COMMISSIONS 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3749 Konkoly Observatory Budapest 10 July 1992 HU ISSN 0374 - 0676 V2101 OPH IS NOT A CATACLYSMIC VARIABLE The star V2101 Oph, originally discovered by Woods (1926) and reanalyzed by Swope (1932) has been analyzed using photographic plates taken at the Crimean Astronomical Laboratory, between 1960 and 1991, on the 40 cm Astrograph in B light. The data were reduced at the Sternberg Astronomical Institute. This star was previously classified as a dwarf nova, type U Geminorum (GCVS 4th Edition). After the reduction of data using the Deeming (1975) and Lafler-Kinman (1965) methods for determining the period, a best period of 240 days was found. The light curve of the star folded with the period of 240d is shown in Figure 3. A better analysis, using windows of data shows increases and decreases of brightness near the star's maximum (Figure 2). A comparison of the POSS blue and red prints (-24 16h54m) shows that the star is clearly red, where on the blue print m_B = 17.12. On the POSS (-30 16h54m) the data is ambiguous (Samus, private communication); so it is not clear that the star is "bright blue" as stated by Vogt and Bateson (1982). Considering this, and that at the maximum, m_pg,R = 12.5 (Terzan and Ounnas, 1988) and m_pg,B = 13.33, we conclude that this star is a red, long period star (type Mira). Independent works have shown that the color variations are not typical of U Gem, that the brightness increase roaches its maximum in B and decreases to R (Yakubov et al., 1992), and that its spectrum is a late type one with strong TiO bands fitting an M5 II-III type (Claudi and Bianchini, 1992) what reinforces our conclusion. [FIGURE 1] Figure 1. a.) Finding chart of V2101 Oph, b.) Magnitudes of the comparison stars B b 12.49 c 14.43 d 15.8 e 16.4 Table I. Photographic observations of V2101 Oph J.D.24... B J.D.24... B J.D.24... B 37109.430 14.66 44819.300 16.72 46944.460 17.92 130.350 14.27 820.290 16.72 945.450 <15.5 138.320 13.88 45087.520 15.06 977.350 16.72 139.340 14.27 134.410 14.66 978.370 16.72 144.340 14.27 464.520 <16.7 47264.570 13.88 145.330 14.66 469.520 <16.7 329.410 17.12 40738.500 16.72: 494.430 <17.5 383.290 <16.7 745.440 <16.7 496.420 <16.7 620.560 <16.7 43989.520 16.72 .450 <16.7 626.540 <16.7 992.520 17.12 499.410 <16.7 681.460 <17.1 993.450 16.72 523.380 17.12 682.440 16.72 994.550 <15.5 546.320 <16.7 716.320 14.66 44015.450 17.52 552.300 <15.5 .340 14.57 020.440 <16.7 823.510 13.33 717.350 14.66 023.430 <16.7 .530 13.49 740.340 13.75 028.430 <15.5 824.520 13.33 48028.410 16.29 041.380 <16.7 825.520 13.49 029.430 16.29 406.380 13.88 826.530 13.49 033.450 16.29 409.110 13.88 846.420 14.27 034.460 16.40 410.390 13.88 849.460 13.88 035.410 16.72 430.360 14.66 852.460 14.66 037.390 16.72 435.340 14.86 873.390 17.12 389.500 17.12 438.360 15.05 875.400 <17.1 394.470 16.72 789.360 <15.5 876.360 16.72 418.420 14.86 811.320 <15.5 884.370 17.12 423.410 14.66 812.310 17.52 46204.470 <15.5 425.410 14.66 813.310 17.12 209.460 <16.7 426.410 13.88 815.300 <16.7 256.370 17.12 448.380 13.22 818.310 <16.7 589.420 16.29 454.340 13.75 The magnitudes of the comparison stars were obtained by comparison with the standard sequence in the field of V2051 Oph (Meech,1983) and are listed in Figure 1b. Figure 1a contains the finding chart of V2101 Oph. Table I lists the Julian Dates and the observed B magnitudes. [FIGURE 2] Figure 2. Variation of brightness around a maximum [FIGURE 3] Figure 3. Light curve for P=240.3d with the initial maximum at J.D. 2448450 Besides the data listed in Table I, data from Yakubov et al. (1992) obtained in 1991 were also used in order to find the light curve shown in Figure 3, where the different sets of data are marked with the same symbol. The author would like to thank Dr. N.N. Samus and especially Mr. A.Yu. Pogosiants for their help and guidance throughout this project, and L.V. Jones for the helpful comments and useful discussions. RENATO A. DUPKE Sternberg Astronomical Institute Moscow State University Universitetskij Prospect, 13 Moscow 119899, Russia E-mail: SNN @ SALMSK.SU Subject: For Renato Dupke References: Claudi, R.U., Bianchini, A.: 1992, IBVS No. 3716 Deeming, T.J.: 1975, Astrophys. Space Sci., 36, 137 [BIBCODE 1975Ap&SS..36..137D ] Lafler, J., Kinman, T.D.: 1965, Astrophys. J. Suppl. Ser., 11, 216 [BIBCODE 1965ApJS...11..216L ] Meech, K.J.: 1983, P.A.S.P, 95, 662 [BIBCODE 1983PASP...95..662M ] Swope, H. H.: 1932, Harvard Bull., No. 887 Terzan, A., Ounnas, Ch.: 1988, As. Ap. Suppl. Ser., 76, 205 [BIBCODE 1988A&AS...76..205T ] Vogt, N., Bateson, F.N.: 1982, As. Ap. Suppl. Ser., 48, 383 [BIBCODE 1982A&AS...48..383V ] Woods, I.: 1926, Harvard Bull., No. 834 Yakubov, S.D., Ibragimov, M.A. and Skornyakova, S.A.: 1992, IBVS No. 3707