A new variable star in the Cepheus region

Download A new variable star in the Cepheus region

Post on 10-Jul-2016




2 download


Astrophysics, Vol. 38, No. 4, 1995 A NEW VARIABLE STAR IN THE CEPHEUS REGION N. D. Melikian and A. Ts. Karapetian A new variable star has been discovered in the Cepheus region during spectral observations of dark cloud regions. The observetions were carried out with the 40" Schmidt telescope of the Byurakan Observatory. The spectral plates were obtained by the 4* objective prism (I 100 A/mm at H a) on Kodak 103aF and 103aE emulsions through RG610 and RG2 f'dters. The limiting photographic magnitude of our observations was about 18.5. The different exposures and epochs of observations have allowed us to detect the light variations of stars and variation of intensity of the H a emission line during the observational period. During 1979-1989 at the Byurakan Astrophysical Observatory 14 dark clouds regions were observed and about 100 new H a emission stars were discovered in three regions [1-3]. Altogether in these regions a few hundred H a emission stars were already known. In the next two regions 130 new H,~ emission stars were discovered. In one of these regions a new variable star was detected on the spectral plates obtained in 1985. In 1985 three plates were obtained for this region: two plates on August 23 and one on September 8. On the last plate a brightness variation of the star was detected. In Table 1 the following data for this star is presented: coordinates (1950.0), red magnitude of the star (mr) at minimum of brightness, and the amplitude of variation (AR). TABLE 1. Data for the New Variable Star a(195o) 8(195o) m &R 21 10.5 52 55.5 17.5 1.5 .-' :.:i':"" "~'. : " +;. ". "" ::" ::'-'~ ~ ;~: :~;~: .~ '~,~!;" ~?In Fig. la, b the star images from the spectral plates obtained in 1985 are shown. As one can see in Fig. lb, a very strong H a emission line exists. On the plates obtained in 1979 the star is again in the minimum without H~, emission. This star is in Cepheus region. If the distance of the star is the same as for the association Cep OB2 [4], its absolute magnitude will be Mpg = 8. A star with such an absolute magnitude can be a red dwarf and in all probability is a flare star. REFERENCES . 2. 3. 4. N. D. Melikian, V. S. Shevchenko, and S. Yu. Melnikov, IBVS, No. 3073 (1987). N. D. Melikian and V. S. Shevchenko, AstrofLzika, 32, 169 (1990). N. D. Melikian, Astrofizika (1994), in press. S. C. Simonson, Astrophys. J., 154, 923 (1968). 397