SiO maser survey of AGB stars in the North Galactic Cap

Abstract

A SiO maser survey in the J = 1-0, v = 1 and 2 transitions has been made for IRAS sources in the North Galactic Cap (b > 30°) with the Nobeyama 45 m radio telescope. The sources were selected on the basis of their IRAS 12/25-μm and 25/60-μm flux ratios as likely oxygen-rich AGB candidates. SiO masers were detected from 24 out of the 97 selected sources, where 17 were new detections. The distances and heights above the Galactic plane are calculated. The Galactic distribution of detected and undetected stars indicates that metallicity is likely to govern the detection rate. The Galactocentric angular velocities of the subsampled stars are derived and their variation with the Galactic height is discussed.