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Planets in Stellar Clusters Extensive Search. V. Search for Planets and Identification of 18 new Variable Stars in the Old Open Cluster NGC 188

Mochejska B. J., Stanek K. Z., Sasselov D. D., Szentgyorgyi A. H., Cooper R. L., Hickox R. C., Hradecky V., Marrone D., P., Winn J. N., Schwarzenberg-Czerny A.

Acta Astronomica

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2008

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Vol. 58, No. 3

263--278

EN

We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 188, an old, rather populous cluster. We have monitored the cluster for more than 87 hours, spread over 45 nights. We have not detected any good transiting planet candidates. We have discovered 18 new variable stars in the cluster, bringing the total number of identified variables to 28, and present for them high precision light curves, spanning 15 months.

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Variable Stars in the Field of the Globular Cluster E3

Mochejska B. J., Kaluzny J., Thompson I.

Acta Astronomica

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2000

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Vol. 50, No. 1

105--111

EN

We present the results of a search for variable stars in the faint sparse globular cluster E3. We have found two variable stars: an SX Phe variable (V1) and a W UMa eclipsing binary (V2). We have applied period-luminosity and period-color-luminosity relations to the variables to obtain their distance moduli. V1 seems to be a blue straggler belonging to E3, based on its distance modulus and location in the CMD. V2 is probably located behind the cluster, in the Milky Way halo. We also present V/B-V and V/V-I color magnitude diagrams of E3.

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Variable Stars in the Field of the Open Cluster NGC 7789

Mochejska B. J., Kaluzny J.

Acta Astronomica

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1999

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Vol. 49, No. 3

351--370

EN

We present the results of our search for variable stars in the intermediate-age open cluster NGC 7789. We have found 45 variable stars: 35 eclipsing binaries, five pulsating variables and five miscellaneous variables. Most of the eclipsing binaries show W UMa type of variability, with periods shorter than one day. Four systems exhibit unusual behavior: two, V8 and V32, are probably RS CVn stars, another, V9, is a possible cataclysmic binary. The nature of the fourth binary, V4, is unclear: the system exhibits asymmetric maxima. Among the pulsating variables two, V44 and V45 are background RR Lyrae stars and one, V10, is a δ Sct variable which is a blue straggler belonging to the cluster. Some of the miscellaneous variables may have periods longer than the five day timespan of our observations. We also present a color-magnitude diagram for the NGC 7789 open cluster, fairly complete down to V≈20. The relatively large number of variables found in the comparison field (14 compared to 31 in the cluster field) implies that objects not associated physically with the cluster can account for a significant number of variables identified in the cluster field, as well as in other globular and open clusters observed on a dense background/foreground of disk stars.

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Identification and Photometry of Globular Clusters in M31 and M33 Galaxies

Mochejska B. J., Kaluzny J., Krockenberger M., Sasselov D. D., Stanek K. Z.

Acta Astronomica

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1998

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Vol. 48, No. 3

455--488

EN

We have used the data from the DIRECT project to search for new globular cluster candidates in the M31 and M33 galaxies. We have found 67 new objects in M31 and 35 in M33 and confirmed 38 and 16 previously discovered ones. A VI and BVI photometry has been obtained for all the clusters in M31 and M33, respectively. Luminosity functions have been constructed for the clusters in each galaxy and compared with that of the Milky Way.