Starless clumps and the influence of near-by high-mass star formation Jochen Tackenberg MPIA, Heidelberg, Germany
To put constraints on the initial conditions early evolution of high-mass stars we extract a sample of starless clumps, and study the gas interaction in a region containing different evolutionary stages. To obtain a statistical significant sample of starless clumps we searched 20sq.deg of the 870micron ATLASGAL survey for dense dust and gas condensations. As the accretion luminosity reaches several hundred solar masses very only on, we excluded all clumps that have either GLIMPSE YSOs or 24 micron MIPSGAL point sources. Different from earlier studies we overcome the difficulties of point source extraction in the diffuse 24 micron background by visually inspecting all clumps, significantly improving the sensitivity and completeness. Finally, we find 210 starless clumps, 14 of them with masses above 1000 M_sun. We estimate the lifetime of these objects to be ~60kyr. (Tackenberg et al, 2012) >From this catalog we selected a region which contains different evolutionary stages, from HMPOs, to clouds that are infrared dark up to 160 micron. The region is on the edge of a wind blown bubble filled with low density ionized hydrogen. Between the ionizing source and the IR-dark starless clump, we trace the conversion of hydrogen from ionized over atomic to molecular gas. Nevertheless, we find no indications for a pile up of gas around the ionizing source.
Collaborators: H. Beuther Th. Henning, MPIA, Germany R. Plume, UoC, Canada F. Schuller, MPIfR, Germany