High-velocity feature of the class I methanol maser in G309.38-0.13

TL;DR

This study used ATCA to map class I methanol masers in G309.38-0.13, discovering a high-velocity spectral feature indicating an outflow interacting with moving gas, a novel observation for such masers.

Contribution

First detection of a high-velocity spectral feature in class I methanol masers associated with a single molecular cloud.

Findings

High-velocity 36-GHz spectral feature found, blue-shifted by ~30 km/s.

Masers located in nine spots within a 50''x30'' area.

High velocity spread suggests outflow interacts with moving gas.

Abstract

The Australia Telescope Compact Array (ATCA) has been used to map class I methanol masers at 36 and 44 GHz in G309.38-0.13. Maser spots are found at nine locations in an area of 50''x30'', with both transitions reliably detected at only two locations. The brightest spot is associated with shocked gas traced by 4.5 micron emission. The data allowed us to make a serendipitous discovery of a high-velocity 36-GHz spectral feature, which is blue-shifted by about 30 km/s from the peak velocity at this frequency, but spatially located close to (within a few arcseconds of) the brightest maser spot. We interpret this as indicating an outflow parallel to the line of sight. Such a high velocity spread of maser features, which has not been previously reported in the class I methanol masers associated with a single molecular cloud, suggests that the outflow most likely interacts with a moving parcel of gas.