Redshifted methanol absorption tracing infall motions of 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 titleAstronomy & Astrophysics
Department/SchoolSchool of Natural Sciences
PublisherE D P Sciences
Place of publication7, Ave Du Hoggar, Parc D Activites Courtaboeuf, Bp 112, Les Ulis Cedexa, France, F-91944
Rights statement© W. J. Yang et al. 2022 Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.