COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2115 Konkoly Observatory Budapest 1982 March 23 HU ISSN 0374-0676 VARIABLE STARS IN THE PLEIADES CLUSTER II From 1981 October 18 till November 17 we performed photometry on 16 K-type stars in the Pleiades cluster. All of these stars were known or suspected to be variable on the basis or earlier work. Five of the stars were also measured a year before by Alphenaar and Van Leeuwen (1981, hereafter referred to as Paper I). The other 11 stars formed a new selection. All stars were measured using the Walraven photometer and the Dutch 91 cm telescope at La Silla, ESO (Lub, 1979). Positions and search maps of the previously measured stars can be found in Paper I, those for the new selection are given in Fig. 1. The diameter of each field is 12 arcmin and the magnitudes indicated are photographic magnitudes. The limiting magnitude is around m_pg= 14.5. Table I lists the measured stars and their visual magnitudes. The star numbers are from Hertzsprung (1947). Ten of the eleven newly selected stars were found to be. variable and for the other, Hz883, no conclusions could be drawn. For 7 of these stars periods and lightcurves could be obtained, as well as for the 5 remeasured stars. All lightcurves and periods are presented in Fig. 2a, 2b, 2c and 2d as differences in 10log(I) for the V channel. between the given star and the substandard for the cluster, Hz804. The zeropoints for the phase calculations are at JD=2444896.5. The periods of the five previously measured stars did not need to be changed. For Hz879 the shorter period given in Paper I turned out to be the right one. The lightcurve of Hz1883 was repeated accurately, but for all others there seem to be disturbing sources active. The 7 new stars for which periods and lightcurves were obtained are also of the BY Dra type. Four of them; viz. Hz882, 1531, 2034 and 3163, resemble the lightcurve of Hz1883. Hz625 shows a broader minimum than the other stars. The small amplitudes of the stars Hz1039 and 1332 do not permit detailed interpretation. Five of the new selection of stars, viz. Hz451, Hz883, Hz1039, Hz1531 and Hz2034, are known as flare stars (Haro, 1976). [FIGURE 1] [FIGURE 1b] Table I, Measured Stars --------------------------- Hz m_v (V-B) --------------------------- 34 12.06 .43 451 13.43 .57 625 12.66 .53 659 12.02 .41 686 13.44 .52 879 12.83 .50 882 12.90 .49 883 13.05 .53 1039 13.05 .57 1124 12.32 .44 1332 12.52 .47 1531 13.58 .56 1883 12.61 .48 2034 12.65 .45 3019 13.49 .57 3163 12.73 .46 ------------------------- [FIGURE 2a] [FIGURE 2b] [FIGURE 2c] [FIGURE 2d] In a recent letter to Astronomy and Astrophysics the observations presented here and in Paper I are discussed in more detail, including also some spectroscopic data. J.J.M. MEYS, P. ALPHENAAR F. van LEEUWEN Sterrewacht Leiden Royal Greenwich Observatory Postbus 9513 Herstmonceux Castle 2300 RA Leiden Hailsham, East Sussex The Netherlands BN27 1RP England (also address for correspondence) References: Alphenaar, P. and Van Leeuwen, F.: 1981, IBVS 1957 Lub, J.: 1979, ESO Messenger 19, 1 [BIBCODE 1979Msngr..19....1L ] Haro, G.: 1976, Ton. Obs. Bol. 2, 3 [BIBCODE 1976BITon...2....3H ] Hertzsprung, E.: 1947, Leiden Annalen 19 part A [BIBCODE 1947AnLei..19A...1H ]