A Search for Galactic Carbon Stars

The carbon star is one of the best probes for the galactic study; (1) it is intrinsically bright (Mbol = − 2 to − 6) especially in the red and infrared wavelength regions, (2) it has spectral features readily detectable on objective prism plates due to their strong carbon molecular bands, (3) it is an evolved star distributed abundantly (∼1 star per square degree) along the galactic plane. We can detect it in the Galaxy up to several kpc from the sun on objective prism plates of the Schmidt telescope. We have been making survey observations of faint cool carbon stars using the Kiso 105-cm Schmidt telescope. Kodak IN and 103aF plates are respectively taken behind the 4-degree objective prism (700 Åmm−1 at Hα) for the detection and for the spectral classification. V-band plates are utilized to obtain the position and the brightness of the stars detected. The survey areas are distributed along the northern galactic plane. Seven fields in the Cassiopeia region (l = 115° to 133° and eight fields in the Taurus-Auriga-Gemini region (i = 170° to 188°) have been observed and processed up to now (Maehara and Soyano 1987a,b).