SiOmaser
SiO masers are a type of astrophysical maser produced by silicon monoxide molecules in the inner regions of some stellar envelopes and, in some cases, in star-forming regions. They arise when a population inversion occurs in the rotational transitions of SiO within vibrationally excited states, leading to stimulated emission at microwave frequencies. The most prominent transitions are the v=1, J=1-0 line near 43 GHz and the v=2, J=1-0 line near 43 GHz, with higher transitions such as J=2-1 around 86 GHz observed in some sources.
SiO masers are most commonly found in oxygen-rich asymptotic giant branch (AGB) stars and red supergiants, where
Excitation of SiO masers is thought to involve a combination of radiative pumping by infrared radiation from
Applications of SiO masers include studying the dynamics and structure of the inner circumstellar environment, contributing