Emission-Line Stars in the Canis Major Star-Formation Region

Abstract Using the Schmidt telescope of the Kiso Observatory, we have surveyed Hα-emission stars in the Canis Major star-formation region and its adjacent reference area. In the area of about 58 square degrees a total of 179 Hα-emission stars have been found in the magnitude range between K=6 and 15 with a majority in the V = 11–14 range. A comparison with the previous surveys reveals that 67 stars are common with ours, while several tens stars have shown different appearances of Hα emission in our survey, suggesting the variability of the Hα-emission strength. Photographic photometry in the UBV system has been carried out for the detected stars. Based on the color properties and on the location relative to the CMa R1 association, the stars are provisionally classified into two main groups of early-type Hα-emission stars and of T Tauri candidates. It is found that the early-type Hα-emission stars are distributed rather uniformly over the survey area in contrast to the group of T Tauri candidates which show good coincidence with the CMa R1 association in the surface distribution.