Date of Award
Summer 8-21-2022
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Physics
First Advisor
Anuj Sarma, PhD
Second Advisor
Bernhard Beck-Winchatz, PhD
Third Advisor
Jesus Pando, PhD
Abstract
Class I and Class II methanol (CH3OH) masers are believed to be good indicators for regions where high mass stars are being formed. High mass stars are important because they inuence the evolution of the Galaxy, but many details of their formation remain unknown. I present an investigation into the association of Class I and Class II CH3OH masers with high mass star formation in our Galaxy, in particular the evolutionary stages at which they occur. To do so, I have compared data on high mass star forming regions from the ATLASGAL survey with catalogs of Class I and Class II CH3OH maser observations collected by the MaserDB project. Of the 542 Class I CH3OH masers at 44 and 95 GHz listed in the MaserDB catalog that are within the range of the ATLASGAL survey, I _nd that 534 are associated with an ATLASGAL source. This means that 44 and 95 GHz Class I CH3OH masers are excellent tracers of high mass star forming regions. Of the 1145 Class II CH3OH masers at 6.7 GHz listed in the MaserDB catalog that are within the range of the ATLASGAL survey, 789 are associated with an ATLASGAL source. I also determined that 328 Class I CH3OH maser sources are associated with Class II CH3OH masers. Association of CH3OH masers with four evolutionary stages of ATLASGAL sources was also examined. These four stages, in order from earliest to latest, are quiescent, protostellar, Young Stellar Object (YSO), and H II region. I found that 2.1% of Class I CH3OH masers were associated with ATLASGAL sources in the quiescent stage, but only 0.5% of Class II CH3OH masers were associated with ATLASGAL sources in the quiescent stage. This is in line with current thinking that Class I CH3OH masers occur earlier in the star formation process. Association rates of both types of CH3OH masers with ATLASGAL sources in the protostellar and YSO stages were found to be similar (11% and 31%, respectively). The association rate with H II regions was 28.8% for Class I CH3OH masers, and 31.3% for Class II CH3OH masers. Although we have no formal errors to compute to verify whether these numbers are significant, they are in line with the general belief that Class I CH3OH maser emission begins early during the high mass star formation process and likely ends at an earlier period compared to Class II CH3OH masers. This thesis demonstrates that CH3OH masers are indeed excellent tracers of high mass star forming regions. Future work should focus on CH3OH maser surveys of ATLASGAL sources to see if there is an undiscovered population of CH3OH masers, and high angular resolution follow-ups.
Recommended Citation
Wilson, Nathanael, "HIGH MASS STAR FORMATION AND METHANOL MASERS" (2022). College of Science and Health Theses and Dissertations. 509.
https://via.library.depaul.edu/csh_etd/509
SLP Collection
no