Astrophys. J., 669, L37-L40 (2007/November-1)
Signatures of inflow motion in cores of massive star formation: potential collapse candidates.
WU Y., HENKEL C., XUE R., GUAN X. and MILLER M.
Abstract (from CDS):
Using the IRAM 30 m telescope, a mapping survey in optically thick and thin lines was performed toward 46 high-mass-star-forming regions. The sample includes UC H II precursors and UC H II regions. Seventeen sources are found to show ``blue profiles'', the expected signature of collapsing cores. The excess of sources with blue over red profiles [(Nblue-Nred)/Ntotal] is 29% in the HCO+ J=1-0 line, with a probability of 0.6% that this is caused by random fluctuations. UC H II regions show a higher excess (58%) than UC H II precursors (17%), indicating that material is still accreted after the onset of the UC H II phase. Similar differences in the excess of blue profiles as a function of evolutionary state are not observed in low-mass-star-forming regions. Thus, if confirmed for high-mass-star-forming sites, this would point to a fundamental difference between low- and high-mass-star formation. Possible explanations are inadequate thermalization, stronger influence of outflows in massive early cores, larger gas reserves around massive stellar objects, or different trigger mechanisms between low- and high-mass-star formation.
ISM: Kinematics and Dynamics - ISM: Molecules - Radio Lines: ISM - Stars: Formation
Table 2: [WHX2007] HHMMm+DDMMWW N=7, [WHX2007] S86WW (No. S86SE).
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