Astron. Astrophys. Suppl. Ser. 147, 181-185
New detections of OH sources towards the 6.7 GHz methanol masers
M. Szymczak - A.J. Kus
Send offprint request: M. Szymczak
Torun Centre for Astronomy, Nicolaus Copernicus University,
ul. Gagarina 11, PL-87100 Torun, Poland
Received May 29; accepted September 14, 2000
A sample of 6.7 GHz methanol masers has been searched for OH maser
emission at 1665 and 1667 MHz using the 32 m Torun radio telescope.
Eight new OH sources were detected. They are generally weak at radio and
infrared wavelengths. In the northern hemisphere sample of 68 methanol
sources the OH maser emission is associated with 49 sources.
Generally OH masers do not arise in weak FIR sources.
The ratio of OH to CH3
OH maser flux densities increases for objects
with blue FIR colour and probably reflects evolutionary changes in the star-forming regions.
Key words: masers -- surveys -- stars: formation -- ISM: molecules -- radio
lines: ISM -- HII regions
Copyright The European Southern Observatory (ESO)