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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731895.0, MPI für Astronomie / Publikationen_mpia
Calibration of evolutionary diagnostics in high-mass star formation
Authors:Molinari, S.; Merello, M.; Elia, D.; Cesaroni, R.; Testi, L.; Robitaille, T.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:The Astrophysical Journal Letters
Issue / Number:1
Start Page:id. L8 (8 pp)
Audience:Not Specified
Abstract / Description: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 ≥slant {10}5 cm‑3, toward 51 dense clumps with M≥slant 1000 M {}ȯ and uniformly spanning ‑2 ≲ Log(L/M) [L {}ȯ /M {}ȯ ] ≲ 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 ≤slant 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.
Free Keywords:ISM: clouds; ISM: molecules; stars: formation; stars: protostars
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.3847/2041-8205/826/1/L8
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