly good, with about a 20% systematic over-estimate of the extinction method compared to the kinetic method, and with a maximum associated discrepancy of 50%. This study is in agreement with the comparison performed by between the distance estimates of Marshall et al (2009), Simon et al (2006b) and Jackson et al (2008) on IRDCs. On the other hand no agreement is obtained between the SDSS extinction and the 2MASS extinction methods on the fraction of objects (144) for which we have both estimates.…”

Section: Combined Resultssupporting

confidence: 92%

“…Four different methods are required to cover all the sources: association with IRDCs; association with known molecular complexes; a three dimensional extinction method using the Two Micron All Sky Survey (2MASS Skrutskie et al 2006); and using Sloan Digital Sky Survey (SDSS, Abazajian et al 2003) data. Simon et al (2006b) and Jackson et al (2008) provide kinematic distance estimates for a total of 497 IRDCs extracted from the MSX catalogue (Simon et al 2006a) that consists of 10 931 objects. Kinematic distances are obtained via the observed radial velocity of gas tracers in the plane of the Galaxy.…”

Section: Distance Estimationmentioning

confidence: 99%

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Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

Ade¹,

Aghanim²,

Arnaud³

et al. 2011

A&A

154

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We present the statistical properties of the Cold Clump Catalogue of Planck Objects (C3PO), the first all-sky catalogue of cold objects, in terms of their spatial distribution, dust temperature, distance, mass, and morphology. We have combined Planck and IRAS data to extract 10 342 cold sources that stand out against a warmer environment. The sources are distributed over the whole sky, including in the Galactic plane, despite the confusion, and up to high latitudes (>30 • ). We find a strong spatial correlation of these sources with ancillary data tracing Galactic molecular structures and infrared dark clouds where the latter have been catalogued. These cold clumps are not isolated but clustered in groups. Dust temperature and emissivity spectral index values are derived from their spectral energy distributions using both Planck and IRAS data. The temperatures range from 7 K to 19 K, with a distribution peaking around 13 K. The data are inconsistent with a constant value of the associated spectral index β over the whole temperature range: β varies from 1.4 to 2.8, with a mean value around 2.1. Distances are obtained for approximately one third of the objects. Most of the detections lie within 2 kpc of the Sun, but more distant sources are also detected, out to 7 kpc. The mass estimates inferred from dust emission range from 0.4 M to 2.4 × 10 5 M . Their physical properties show that these cold sources trace a broad range of objects, from low-mass dense cores to giant molecular clouds, hence the "cold clump" terminology. This first statistical analysis of the C3PO reveals at least two colder populations of special interest with temperatures in the range 7 to 12 K: cores that mostly lie close to the Sun; and massive cold clumps located in the inner Galaxy. We also describe the statistics of the early cold core (ECC) sample that is a subset of the C3PO, containing only the 915 most reliable detections. The ECC is delivered as a part of the Planck Early Release Compact Source Catalogue (ERCSC).

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Section: Combined Resultssupporting

confidence: 92%

Section: Distance Estimationmentioning

confidence: 99%

Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

Ade¹,

Aghanim²,

Arnaud³

et al. 2011

A&A

154

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“…"Wat", "SW", "A" correspond to radio sources listed mainly in Watson et al (2003), Sewilo (2004) and . The molecular information is from Dame et al (1986) for "GMC", from Roman-Duval et al (2009) for "GRSMC" clouds, from Solomon et al (1987) for "Sol" clouds, from Jacq et al (1988) for "Bx" clouds and from Simon et al (2006) and Jackson et al (2008) for "IRDC". For "GMC" and "Bx" clouds the radius and velocity FWHM of the cloud is given in brackets.…”

