Detections of SiO and H2O masers in the bipolar nebula IRAS 19312+1950

Abstract

We report on the detection of SiO and H2O masers toward a newly found bipolar nebula, IRAS 19312+1950. This object exhibits extreme red IRAS color [ log(F25/F12) = 0.5 and log(F60/F25) = 0.7 ] and a nebulosity having a size of about 30″ extended to the south-west in the 2MASS near-infrared image. Toward this object, we have detected emission from the H2O 6(1,6)-5(2,3) transition, the SiO J = 1-0, v = 1 and 2, and J = 2-1, v = 1 transitions, and the SO 2(2)-1(1) and H13CN J = 1-0 transitions. The thermal lines of SO and H13CN are shifted by about 12 km s-1 in radial velocity with respect to the maser lines, indicating that thermal emission comes from the background molecular cloud. However, the SiO J - 2-1, v = 2 spectrum shows another component of SiO emission separated by 26 km s-1 from the main component, that might be formed in a rotating or expanding shell.