COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3560 Konkoly Observatory Budapest 4 February 1991 HU ISSN 0374 - 0676 BINARY SYSTEM 44i BOOTIS The binary system 44i Bootis was introduced in the photometric observational program of the Bucharest telescope in 1987, following the IAU indications, about the stars included in Hipparcos program (Dworak and Oblak, 1987). We have studied the light curve and the period change of this star. Using Duerbeck's ephemeris (1975) we obtained the (O-C) values for a lot of minima between 1975-1990 ((O-C)_1 in Table I). Figure 1 shows a period jump between 1977-1978 and we consider that a new jump was in 1986-1987. After the first jump we proposed a new period (Oprescu et al., 1989): Min I = 2443604d.5880 + 0.26781753d E. Using this new ephemeris we reconsidered the (O-C) values ((O-C)_2 in Table I). Figure 2 shows the new (O-C)_2 aspect. The proposed period was a good one for 1977-1987 interval. After 1987 a change in period was observed. Using a few observations between 1987-1990 we estimate this change: Delta P = 1.02666d * 10^-6 and the new ephemeris after 1987 will be: Min I = 2443604d.5880 + 0.26781856d E. The period change confirms the existence of "active" and "quiet" intervals in the life of this star. The active period is approximately 3 years and the duration of quiet period is about 7 years. The period change appears in an active interval. Table I. Hel.Min. (O-C)_1 E (O-C)_2 E Filter Authors 244... 2531.4512 -0.0015 10003 Duerbeck, 1985 2553.4119 -0.0017 10085 " 2837.5649 -0.0014 11146 " 2841.5831 -0.0004 11161 " 2953.5306 0.0000 11579 " 3604.5880 -0.0030 14010 Duerbeck et al. 1978 3607.5379 0.0009 14021 0.0020 11 " 3607.8107 0.0059 14022 0.0089 12 " 3614.3611 -0.0052 14046.5 -0.0022 36.5 Rovithis, 1981 3614.5000 -0.0002 14047 -0.0027 37 " 3615.5710 -0.0005 14051 0.0025 41 Rovithis, 1981 3616.3764 -0.0015 14054 0.0045 44 " 3974.4464 0.0019 15391 0.0024 1381 " 3974.5788 0.0001 15391.5 0.0010 1381.5 Hopp, Witzigmann, 1982 4706.5219 0.0023 18124.5 -0.0012 4114.5 " 4709.4679 0.0023 18135.5 -0.0012 4125.5 4345.5067 0.0030 16766.5 0.0016 2766.5 Mikolajewska, 4365.4569 0.0009 16851 -0.0006 2841 Mikolajewski, 4366.5290 0.0018 16855 0.0003 2845 1980 4349.3904 0.0034 16791 0.0020 2781 Bergeat et al., 1984 4351.5314 0.0019 16799 0.0004 2789 " 4354.4773 0.0017 16810 0.0003 2800 " 4355.5500 0.0032 16814 0.0017 2804 " 4356.3523 0.0020 16817 0.0006 2807 " 4366.7971 0.0020 16856 0.0005 2846 Scarfe et al., 1984 4390.9032 0.0047 16946 0.0030 2936 " 4409.7855 0.0060 17016.5 0.0042 3006.5 " 4811.7794 0.0082 18517.5 0.0040 4507.5 " 5473.8187 0.0076 20989.5 0.0085 6979.5 " 5476.9019 0.0099 21001 0.0018 6991 " 5477.8383 0.0090 21004.5 0.0008 6994.5 " 5478.7745 0.0078 21008 -0.0004 6998 " 5488.8162 0.0063 21045.5 -0.0018 7035.5 " 5468.4684 0.0126 20969.5 0.0045 6959.5 B Pohl, Tunca, 1985 