%0 Generic
%A Tackenberg, Jochen
%D 2013
%F heidok:14904
%K Sternentstehung  massereiche Sterne  
%R 10.11588/heidok.00014904
%T Early stages of high-mass star formation
%U https://archiv.ub.uni-heidelberg.de/volltextserver/14904/
%X This thesis is dedicated to the formation of high-mass stars. In particular, we are interested  in the initial conditions that allow massive stars to form. Therefore, we first  examine the very initial stage of massive star formation.  Based on a statistical survey study over 20 deg2 from mid-infrared to sub-millimeter wavelengths,  we show that dense and massive starless clumps exist. Assuming that they will  form stellar clusters instead of single objects, we estimate their lifetime to be between  15 kyr and 60 kyr.  In order to understand such short lifetimes, we investigate the large-scale dynamical structure  of high-mass star-forming regions. Using N2H+ observations we find smooth largescale  velocity gradients in a number of filaments, which are consistent with gas flowing  along the filament. Analyzing HCO+ and H13CO+ spectra, we find global supersonic gas  infall onto a few regions.  To understand whether the dynamics of an expanding Hii region can trigger star formation,  we select a starless clump located on the rim of a bubble which is infrared-dark up  to 160 μm. In a multi-wavelengths approach we search for imprints of the bubble on the  gas. While an expanding Hii region might favor the formation of high-mass stars, we find  no evidence that it triggers the collapse.  In summary, this thesis emphasizes that high-mass star formation is a fast and dynamic  process.