2016ApJ...826L...8M -
Astrophys. J., 826, L8-L8 (2016/July-3)
Calibration of evolutionary diagnostics in high-mass star formation.
MOLINARI S., MERELLO M., ELIA D., CESARONI R., TESTI L. and ROBITAILLE T.
Abstract (from CDS):
The evolutionary classification of massive clumps that are candidate progenitors of high-mass young stars and clusters relies on a variety of independent diagnostics based on observables from the near-infrared to the radio. A promising evolutionary indicator for massive and dense cluster-progenitor clumps is the L/M ratio between the bolometric luminosity and the mass of the clumps. With the aim of providing a quantitative calibration for this indicator, we used SEPIA/APEX to obtain CH3C2H(J=12-11) observations, which is an excellent thermometer molecule probing densities 10^{5}/cm3, toward 51 dense clumps with M\geqslant 1000 M _☉ and uniformly spanning -2 <= Log(L/M) [L _☉/M _☉ ] <= 2.3. We identify three distinct ranges of L/M that can be associated to three distinct phases of star formation in massive clumps. For L/M \leqslant 1 no clump is detected in CH3C2H, suggesting an inner envelope temperature below ∼30K. For 1 <= L/M <= 10 we detect 58% of the clumps with a temperature between ∼30 and ∼35 K independently from the exact value of L/M; such clumps are building up luminosity due to the formation of stars, but no star is yet able to significantly heat the inner clump regions. For L/M >= 10 we detect all the clumps with a gas temperature rising with Log(L/M), marking the appearance of a qualitatively different heating source within the clumps; such values are found toward clumps with UCH ii counterparts, suggesting that the quantitative difference in T versus L/M behavior above L/M ∼ 10 is due to the first appearance of ZAMS stars in the clumps.
Abstract Copyright:
© 2016. The American Astronomical Society. All rights reserved.
Journal keyword(s):
ISM: clouds - ISM: molecules - stars: formation - stars: protostars
Nomenclature:
Table 1: [MME2016] NN (Nos 1-51).
Status at CDS
:
All or part of tables of objects could be ingested in SIMBAD with priority 2.
Simbad objects:
1
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