COMMISSIONS 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3852 Konkoly Observatory Budapest, 1 March 1993 HU ISSN 0374 - 0676 LIGHTCURVE AND PERIOD OF THE SYSTEM V450 HERCULIS Discovered in 1955 by Geyer (1955, 1963) on Bamberg plates, the star BD+34d 2831 has been given the provisional designation BV 104. The system was classified as EA type star with a period of 0.912718d and light variations ranging from 10.1 to 10.65m (pg). No secondary minimum could be detected and the eclipse duration was given 2.6h. In 1968 the list of pg. minima was extended by H. Bauernfeind (Geyer, 1968). A period lengthening of 0.15s after JD 2425000 was assumed. This leads to the elements Min.=JD 2425687.585+0.912729d x E (I) In the years 1984-85 and 1988-90 the star was observed photoelectrically with a DC photometer attached to the 34cm Cassegrain at the Nurnberg Observatory. The measurements were made through the V filter and are given in the instrumental system. BD +34d 2829 was taken as the comparison star. This choice could not be recommended because of the large B-V index as compared with the variable, whose spectral type was determined as A0 by Gotz and Wenzel (1962). BD +34d 2832 was chosen as the check star. Throughout the observation period, the magnitude difference check - comparison remained constant. Each point in the lightcurve (Figure 1) is the mean of five consecutive measurements. The standard deviation of 91% from a total of 132 points fell down to a limit of +-0.020m with a neat maximum of the error distribution in the 0.010m to 0.015m range. The 1984-85 observations confirmed roughly the Bamberg period, but the long eclipse duration (D=0.38p) led us to the conclusion that the period must be doubled. The lightcurve (Figure 1) shows two nearly equal partial eclipses with an amplitude of 0.31m, so that the minima attribution in Table 1 is arbitrary. The EA-type classification could be confirmed. The system shows a marked reflection effect with an additional brightening amounting up to 0.050m at maximum phases. Both short and long time-scale variations in the reflection phase may be present if the 1985 and 1988-90 lightcurves are compared (Grobel and Lichtschlag, 1991). The V magnitude of the nearby star BD +34d 2830 is 5.99m (Papousek, 1988). The magnitude of the comparison could be determined as 9.73+-0.007m. Therefore V450 Her varies within the limits 10.26m to 10.64m (V). In the O-C diagram (Figure 2) three observation periods could be discerned: 1. From JD 15000 to 34000: A total of 11 normal minima, each consisting of 9 to 10 observations, could be calculated. The period lengthening around JD 25000 could not be confirmed. The period of 0.9127221d derived from that data failed to reproduce later observations. 2. From JD 38000 to 44000: These minima were found by Berthold (1982) on Hartha survey plates. Two normal minima from 6, resp. 5 observations could be calculated. The period of the elements Min.=2444635.591+0.9127152dxE (II) is a little bit too short to represent all available minima. [FIGURE 1] Figure 1. The differential V lightcurve of V450 Her. [FIGURE 2] Figure 2. The O-C diagram for the year 1902 to 1992. Table 1 The residuals of the pg. normal minima and pe. minima in the column O-C_III were calculated with half the period given in elements (III). Minimum (O-C)I (O-C)II Ep.III (O-C)III Min. Reference 1 15959.791 0.092 -0.114 -33150 -0.055 (5,6,7) 2 17497.727 0.079 -0.103 -31465 -0.049 " " 3 19518.518 0.088 -0.063 -29251 -0.015 " 4 22419.105 0.023 -0.085 -26073 -0.044 " " 5 26033.518 0.029 -0.025 -22113 0.007 " " 6 26780.079 -0.023 -0.065 -21295 -0.036 " 7 27361.464 -0.046 -0.079 -20658 -0.052 " " 8 28112.708 0.022 0.000 -19835 0.026 " 9 28657.581 -0.004 -0.018 -19238 0.006 " 10 29388.690 0.009 0.006 -18437 0.028 " " 11 32040.139 -0.020 0.018 -15532 -0.032 " " 12 39083.527 -0.162 -0.017 -7815 -0.022 (3) 13 43486.488 -0.205 0.005 -2991 -0.011 " " 14 45903.3733 -0.226 0.021 -343 -0.0025 Min.II pres. paper 15 46216.4380 -0.228 0.024 0 0.0000 Min.I pres. paper 16 47239.5904 -0.244 0.023 1121 -0.0041 Min.II " " 17 47239.5904 -0.243 0.024 1121 -0.0031 Min.II (1) 18 47616.5465 -0.245 0.028 1534 -0.0004 Min.I (10) 19 47669.467: -0.263 0.011 1592 -0.017: Min.I pres. paper 20 47670.3977 -0.245 0.029 1593 0.0004 Min. II pres. paper 21 48496.414: -0.269 0.038 2498 0.0072 Min.I (2) 3. After JD 45000: In addition to the pe. observations, some visual minima are plotted in the O-C diagram (Brelstaff, 1985, Kucera, 1986). The two last observation periods are shifted against the first one, but it is rather improbable that a period change occurred in the remaining observational gap. A search for additional pg. minima will be useful to verify this assumption. For the present, it could be assumed that no significant period change has occurred since the beginning of the observations, contradicting the conclusions of Srivastava (1991). A mean period derived from Table 1 and the proposed doubling of the period leads to the elements Min. I. (hel.)=JD 2446216.4380+1.8254354dxE (III) We would like to thank some members of the Nurnberg astronomical working group (NAA) for assistance during the measurements. Rainer GROBEL Gerald LICHTSCHLAG Nurnberg Observatory Regiomontanusweg 1 8500 Nurnberg 20 F.R.G. References: (1) Agerer, F., 1988 BAV Mitteilungen, 50 (2) Agerer, F., 1992 BAV Mitteilungen, 60 (3) Berthold, T., 1982, Mitt. Bruno-H.-Brugel-Stw. Hartha, 17, 14 (4) Brelstaff, T., 1985, BAA V.S.S. Circ., 59, 60, 61 (5) Geyer, E., 1955, Kl. Veroff. Remeis Stw. Bamberg, 11 (6) Geyer, E., 1963, Veroff. Remeis Stw. Bamberg, V, 16 (7) Geyer, E., 1968, Veroff. Remeis Stw. Bamberg, VII, 72 (8) Gotz, W., Wenzel, W., 1962 Mitt. fur Ver. Sterne, I, 702 (9) Grobel, R., Lichtschlag, G., 1991, BAV Rundbrief, 40, 1 [BIBCODE 1991BAVRu..40....1G ] (10) Keskin, V. et al., 1989, IBVS, No. 3355 (11) Kucera, P., 1986, Brno Contributions, 28 (12) Papousek, J., 1988, private communication (13) Srivastava, R. K., 1991, Astr. Sp. Sci., 181, 7 [BIBCODE 1991Ap&SS.181....7S ]