Section: Appendix A: Figuresmentioning

confidence: 99%

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Russeil

Pestalozzi

Mottram

et al. 2011

A&A

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Context. Hi-GAL, an open time key-project of the Herschel satellite, was awarded 343 hours observing time to carry out a 5-band photometric imaging survey at 70, 160, 250, 350, and 500 μm of a |b| ≤ 1 • wide strip of the Milky Way Galactic plane in the longitude range −70 • ≤ l ≤ 70 • . Two 2 • × 2 • fields centred at l = 30 • and l = 59 • have been observed with the SPIRE and PACS photometric cameras in parallel mode during the Herschel science demonstration phase (SDP). From the images, compact sources are extracted for which the distance must be established in order to determine their physical properties. Aims. The aim of this paper is to present the distance determination strategy for the Hi-GAL compact sources. We illustrate this strategy for the two fields at l = 30 • and l = 59 • . Methods. The first step to determine the distance is to establish the LSR (local standard of rest) velocity of each compact source. The kinematic distance is then determined assuming a rotation curve for our Galaxy. To resolve the distance ambiguity for sources within the solar circle, we adopt a multiwavelength approach combining extinction maps, optical, and near infrared images, and velocity information from NH 3 , CO and HI data. When sources can be kinematically linked to optical H ii regions, the stellar distance of the exciting stars, when known, can be attributed to all linked sources. Results. In the two 2 • × 2 • SDP fields, 2678 compact sources have been identified and listed in the band-merged catalogue. About 93% of these sources have been assigned a radial velocity and distance. Conclusions. A multiwavelength approach is necessary to assign the correct velocity to sources (especially when CO spectra have a lot of features) and to determine the distance by solving the distance ambiguity. Also, several Hi-GAL sources seem to be in the interarm region. These sources have to be investigated with dedicated programme to be compared with sources located in the spiral arms.

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“…The choice of A v and the distance used by the SED fitter is an output from the fitting results, listed in Table 3 along with other parameters. We note that IRDCs in quadrant 4 are typically located at distances of ∼3 kpc (Jackson et al 2008), and distances over ∼8 kpc are unlikely because Spitzer-MIPS 24μm, IRAC 8μm and 3.6μm images are coded as red, green and blue respectively to compose the colour image which reveal the infrared dark filament/cloud. Yellow contours show the 870μm emission (starting at 0.1 Jy, in steps of 0.1 Jy) from the ATLASGAL data tracing the molecular clump associated with the infrared dark cloud.…”

Section: Sed Fittingmentioning

confidence: 99%

Highly Variable Young Massive Stars in Atlasgal Clumps

Kumar

Peña

Lucas

2016

ApJ

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High-amplitude variability in young stellar objects (YSOs) is usually associated with episodic accretion events. It has not been observed so far in massive YSOs. Here, the high-amplitude variable star sample of Contreras Peña et al. has been used to search for highly variable (ΔK 1 mag) sources coinciding with dense clumps mapped using the 850μm continuum emission by the ATLASGAL survey. A total of 18 variable sources are centered on the submillimeter clump peaks and coincide (<1″) with a 24μm point or compact (<10″) source. Of these 18 sources, 13 can be fit by YSO models. The 13 variable YSOs (VYSOs) have luminosities of ∼10 3 L e , an average mass of 8M e , and a range of ages up to 10 6 yr. A total of 11 of these 13 VYSOs are located in the midst of infrared dark clouds. Nine of the 13 sources have ΔK>2 mag, significantly higher compared to the mean variability of the entire VVV sample. The light curves of these objects sampled between 2010 and 2015 display rising, declining, or quasi-periodic behavior but no clear periodicity. Light-curve analysis using the Plavchan method shows that the most prominent phased signals have periods of a few hundred days. The nature and timescale of variations found in 6.7 Ghz methanol maser emission in massive stars are similar to that of the VYSO light curves. We argue that the origin of the observed variability is episodic accretion. We suggest that the timescale of a few hundred days may represent the frequency at which a spiraling disk feeds dense gas to the young massive star.

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The Galactic Distribution of Infrared Dark Clouds

Cited by 90 publications

References 25 publications

Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

Planckearly results. XXIII. The first all-sky survey of Galactic cold clumps

Giving physical significance to the Hi-GAL data: determining the distance of cold dusty cores in the Milky Way

Highly Variable Young Massive Stars in Atlasgal Clumps

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