AAS Meeting #193 - Austin, Texas, January 1999
Session 68. Globular Clusters
Display, Friday, January 8, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[68.06] A direct determination of the parameters for two upper-main sequence stars in the globular cluster \omega~Centauri

J. Kaluzny (Warsaw University Obs.), I. Thompson (Carnegie Inst. of Washington), W. Pych (Warsaw University Obs.), W. Krzeminski (Carnegie Inst. of Washington)

We present the first results of a project aimed at the direct determination of the absolute parameters of turn-off stars in nearby globular clusters. The results of our program will allow in turn the determination of ages and distances of globular clusters. We have used the 2.5-m du Pont and and 4-m Blanco telescopes to obtain CCD light and echelle radial velocity curves for OGLEGC-17, a detached eclipsing binary located in the field of \omega~Centauri. The radial velocity of the system is determined to be -233 km/sec and confirms its cluster membership. Analysis of the eclipse light curves and the radial velocity curves leads to a measurement of the masses and radii of the components of this double-lined binary.The more massive component is just leaving the main-sequence of the cluster. Its mass and radius are m1=0.78 m\odot and R1=1.87 R\odot. The less massive component is an upper-main sequence star with a mass m2= 0.68 m\odot and a radius R2=0.89 R\odot.

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The author(s) of this abstract have provided an email address for comments about the abstract: jka@sirius.astrouw.edu.pl

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