Water Maser Survey toward Low‐Mass Young Stellar Objects in the Northern Sky with the Nobeyama 45 Meter Telescope and the Very Large Array

Abstract

We give a detailed presentation of all the data from a multiepoch 22 GHz H2O maser survey mainly toward low-mass young stellar objects (YSOs) using the Nobeyama 45 m telescope and the Very Large Array (VLA). Our major results are already published (our Paper I). The Nobeyama survey is the first complete H2O maser survey toward known Class 0 sources in the northern sky (δ > -35°) and is one of the most sensitive surveys ever performed. The survey was conducted from 1996 May through 1999 March over 32 periods. A total of 606 observations were carried out toward 173 YSOs, including 36 unknown luminosity sources, and toward 31 preprotostellar cores (PPSCs) in the Ophiuchus star-forming region. We detected 149 spectra toward 39 YSOs and zero spectra toward the 31 PPSCs. Subsequent to the Nobeyama survey, we performed a follow-up interferometric survey with the VLA in order to associate 19 maser sources detected by the 45 m telescope with individual YSOs. In this paper we compile properties of 142 YSOs together with their H2O maser activity. On the basis of this data set, we use properties of water maser emission as a probe of jet phenomena in low-mass stars.