SiO Masers

  • Moshe Elitzur
Part of the Astrophysics and Space Science Library book series (ASSL, volume 170)


The third astronomical maser species was discovered when Snyder and Buhl (1974) detected a group of new molecular emission features near 86 GHz in the Orion molecular cloud. The narrow linewidths and the compactness of the emission region suggested that this was a new maser, which Snyder and Buhl promptly identified as the J = 2 → 1 transition of the first vibrationally excited state (v = 1) of SiO. The almost immediate detection of two more rotational transitions, J = 1→ 0 and 3 → 2, in the same vibration state by Davis et al. (1974) and Thaddeus et al. (1974) confirmed this bold proposal. Subsequently, maser emission has been detected in rotational transitions in both v = 2 (Buhl et al. 1974) and v = 3 (Scalise and Lepine 1978). The rotational quantum numbers were also extended to higher values: J = 4 → 3 masers were discovered by Schwartz, Zuckerman and Bologna (1982); J = 5 → 4 by Clemens and Lane (1983); J = 6 → 5 by Jewell et al. (1987). SiO was the first molecule to present such a rich spectrum of maser lines. Figure 3.3 provides the energy level diagram, with detected maser transitions marked.


Optical Depth Column Density Maser Emission Pump Rate Vibration State 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer Science+Business Media Dordrecht 1992

Authors and Affiliations

  • Moshe Elitzur
    • 1
  1. 1.Department of Physics and AstronomyUniversity of KentuckyLexingtonUSA

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