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| Paper: |
Variable Stars in the Draco Dwarf Spheroidal Galaxy |
| Volume: |
92, Formation of the Galactic Halo. . . . Inside and Out |
| Page: |
536 |
| Authors: |
Silbermann, N. A.; Harris, Hugh C.; Smith, Horace A. |
| Abstract: |
We have used the 2.3m telescope of the Wyoming Infrared Observatory (WIRO), the 1m telescope of the United States Naval Observatory (USNO), and the 1.5m Palomar telescope to obtain B, V, and I photometry of variable stars in the Draco dwarf spheroidal galaxy. We have searched for new variables and we are constructing light and color curves in a program which will complete the inventory of Draco variables begun four decades ago by Baade & Swope. The large majority of Draco variables are RR Lyrae stars, but the system also contains a significant number of short-period ``anomalous" Cepheids. Preliminary lightcurves and the resultant period-amplitude and period-luminosity diagrams for one region of Draco are presented. When completed, this study will define the structure of the instability strip in the HR diagram from the level of the horizontal branch to a region about two magnitudes brighter. Because Draco stars exhibit a range in [Fe/H], from as metal-rich as M3 to more metal-poor than M15, the photometry will also bear upon the question of the RR Lyrae metallicity-luminosity relation, an issue important to the determination of globular cluster ages. |
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