5468.4649 0.0091 20969.5 V " 5482.5245 0.0084 21022 0.0002 7012 B " 5482.5259 0.0098 21022 V " 5870.4565 0.0111 22470.5 -0.0015 8460.5 V " 6640.3026 0.0174 25345 0.0033 11335 B Al-Naimiy et al., 6638.2937 0.0171 25337.5 0.0030 11327.5 B 1986 6640.3005 0.0153 25345 V " 6638.2939 0.0151 25337.5 V " 6973.3286 0.0153 26588.5 U Oprescu et al., 1989 6973.3296 0.0163 26588.5 0.0006 12578.5 B " 6973.3352 0.0218 26588.5 V " 6977.3550 0.0245 26603.5 0.0074 12593.5 U " 6977.3510 0.0205 26603.5 B " 6977.3557 0.0252 26603.5 V " 6984.3159 0.0221 26629.5 0.0050 12619.5 U " 6984.3174 0.0236 26629.5 B " 6984.3235 0.0298 26629.5 V " 6986.3253 0.0229 26637 0.0058 12627 U " 6986.3238 0.0214 26637 B " 6986.3257 0.0233 26637 V " 7242.4883 0.0200 27593.5 0.0013 13583.5 Rovithis 7242.6248 0.0224 27594 0.0039 13584 Rovithis-Livaniou, 7245.4395 0.0252 27604.5 0.0066 13594.5 " 7245.5701 0.0219 27605 0.0032 13595 " 7319.7446 0.0114 27881 U Willmitch, 7319.7495 0.0173 27881 B Douglas, 1989 7319.7491 0.0159 27881 B " 7322.7008 0.0217 27892 B " 7322.6999 0.0208 27892 V " 7338.3675 0.0211 27951 0.0019 13941.5 Rovithis, 7338.5006 0.0203 27952 0.0011 13942 Rovithis-Livaniou, 7340.3756 0.0206 27959 0.0013 13949 1989 7341.3174 0.0250 27962.5 0.0058 13952.5 " 7341.4445 0.0182 27963 -0.0010 13953 " 7359.3920 0.0221 28030 0.0027 14020 Surkova, 1990 7364.3469 0.0224 28048.5 0.0030 14038.5 " 7365.4180 0.0223 28052.5 0.0028 14042.5 " 7371.4438 0.0222 28075 0.0027 14065 " 7375.3270 0.0220 28089.5 0.0026 14079.5 " 7388.3163 0.0223 28138 0.0027 14128 " 7393.4050 0.0225 28157 0.0029 14147 " 7739.2988 0.0320 29448.5 0.0104 15438.5 V This paper 8086.3840 0.0278 30744.5 0.0041 16734.5 U " 8086.3881 0.0319 30744.5 0.0062 16734.5 B " 8086.3877 0.0315 30744.5 0.0078 16734.5 V " 8091.3346 0.0238 30763 0.0001 16753 U " 8091.3346 0.0238 30763 0.0001 16753 B " [FIGURE 1] [FIGURE 2] GABRIELA OPRESCU MARIAN DORU SURAN NEDELIA POPESCU Astronomical Institute of Romanian Academy 7000 Bucharest, Cutitul de Argint 5 References: Bergeat, J., Lunel, M., Garnier, R.: 1984, IBVS, No. 2570. Duerbeck, H.W.: 1975, IBVS, No. 1023. Duerbeck, H.W., Karimie, M.T., Hopp, U., Kiehl, M., Witzigmann, S.: 1978, IBVS, No. 1497. Dworak, T.Z., Oblak, E.: 1987, IBVS, No. 2991. Al-Naimiy, H.A., Fleyeh, H.A., Al-Sikab, A.O., Al-Razzaz, J.M.: 1986, IBVS, No. 2956. Hopp, U., Witzigmann, S.: 1982, Astrophys. Space Sci., 83, 171. [BIBCODE 1982Ap&SS..83..171H ] Mikolajewska, J., Mikolajewski, M.: 1980, IBVS, No. 1812 Oprescu, G., Suran, M.D., Popescu, N.: 1989, IBVS, No. 3368. Pohl, E., Tunca, Z.: 1985, IBVS, No. 2793. Rovithis, P.: 1981, Astrophys. Space Sci., 76, 351. [BIBCODE 1981Ap&SS..76..351R ] Rovithis, P., Rovithis-Livaniou, H.: 1989, IBVS, No. 3339. Scarfe, C.D., Forbes, D.W., Delaney, P.A., Gagne, J.: 1984, IBVS, No. 2545. Surkova: 1990, IBVS, No. 3435. Willmitch, T., Douglas, H.: 1989, IBVS, No. 3318.