Characteristics of OH emission from infrared stars.
Abstract
The characteristics of OH emission sources associated with late M-type variable stars are discussed. A total of 456 IR stars and 18 other objects were surveyed and OH emission was detected from 25 IR stars. Including four OH sources discovered by other observers, there are 29 OH emission sources associated with IR stars. In addition there are 8 OH sources which have OH emission characteristics similar to the OH/IR stars but for which no IR star has yet been detected. Based on their OH, IR and visual properties, the OH/IR stars can be divided into three groups. The group of OH/IR stars (19 stars) with their OH emission strongest at 1612 MHz and concentrated in two narrow velocity ranges is discussed in this paper. These OH sources are associated with late M-type long-period Mira variables which have excess radiation from 5-10 , indicating perhaps a circumstellar dust shell. It is proposed that the OH maser is pumped by the IR radiation and that the OH clouds are expanding asymmetrically outward from the star. Key words: OH emission - ilifrared stars - M4ype stars - mira variables
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1972
- Bibcode:
- 1972A&A....17..385W