COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1108 Konkoly Observatory Budapest 1976 March 1 NEW VARIABLE STARS FOUND IN GALACTIC CLUSTERS The purpose of this note is to report the variability detected photoelectrically in fourteen stars located in the region of the following eight galactic clusters: Cr 132, Cr 140, Cr 228, Cr 240, Cr 367, NGC 3324, NGC 3590 and HOGG 10. All these clusters are being studied by the writer using wide-band (UBV) and narrow-band(HBeta) photometry. Observations of numerous stars in the region of all these clusters have been carried out during various observing runs in 1973-1975, using the 60-inch telescope of the Bosque Alegre Station of the Cordoba Observatory (Argentina) and the 24-inch Lowell and 36-inch telescopes of Cerro Tololo Inter-American Observatory (Chile). The observations were reduced using standard stars from the E-regions (1) and mean extinction coefficients. The external and internal mean errors of a single observation are about 0.01m in all the cases. Among the new variables detected there are ten having V amplitudes greater than 0.10m while the other four stars have deltaV variations in the interval 0.07m <= V <= 0.10m. Nine of the variable stars are undoubtedly cluster members, the remaining five being nonmember field stars. The individual UBV observations of the variable, stars detected in the fields of galactic clusters are listed in Table I whose columns give in succession: (1) HD/CD number or author's number, (2) indication if the star is a member (m) or non-member (n-m) of the cluster, (3) source of reference for the two former columns,(4) spectral type taken from the literature (2,3,4) or when given in parenthesis as estimated from the intrinsic UBV colours, (5) heliocentric Julian Date, and (6-8) magnitude and colours in the UBV standard system. A finding chart for the two variable stars in Cr 228 is shown in Fig. 1. JUAN J. CLARIA Centro de Investigacion de Astronomia F.J. Duarte. Apartado 264-Merida Venezuela Table I Individual UBV Observations of the New Variables Star Membership Ref. Sp.type HJD V B-V U-B 2440000+ Collinder 132 HD 56161 n-m 5 G5 IV 2427.572 6.88 0.76 0.32 2428.595 6.94 0.78 0.36 2431.603 7.18 0.64 0.36 2432.621 6.89 0.74 0.39 Collinder 140 HD 58535* m 5 gK 2 1686.588 5.32 1.08 0.92 1686.699 5.31 1.09 0.91 1686.821 5.32 1.08 0.91 1688.591 5.40 1.07 0.89 1688.721 5.41 1.05 0.91 1688.826 5.43 1.06 0.93 1691.564 5.34 1.08 0.89 1691.671 5.34 1.07 0.88 1691.798 5.34 1.07 0.87 1699.601 5.37 1.08 0.88 1699.725 5.37 1.08 0.89 1699.842 5.39 1.06 0.89 1769.621 5.34 1.06 0.88 1769.701 5.35 1.07 0.88 1770.703 5.35 1.08 0.89 2448.709 5.34 1.09 0.89 2449.601 5.39 1.06 0.88 2455.729 5.36 1.07 0.89 CD -31deg4410 n-m 5 - 2448.729 9.44 1.00 0.68 2449.643 9.51 0.92 0.72 2455.743 9.48 0.94 0.70 CD -31deg4409 m 5 (A7) 2448.688 10.26 0.19 0.16 2449.676 10.22 0.22 0.19 2455.779 10.29 0.24 0.18 2456.762 10.26 0.22 0.17 NGC 3324 28 m 6 (B2.5 V) 2449.794 12.14 0.24 -0.46 2450.800 12.34 0.22 -0.47 2451.818 12.27 0.25 -0.49 2452.818 12.21 0.24 -0.49 31 m 6 (B3 V) 2449.776 12.33 0.23 -0.43 2450.781 12.33 0.23 -0.42 2451.803 12.39 0.24 -0.41 2452.800 12.40 0.24 -0.42 Collinder 228 12* m 5 (B0) 1769.768 10.32 0.11 -0.73 1770.831 10.33 0.08 -0.76 2448.811 10.24 0.09 -0.76 36 n-m 5 - 1769.731 11.35 0.54 -0.02 1770.801 11.43 0.54 0.03 2448.796 11.28 0.58 0.06 Table I (continued) Star Membership Ref. Sp.type HJD V B-V U-B 2440000+ Hogg 10 7 m 7 (B2.5 V) 2449.701 12.15 0.23 -0.52 2450.711 12.30 0.25 -0.49 2452.710 12.25 0.28 -0.47 13 m 7 (B6 V) 2449.720 13.22 0.32 -0.24 2450.723 13.01 0.36 -0.20 2452.733 13.11 0.34 -0.20 Collinder 240 HD 97151 n-m 7 B2 Ve 2458.700 7.59 -0.05 -0.83 2459.728 7.70 -0.09 -0.80 2460.725 7.65 -0.10 -0.80 2462.731 7.64 -0.09 -0.82 HD 97013* m 7 O9.5 III 2458.709 8.77 0.20 -0.53 2459.716 9.02 0.25 -0.50 2460.733 8.84 0.24 -0.48 2462.739 8.88 0.24 -0.47 NGC 3590 22 n-m 7 - 2449.743 13.31 0.63 0.43 2450.739 13.46 0.56 0.39 2458.730 13.38 0.60 0.40 2462.759 13.39 0.60 0.40 Collinder 367 CD -24deg13962 m 5 O7.5nn 1897.635 7.34 0.12 -0.85 1898.643 7.32 0.15 -0.86 1899.659 7.29 0.14 -0.89 1900.663 7.38 0.11 -0.87 1920.703 7.45 0.11 -0.85 1921.691 7.36 0.13 -0.86 HD 58535: IDS double star (rho=1.9",Delta m=5.5). Measures refer to A component. Star 12(Cr 228): This star was also considered to be a cluster member by Feinstein et al.(8). HD 97013: From a recent study by Claria (7) it is suggested that the stars in the region of Cr 240 (=NGC 3572a) form an OB association rather than a cluster. [FIGURE 1] Figure 1 Finding chart for variables in Cr 228. References: 1) Cousins, A.W.J. 1972, M.N.R.A.S. Southern Africa, 31, 127 [BIBCODE 1972MNSSA..31..127C ] 2) Jaschek, C., Conde, H., and de Sierra, A.C. 1964, Catalogue of Stellar Spectra Classified in the MK System, La Plata Publ. Ser. Astr. 28, Part 2. 3) Kennedy, P.M. and Buscombe, W. 1974, MK Spectral Classification published since Jaschek's La Plata Catalogue, Evanston [BIBCODE 1974mscp.book.....K ] 4) Stephenson, C.B. and Sanduleak, N. 1971, Publ. Warner and Swasey Obs. 1, No. 1 [BIBCODE 1971PW&SO...1a...1S ] 5) Claria, J.J. (to be published) 6) Claria, J.J. 1976, Astron.& Ap.Suppl. (in press) 7) Claria, J.J. 1976, Astron. J. 81, 155 [BIBCODE 1976AJ.....81..155C ] 8) Feinstein, A., Marraco, H.G., and Forte, J.C. 1976, Astron. & Ap. Suppl. (in press)