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

Abstract

The Australia Telescope Compact Array (ATCA) has been used to map class I methanol masers at 36 and 44GHz in G309.38-0.13. Maser spots are found at nine locations in an area of 50 × 30 arcsec2, with both transitions reliably detected at only two locations. The brightest spot is associated with shocked gas traced by 4.5-μm emission. The data allowed us to make a serendipitous discovery of a high-velocity 36-GHz spectral feature, which is blueshifted by about 30kms-1 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. © 2010 CSIRO. Journal compilation © 2010 RAS.