Redshifted methanol absorption tracing infall motions of high-mass star formation regions
Abstract
Context. Gravitational collapse is one of the most important processes in high-mass star formation. Compared with the classic blue-skewed profiles, redshifted absorption against continuum emission is a more reliable method to detect inward motions within high-mass star formation regions.
Aims: We aim to test if methanol transitions can be used to trace infall motions within high-mass star formation regions.
Methods: Using the Effelsberg-100 m, IRAM-30 m, and APEX-12 m telescopes, we carried out observations of 37 and 16 methanol transitions towards two well-known collapsing dense clumps, W31C (G10.6−0.4) and W3(OH), to search for redshifted absorption features or inverse P-Cygni profiles.
Results: Redshifted absorption is observed in 14 and 11 methanol transitions towards W31C and W3(OH), respectively. The infall velocities fitted from a simple two-layer model agree with previously reported values derived from other tracers, suggesting that redshifted methanol absorption is a reliable tracer of infall motions within high-mass star formation regions. Our observations indicate the presence of large-scale inward motions, and the mass infall rates are roughly estimated to be ≳10−3 M⊙ yr−1, which supports the global hierarchical collapse and clump-fed scenario.
Conclusions: With the aid of bright continuum sources and the overcooling of methanol transitions leading to enhanced absorption, redshifted methanol absorption can trace infall motions within high-mass star formation regions hosting bright H II regions.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- February 2022
- DOI:
- 10.1051/0004-6361/202142811
- arXiv:
- arXiv:2201.01792
- Bibcode:
- 2022A&A...658A.192Y
- Keywords:
-
- stars: formation;
- ISM: kinematics and dynamics;
- ISM: individual objects: W3(OH);
- ISM: individual objects: W31C(G10.6-0.4);
- ISM: molecules;
- radio lines: ISM;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 21 pages, 13 figures, 5 tables. Accepted for publication in A&