First Detection of 22 GHz H2O Masers in TX Camelopardalis

Abstract

Simultaneous time monitoring observations of H₂O 6 16 -5 23 , SiO J = 1-0, 2-1, 3-2, and 29 SiO v = 0, J = 1-0 lines are carried out in the direction of the Mira variable star TX Cam with the Korean VLBI Network single dish radio telescopes. For the first time, the H₂O maser emission from TX Cam is detected near the stellar velocity at five epochs from April 10, 2013 (o = 3.13) to June 4, 2014 (o = 3.89) including minimum optical phases. The intensities of H₂O masers are very weak compared to SiO masers. The variation of peak antenna temperature ratios among SiO v = 1, J = 1-0, J = 2-1, and J = 3-2 masers is investigated according to their phases. The shift of peak velocities of H₂O and SiO masers with respect to the stellar velocity is also investigated according to observed optical phases. The H₂O maser emission occurs around the stellar velocity during our monitoring interval. On the other hand, the peak velocities of SiO masers show a spread compared to the stellar velocity. The peak velocities of SiO J = 2-1, and J = 3-2 masers show a smaller spread with respect to the stellar velocity than those of SiO J = 1-0 masers. These simultaneous observations of multi-frequencies will provide a good constraint for maser pumping models and a good probe for investigating the stellar atmosphere and envelope according to their different excitation conditions.