Letter to the Editor

Ring shaped 6.7 GHz methanol maser emission around a young high-mass star

¹ Toruń Centre for Astronomy, Nicolaus Copernicus University, Gagarina 11, 87-100 Toruń, Poland e-mail: annan@astro.uni.torun.pl
² Joint Institute for VLBI in Europe, Postbus 2, 7990 AA Dwingeloo, The Netherlands
³ Sterrewacht Leiden, Postbus 9513, 2300 RA Leiden, The Netherlands

Received: 3 August 2005
Accepted: 14 September 2005

Abstract

We report on EVN imaging of the 6.7 GHz methanol maser emission from the candidate high-mass protostar G23.657-0.127. The masers originate in a nearly circular ring of 127 mas radius and 12 mas width. The ring structure points at a central exciting object which characteristics are typical for a young massive star; its bolometric luminosity is estimated to be ≤ and ≤ for near (5.1 kpc) and far (10.5 kpc) kinematic distances, respectively. However, the spatial geometry of the underlying maser region remains ambiguous. We consider scenarios in which the methanol masers originate in a spherical bubble or in a rotating disc seen nearly face-on.