Near infrared photometry of stellar maser sources

Abstract

Results of infrared photometry in J, H, and K bands for 24 stellar maser sources are given. On the colour-colour diagram, nearly all the Mira variable masers are closer to the black body line than the normal M giants, which also have brighter H magnitudes. The main reason for the location of the Mira masers is the strong H 2O absorption bands at 1.4 and 1.9 μm. The dust envelopes for maser sources have temperature of 600 – 700 K, so the radiation shorter than 3 μm may be expected to be close to black body. The physical conditions in M supergiants are such that a peak intensity near 1 – 6 μm (the H band) may be expected. Maser-associated Mira variables have longer periods and redder colours than normal Mira stars and M giants, suggesting greater amount of mass ejection from the central stars.