Detection of a new methanol maser line with ALMA

¹ Institute of Applied Physics of the Russian Academy of Sciences, 46 Uljanov str., 603950 Nizhny Novgorod, Russia
e-mail: zin@appl.sci-nnov.ru
² Institute of Astronomy and Astrophysics, Academia Sinica, PO Box 23-141, Taipei 10617, Taiwan, ROC
³ Ural Federal University, 19 Mira street, 620002 Ekaterinburg, Russia

Received: 9 August 2017
Accepted: 24 September 2017

Abstract

Aims. We investigated the structure and kinematics of the gaseous disk and outflows around the massive young stellar object S255 NIRS3 in the S255IR-SMA1 dense clump.

Methods. Observations of the S255IR region were carried out with ALMA at two epochs in the compact and extended configurations.

Results. We serendipitously detected a new, never predicted, bright maser line at about 349.1 GHz, which most probably represents the CH₃OH 14₁−14₀ A⁻⁺ transition. The emission covers most of the 6.7 GHz methanol maser emission area of almost 1′′ and shows a velocity gradient in the same sense as the disk rotation. No variability was found in the time interval of several months. The emission is classified as Class II maser and probably originates in a ring at a distance of several hundred AU from the central star.