SIMBAD references

2012A&A...544A.146W - Astronomy and Astrophysics, volume 544A, 146-146 (2012/8-1)

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


Abstract (from CDS):

The APEX Telescope Large Area Survey: the GALaxy (ATLASGAL) is an unbiased continuum survey of the inner Galactic disk at 870µm. It covers ±60° 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 10-30K with a median of 17K. They have a wide range of NH3 linewidths (1-7km/s) with 1.9km/s as median, which by far exceeds the thermal linewidth, as well as a broad distribution of high column densities from 1014 to 1016cm–2 (median of 2x1015cm–2) with an NH3 abundance in the range of 5 to 30x10–8. ATLASGAL sources are massive, >100M, and a fraction of clumps with a broad linewidth is in virial equilibrium. We found an enhancement of clumps at Galactocentric radii of 4.5 and 6kpc. The comparison of the NH3 lines as high-density probes with the GRS 13CO emission as low-density envelope tracer yields broader linewidths for 13CO than for NH3. The small differences in derived clump velocities between NH3 (representing dense core material) and 13CO (representing more diffuse molecular cloud gas) suggests that the cores are essentially at rest relative to the surrounding giant molecular cloud. 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 24µm 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.

Abstract Copyright:

Journal keyword(s): surveys - submillimeter: general - radio lines: ISM - ISM: molecules - ISM: kinematics and dynamics - stars: formation

VizieR on-line data: <Available at CDS (J/A+A/544/A146): table1.dat table2.dat table3.dat table4.dat table5.dat sp/*>

Nomenclature: Tables 1-5: [WWS2012] N=734.

CDS comments: Appendix A Calibrator G10.62 not found.

Simbad objects: 750

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