COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2091 Konkoly Observatory Budapest 1982 February 19 HU ISSN 0374-0676 PS4452-1347 * - A NEW RR Lyr VARIABLE STAR OF BAILEY TYPE C In a search programme for field population II A and F stars with visual magnitudes between 13m and 16m in high galactic latitudes, extending a pilot project reported on by Crawford et al. (1979), simultaneous photoelectric photometry in the Stromgren uvby photometric system (Stromgren, 1966) has now been carried out for 275 candidate stars in two observing periods in 1980 and 1981 with the Danish 1.5-m telescope at ESO, La Silla (Andersen, 1982). One of these stars, PS4452-1347, was, based on three observations in October 1980, suspected for variability and observed systematically on six consecutive nights in August 1981 along with other programme and standard stars. The reduction of these observations shows that the star is an RR Lyr variable with a nearly sinusoidal lightcurve indicating a Bailey type c; the period is 0.381 d and the mean visual magnitude is 13.53. The star is not included in the General Catalogue of Variable Stars (Kukarkin et al., 1969) nor in the subsequent name-lists of variable stars (Kukarkin et al., 1970-1977; Kholopov et al., 1978-1981). The star PS4452-1347 (alpha_1950 = 0h24m30.13s , delta_1950= + 0d23'54.9", epoch 1960.64) was observed 34 times during the six nights, each observation consisting of 3 to 4 60-second integrations. Table I gives the 34 observations reduced to visual magnitudes on the Johnson system and indices on the standard system of Crawford and Barnes (1970). Typical mean * Star no. 1347 measured on Palomar Schmidt plate no. 4452. Table I ------------------------------------------------------- Helioc. JD -2440000 V b-y m1 c1 Phase ------------------------------------------------------- 4839.7790 13.403 .181 .091 1.152 .158 4839.8157 13.521 .212 .080 1.043 .255 4839.9255 13.717: .307: .030: 1.092: .543 4840.7090 13.699 .246 .079 .897 .599 4840.7667 13.477 .193 .095 1.039 .750 4840.8861 13.240 .169 .094 1.190 .064 4841.6664 13.367 .172 .094 1.177 .111 4841.7577 13.641 .237 .080 .988 .351 4841.8105 13.765 .262 .067 .890 .489 4841.8297 13.741 .253 .076 .895 .540 4841.8795 13.650 .230 .081 .960 .670 4842.6577 13.616 .211 .085 .962 .713 4842.6838 13.455 .185 .092 1.066 .781 4842.7450 13.322 .168 .097 1.127 .942 4842.7836 13.299 .170 .086 1.206 .043 4842.8306 13.401 .192 .084 1.155 .166 4842.8517 13.472 .197 .095 1.112 .222 4842.8786 13.564 .218 .087 1.045 .292 4843.6542 13.642 .221 .090 .989 .327 4843.6933 13.741 .241 .090 .906 .430 4843.7381 13.772 .251 .080 .895 .548 4843.7881 13.691 .219 .095 .948 .679 4843.8284 13.456 .170 .100 1.085 .785 4843.8485 13.411 .173 .095 1.083 .837 4843.8762 13.331 .176 .087 1.110 .910 4843.8982 13.328 .157 .105 1.189 .968 4844.7170 13.358 .175 .090 1.193 .116 4844.7304 13.386 .186 .084 1.178 .152 4844.7382 13.405 .191 .081 1.168 .172 4844.7415 13.438 .182 .095 1.155 .181 4844.7535 13.469 .199 .084 1.129 .212 4844.7634 13.518 .201 .088 1.104 .238 4844.7946 13.640 .234 .081 .984 .320 4844.8094 13.703 .227 .095 .957 .359 Mean 13.531 .205 .089 1.050 Beta = 2.706 Amplitude .476 .100 .024 .286 ------------------------------------------------------------ [FIGURE 1] errors of one observation in V, b-y, m_1 and c_1 are 0.008, 0.006, 0.009 and 0.010, respectively. It was found that the instrumental magnitudes u, v, b, y, could each be accurately fitted with a pure sine curve with no significant difference in period, and in this way a period P = 0.38108d +- 0.00020d (m.e.) has been determined. The epoch of maximum is given by the expression Max = 2 444 839.7186 + 0.38108 E . In Figure 1 we give the observed V-light curve along with the observed (b-y)-, m_1-, and c_1-colour curves. Also shown is the sine curve best fitting the V observations. In Table I we have also given the mean magnitude and colours and the respective full amplitudes as determined from the optimum sine curves. The mean value of a few Hbeta-observations is also given. The observations indicate a mean spectral type around F0. Assuming a mean absolute visual magnitude of +0.5m, the star is located at a distance of 4.0 kpc, i.e., 3.6 kpc from the galactic plane. T.B. ANDERSEN Copenhagen University Observatory Oster Voldgade 3 DK-1350 Kobenhavn K, Denmark References: Andersen, T.B., 1982, in preparation. Crawford, D.L., Barnes, J.V., 1970, Astron. J. 75, 978. [BIBCODE 1970AJ.....75..978C ] Crawford, D.L., Mavridis, L.N., Stromgren, B., 1979, Abh. Hamburger Sternwarte, Band X, 82. Kholopov, P.N., et al., 1978-1981, IBVS No.s 1414, 1581, 1921. Kukarkin, B., et al., 1970-1977, IBVS No.s 480, 717, 834, 961, 1068, 1248. Kukarkin, B., et al., 1969, General Cat. Variable Stars, Moscow. Stromgren, B., 1966, Ann., Rev. Astron Astroph. 4, 433. [BIBCODE 1966ARA&A...4..433S ]