[47.05] High Precision Photometry of Variable Stars in Clusters of Different Ages with the 1.3 m Robotically Controlled Telescope (RCT)

AAS 202nd Meeting, May 2003
Session 47 Robotic Astronomical Observatories
Topical Associated Poster, Wednesday, May 28, 2003, 10:00am-6:45pm, West Exhibit Hall

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[47.05] High Precision Photometry of Variable Stars in Clusters of Different Ages with the 1.3 m Robotically Controlled Telescope (RCT)

E.F. Guinan, G.P. McCook, L.E. DeWarf (Villanova Univ.), R.F. Gelderman, C.H. McGruder (Western Kentucky Univ.), D.K. Walter (S. Carolina St. Univ.), S.B. Howell, D.R. Davis, M. Everett (PSI), J.R. Mattox (Francis Marion Univ.)

We discuss a new program of carrying out high precision VRI CCD photometry of several star clusters of different ages. The photometry is being carried out using the 1.3 m Robotically Controlled Telescope (RCT), located at KPNO. This program focuses on the study of variable stars in mostly open clusters. Selected astrophysically important eclipsing binaries, pulsating variables, blue stragglers, and chromospherically active variable stars will be studied. Also, searches of new variable stars will be made from the expected large samples of cluster stars. For example, photometry is planned of the several W UMa eclipsing binaries and blue straggler stars in the old open cluster NGC 188. Photometry also will be carried out of the young open cluster NGC 7790. This cluster is unique because has three confirmed classical cepheid members: CE Cas A (V ~ +10.9 mag; F8 Ib; P = 4.446 d ), CE Cep B (V ~ +11.0 mag; F9 Ib; 5.128 d), and CF Cas (V ~ +11.1 mag; F8 Ib; 4.875 d). NGC 7790 also contains the 10th mag eccentric B0+B0 eclipsing binary QX Cas. The observations of QX Cas are being conducted to determine the accurate distance to this star and thus to the cluster and its cepheid members. When complete these observations, combined with spectroscopy, will permit a reliable calibration of the ``zero-point'' of the galactic cepheid Period-Luminosity Law. Another possible project is the search of light variations of PMS stars and chromospherically active stars (from star spot rotational modulations) in young clusters such as the alpha Perseus Cluster, h & \chi Per, M34, and the Pleiades.

Refurbishment of the RCT has been made possible by NASA grant NAG 58762. The RCT Consortium includes: Western Kentucky Univ., S. Carolina St Univ., Francis Marion Univ., Villanova Univ., and the Planetary Science Institute (PSI).

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