A global view on star formation: The GLOSTAR Galactic plane survey

V. 6.7 GHz methanol maser catalogue^★

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: hnguyen@mpifr-bonn.mpg.de
² CSIRO Space and Astronomy, PO Box 1130, Bentley, WA 6102, Australia
³ Centre for Astrophysics and Planetary Science, University of Kent, Ingram Building, Canterbury, Kent CT2 7NH, UK
⁴ IRAM, 300 rue de la piscine, 38406 Saint Martin d’Hères, France
⁵ Instituto de Astronomía, Universidad Nacional Autónoma de México (UNAM), Apdo Postal 70–264, Ciudad de México, Mexico
⁶ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
⁷ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
⁸ South African Radio Astronomy Observatory, 2 Fir St, Black River Park, Observatory 7925, South Africa
⁹ Department of Earth & Space Sciences, Indian Institute of Space Science and Technology, Trivandrum 695547, India

Received: 25 May 2022
Accepted: 17 July 2022

Abstract

Class II methanol (CH₃OH) masers are amongst the clearest signposts of recent high-mass star formation (HMSF). A complete catalogue outlines the distribution of star formation in the Galaxy, the number of young star-forming cores, and the physical conditions of their environment, made possible by the Global View on Star Formation (GLOSTAR) survey. This blind survey of the radio regime of 4–8 GHz maps the Galactic mid-plane in the radio continuum, 6.7 GHz methanol line, the 4.8 GHz formaldehyde line, and several radio recombination lines. We present an analysis of the observations of the 6.7 GHz CH₃OH maser transition using data from the D-configuration of the Very Large Array (VLA). We analysed data covering Galactic longitudes from –2° < l < 60° and Galactic latitudes of |b| < 1°. We detected a total of 554 methanol masers, out of which 84 are new, and we catalogued their positions, velocity components, and integrated fluxes. With a typical noise level of ~18 mJy beam⁻¹, this is the most sensitive unbiased methanol survey for methanol masers to date. We also searched for dust continuum and radio continuum associations, finding that 97% of the sources are associated with dust and 12% are associated with radio continuum emission.