COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2612 Konkoly Observatory Budapest 22 October 1984 HU ISSN 0374 - 0676 OUTBURSTS OF THE STAR CASE 1 The object Case 1 (alpha = 12h13m16s; delta= +52d47.5'; 1950.0) is a close pair consisting of a DA white dwarf and a dM4e red dwarf (Lanning and Pesch, 1981). Lanning (1982) found that the radial velocity of the H_alpha line varies with the period 0.66765d and the semiamplitude is K = 116 km/s. The period he found is apparently the orbital period in the close binary system. However, the author was not able to find any considerable variability. The star was investigated using 430 plates of the Sternberg Institute plate collection taken in the interval J.D.2 437462 - 2445 854 and three more plates (J.D. 2 418 771 - 2 419 126). The identification chart for the object is shown in Fig. 1. Table I gives photoelectric UBV-measures of neighbour stars. Our plate material shows minor brightness changes in the range 13.6 - 13.9B , which is comparable with the errors of photographic photometry. It was, however, possible to find two reliable outbursts to 13m B.The moments of the outbursts an adjacent observations are given in Table II. Table 1 ------------------------------ stars V B-V U-E ------------------------------ 1 7.54 +1.06 +0.87* 2 11.62 +0.66 +0.20** 3 12.27 +0.55 +0.03 4 12.54 +1.55 +1.0 [FIGURE 1] 5 12.80 +0.58 -0.04 6 13.00 +0.59 +0.03 7 13.24 +0.75 +0.15 8 13.83 +0.71 +0.11 ------------------------------ * BD+ 53d1535 ** the standard star for photoelectric observations The occurrence of outbursts could be explained by an increase of the rate of accretion on the white dwarf, probably from the thin disk surrounding it. Thus the system is semidetached or almost semidetached, since there Table II --------------------------------------------- J.D. B J.D. B --------------------------------------------- 2438139.370 13.69 2439919.316 13.62 142.360 13.02 936.320 13.18 142.391 13.12 937.304 13.84 145.342 13.67 --------------------------------------------- Table III ----------------------------------------- J.D. V B-V U-B ----------------------------------------- 2445852.319 13.25 +0.54 -0.49 854.328 13.21 +0.53 -0.49 858.302 13.25 +0.56 -0.46 858.308 13.23 +0.54 -0.44 858.322 13.24 +0.54 -0.45 858.337 13.24 +0.53 -0.44 858.345 13.20 +0.54 -0.42 858.356 13.20 +0.58 -0.45 ----------------------------------------- appears a possibility of accretion of matter from the cooler star onto the hot one. Our photoelectric observations are given in Table III where no noticeable variability is apparent. Eggen and Greenstein (1965) give the following values for the variable: V = 13.34m ; B-V = +0.53m ; U-B = -0.48m. It is worth noting that the star No. 4 on our chart is possibly a slow variable with an amplitude not exceeding 1m. The author is grateful to V.P. Goranskij and N.V. Metlova for their assistance during observations and reductions. S. YU. SHUGAROV Moscow State University Sternberg Astronomical Institute Moscow, U.S.S.R. References: Eggen, O.J., and Greenstein, J.L., 1965: Astrophys. J., 141, 83, [BIBCODE 1965ApJ...141...83E ] Lanning, H.H., 1982: Astrophys. J., 253, 752. [BIBCODE 1982ApJ...253..752L ] Lanning, H.H., and Pesch, P., 1981: Astrophys. J., 244, 280. [BIBCODE 1981ApJ...244..280L ]