86-GHz SiO masers in Galactic centre OH/IR stars
Abstract
We present results on a search for 86.243-GHz SiO (J = 2→1, $v$ = 1) maser emission toward 67 OH/IR stars located near the Galactic centre. We detected 32 spectral peaks, of which 28 correspond to SiO maser lines arising from the envelopes of these OH/IR stars. In OH/IR stars, we obtained an SiO maser detection rate of about $40\%$ . We serendipitously detected two other lines from OH/IR stars at ≈86.18 GHz, which could be due to a CCS-molecule transition at 86.181 GHz or probably to an highly excited OH molecular transition at 86.178 GHz. The detection rate of 86-GHz maser emission is found to be about $60\%$ for sources with the Midcourse Space Experiment (MSX) A - E < 2.5 mag; but it drops to $25\%$ for the reddest OH/IR stars with MSX A - E > 2.5 mag. This supports the hypothesis by Messineo (2002, A&A, 393, 115) that the SiO masers are primarily found in relatively thinner circumstellar material.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- August 2020
- DOI:
- 10.1093/pasj/psaa040
- arXiv:
- arXiv:2007.03398
- Bibcode:
- 2020PASJ...72...63M
- Keywords:
-
- circumstellar matter;
- Galaxy: stellar content;
- infrared: stars;
- masers;
- stars: late-type;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 4 figures, 14 pages