Ammonia from cold high-mass clumps discovered in the inner Galactic disk by the ATLASGAL survey

By M. Wienen, F. Wyrowski, F. Schuller, K. Menten, C. Walmsley, L. Bronfman, Fr'ed'erique Motte. 2012

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The APEX Telescope Large Area Survey: The Galaxy (ATLASGAL) is an unbiased continuum survey of the inner Galactic disk at 870 \mu m. It covers +/- 60 deg in Galactic longitude and aims to find all massive clumps at various stages of high-mass star formation in the inner Galaxy, particularly the earliest evolutionary phases. We aim to determine properties such as the gas kinetic temperature and dynamics of new massive cold clumps found by ATLASGAL. Most importantly, we derived their kinematical distances from the measured line velocities. We observed the ammonia (J,K) = (1,1) to (3,3) inversion transitions toward 862 clumps of a flux-limited sample of submm clumps detected by ATLASGAL and extracted 13CO (1-0) spectra from the Galactic Ring Survey (GRS). We determined distances for a subsample located at the tangential points (71 sources) and for 277 clumps whose near/far distance ambiguity is resolved. Most ATLASGAL clumps are cold with rotational temperatures from 10-30 K. They have a wide range of NH3 linewidths, which by far exceeds the thermal linewidth, as well as a broad distribution of high column densities with an NH3 abundance in the range of 5 to 30 * 10^{-8}. We found an enhancement of clumps at Galactocentric radii of 4.5 and 6 kpc. The high detection rate (87%) confirms ammonia as an excellent probe of the molecular content of the massive, cold clumps revealed by ATLASGAL. A clear trend of increasing rotational temperatures and linewidths with evolutionary stage is seen for source samples ranging from 24 \mu m dark clumps to clumps with embedded HII regions. The survey provides the largest ammonia sample of high-mass star forming clumps and thus presents an important repository for the characterization of statistical properties of the clumps and the selection of subsamples for detailed, high-resolution follow-up studies.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/9d676cc2ee6cf6857944beb9675722429284e12f

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Citations in the corpus

Our astrochemical heritage (2012, background): “[458]) to check if environmental conditions affect the fractionation process.”
HERSCHEL SURVEY OF GALACTIC OH+, H2O+, AND H3O+: PROBING THE MOLECULAR HYDROGEN FRACTION AND COSMIC-RAY IONIZATION RATE (2014, background): “90−00.26) has a systemic velocity of about 37 km s−1 as measured from various emission lines (e.g. van der Tak et al. 2000; Wienen et al. 2012; San José-Garćıa et al. 2013).”
ATLASGAL - properties of a complete sample of Galactic clumps (2017, methodology): “…at larger distances given the typical clump FWHM size of 1′; see figure 11 of Contreras et al. 2013). high-column density molecular gas (N(H2) & 1022 cm−2) 2 This temperature is the average kinetic temperature determined from ammonia observations of quiescent clumps (i.e., Wienen et al. 2012).”
The RMS survey : Galactic distribution of massive star formation (2013, result): “We have complemented these targeted observations with other high-density transitions reported in the literature (e.g. Bronfman, Nyman & May 1996; Schlingman et al. 2011; Wienen et al. 2012).”
ATLASGAL — towards a complete sample of massive star forming clumps ⋆ (2014, methodology): “Our ability to make significant progress in this field has been dramatically enhanced in recent years with the completion of a large number of Galactic plane surveys that cover the whole wavelength range from the near-infrared to the radio [e.g. the UKIDSS GPS, Lucas et al. 2008; GLIMPSE, Benjamin e”
LOW VIRIAL PARAMETERS IN MOLECULAR CLOUDS: IMPLICATIONS FOR HIGH-MASS STAR FORMATION AND MAGNETIC FIELDS (2013, methodology): “Specifically, the HMSF samples from Pillai et al. (2011), Li et al. (2013), Tan et al. (2013), and Wienen et al. (2012) contain virial parameters much smaller than those in the non–HMSF samples by Lada et al. (2008) and Enoch et al. (2006).”
The ATLASGAL survey: a catalog of dust condensations in the Galactic plane (2013, methodology): “This is also a reasonable physical scale for compact structures assumingthat a large fraction of the sources lie at the typical distance of∼ 4 kpc (e.g. Wienen et al. 2012), while Peretto & Fuller (2010) finds that 95% of the IRDCs are at distances of< 6 kpc with the mean distance between 3-5 kpc.”