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ATLASGAL - Kinematic distances and the dense gas mass distribution of the inner Galaxy | | M. Wienen
; F. Wyrowski
; K. M. Menten
; J. S. Urquhart
; T. Csengeri
; C. M. Walmsley
; S. Bontemps
; D. Russeil
; L. Bronfman
; B. S. Koribalski
; F. Schuller
; | | Date: |
27 Feb 2015 | | Abstract: | The formation of high mass stars and clusters occurs in giant molecular
clouds. Objects in evolved stages of massive star formation such as protostars,
hot molecular cores, and ultracompact HII regions have been studied in more
detail than earlier, colder objects. With this in mind, the APEX Telescope
Large Area Survey of the whole inner Galactic plane at 870 micron (ATLASGAL)
has been carried out to provide a global view of cold dust and star formation
at submillimetre wavelengths. To derive kinematic distances to a large sample
of ATLASGAL clumps we divided them into groups of sources, which are located
close together, mostly within a radius of 2 pc, and have velocities in a
similar range with a median velocity dispersion of ~ 1 km/s. Using NH3, N2H+
and CS velocities we calculate near and far kinematic distances to 296 groups
of ATLASGAL sources in the first quadrant and 393 groups in the fourth
quadrant. We analyse HI self-absorption and HI absorption to resolve the
kinematic distance ambiguity. We obtain a scale height of ~ 28+/-2 pc and
displacement below the Galactic midplane of ~ -7+/-1 pc. Within distances from
2 to 18 kpc ATLASGAL clumps have a broad range of gas masses with a median of
1050 solar masses and a wide distribution of radii with a median of 0.4 pc.
Their distribution in galactocentric radii is correlated with spiral arms.
Using a statistically significant ATLASGAL sample we derive a power-law
exponent of -2.2+/-0.1 of the clump mass function. This is consistent with the
slope derived for clusters and with that of the stellar initial mass function.
Examining the power-law index for different galactocentric distances and
various source samples shows that it is independent of environment and
evolutionary phase. Fitting the mass-size relationship by a power law gives a
slope of 1.76+/-0.01 for cold sources such as IRDCs and warm clumps associated
with HII regions. | | Source: | arXiv, 1503.0007 | | Services: | Forum | Review | PDF | Favorites | |
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