Publication Abstracts

Nyman et al. 1986

Nyman, L.-Å., L.E.B. Johansson, and R.S. Booth, 1986: SiO and H2O maser emission in OH/IR objects and late-type variable stars. Astron. Astrophys., 160, 352-366.

We have searched for 86 GHz SiO (ν = 1, J = 2-1) and H2O maser emission towards ∼20 unidentified OH/IR objects and ∼35 optically identified variable stars (mostly Mira variables) during a period of four years. Many of the sources were observed several times, giving some information on their temporal variations. 86 GHz SiO emission was clearly seen in only one OH/IR object, whereas eleven of the variable stars were detected, nine of them for the first time in this line. We have also searched for 43 GHz SiO (ν = 1 and 2, J = 1-0) emission towards eleven OH/IR objects and five sources were detected in both lines. The SiO maser emission behaves differently in OH/IR objects as compared with Mira variables; the 86 GHz SiO (ν = 1, J = 2- 1) photon flux is weak, the 43 GHz SiO (ν = 2, J = 1-0)/(ν = 1, J = 1-0) intensity ratio is larger than one, and the SiO emission is in general quite narrow (∼5kms- 1 ) and almost completely red or blueshifted with respect to the stellar radial velocity. An attempt to explain the appearance of strong masers in both vibrational states only in the 43 GHz transition is made by assuming an intrinsically weak pump mechanism which gives weak (ν = 1, J = 2- 1) emission. An increase in strength of the SiO (ν = 1, J = 0 to ν = 2, J = 1) infrared line by a line overlap, will very effectively invert the (J = 1-0) transitions and give strong emission only in the 43 GHz lines. H20 emission was detected in nine OH/IR objects, four of which are new detections. The H20 photon fluxes show a large spread, lying

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BibTeX Citation

  author={Nyman, L.-Å. and Johansson, L. E. B. and Booth, R. S.},
  title={SiO and H2O maser emission in OH/IR objects and late-type variable stars},
  journal={Astronomy and Astrophysics},

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RIS Citation

ID  - ny01000b
AU  - Nyman, L.-Å.
AU  - Johansson, L. E. B.
AU  - Booth, R. S.
PY  - 1986
TI  - SiO and H2O maser emission in OH/IR objects and late-type variable stars
JA  - Astron. Astrophys.
JO  - Astronomy and Astrophysics
VL  - 160
SP  - 352
EP  - 366
ER  -

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