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Maser Hunting in the Galactic Plane
[Thesis]. Manchester, UK: The University of Manchester; 2010.
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Abstract
The process of massive star formation greatly influences its surroundings through their outflows,vast UV output and shocks from their supernova death. They form at great distances from theEarth, enshrouded by dust and gas and have relatively short lifetimes. Astrophysical maserswhich form in these environments may act as locators of the star forming regions. The aim of this thesisis to study massive star formation using masers to probe these regions. The three main masers used in this thesis are the Class I and Class II methanol masers and the 6035 MHz ex-OH maser.The methanol masers are divided into two groups, Class I and Class II, based on their distance from a central source. The Class I masers are separated 1-2 pc from a central source, the central source is thestar forming region. The Class II masers are associated close to a star forming source. They are often associated with a 6035 MHz ex-OH maser.The 6035 MHz ex-OH masers are less common than the 6668 MHz Class I methanol masers. They are often found at sites of the 6668 MHz Class I masers and 1665/7 MHz OH masers. This thesis presents two maser surveys, the Methanol Multibeam (MMB)survey and the Class I survey. The MMB survey is currently surveying the entire Galactic Plane for the 6668 MHz Class II methanol maser and the 6035 MHz ex-OH maser. Over 60\% of the survey in the Southern hemisphere is now complete using the Parkes telescope. Over 900 6668 MHz Class I methanol masers and 110 6035 MHz ex-OH masers have been detected, with all of these masers pinpoint the location of newly forming high mass stars. Follow up observations to determine the precise locations of the 6668 MHz methanol and 6035 MHz ex-OH masers are currently underway.The first ever unbiased Class I survey has observed 1 sq degree of the Galactic Plane for the 44 GHz Class I methanol masers using the Mopra telescope in Australia. The 44 GHz Class II methanol masers arehypothesised to be associated with the outflows of high mass stellar objects. The Class I survey has detected 25 44 GHz methanol masers, with 23 being new detections. A smaller survey for 36 GHz Class Imasers was also conducted using the Mopra telescope centered on the region with the highest population of 44 GHz Class I masers.