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Paper: Variability in the Milky Way: Contact Binaries as Diagnostic Tools
Volume: 511, