THE PARKES SURVEY OF METHANOL MASERS AT 44.07 GHZ

被引:81
作者
SLYSH, VI [1 ]
KALENSKII, SV [1 ]
VALTTS, IE [1 ]
OTRUPCEK, R [1 ]
机构
[1] CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA
关键词
MASERS; STARS; FORMATION; ISM; MOLECULES; RADIO LINES;
D O I
10.1093/mnras/268.2.464
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
A survey of the Class I methanol masers in the transition 7(0)-6(1) A+ at 44.07 GHz has been carried out with the Parkes radio telescope. About 250 positions were searched in the direction of Galactic H II regions, H2O masers and 6.7-GHz Class II methanol masers. 55 new methanol emission sources at 44 GHz were detected, amongst which is the second strongest in the sky, M8E, with a flux density of 520 Jy. Most of the newly found sources are associated with H2O, OH and 6.7-GHz methanol masers and presumably are located in the common regions of star formation. A strong anticorrelation between Class I and II methanol masers was discovered. The nature of the anticorrelation is such that strong Class I masers do not co-exist with strong Class II masers and, where Class I and II masers co-exist, they have different radial velocities. The anticorrelation may be a consequence of the pumping radiation field acting on the population inversion, which is different for the two classes of masers. We suggest that the definitions of Class I and II methanol masers should be based solely on their transitions, and not by relating them to a particular type of associated astronomical object, as was originally proposed by Batrla et al. and Menten.
引用
收藏
页码:464 / 474
页数:11
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