SIO MASER SURVEY OF LATE-TYPE STARS .1. SIMULTANEOUS OBSERVATIONS OF 6 TRANSITIONS OF (SIO)-SI-28 AND (SIO)-SI-29

Simultaneous observations of the (SiO)-Si-28 nu = 0, 1, 2, and 3, J = 1-0 and (SiO)-Si-29 nu = 0 and 1, J = 1-0 transitions for 102 late-typ e stars were made with a sensitivity of about 2 Jy at the 3 a level us ing the 45 m telescope of Nobeyama Radio Observatory (NRO). SiO maser emission was detected in 83 stars; seven of them being new detections. The nu = 3 maser was detected in 12 stars with eight new detections. Most of the nu = 3 masers occur at the same radial velocity of the str ongest spikes of the nu = 1 and 2 masers. We also newly found the (SiO )-Si-29 nu = 0 maser in six stars. The (SiO)-Si-29 nu = 0 line is stro nger and narrower than the (SiO)-Si-29 nu = 0 line, indicating that th e (SiO)-Si-29 line is masing. In most cases, the (SiO)-Si-29 line show s a single narrow profile (FWHM=1 to 3 km s(-1)), with peak radial vel ocities coincident with the stellar velocity derived from OH maser and /or SiO/CO thermal lines within 1 km s(-1). Therefore, this maser line provides excellent means to measure the stellar velocities of late-ty pe stars. The (SiO)-Si-29 nu = 0, J = 1-0 Line was detected in eleven stars, with three new detections.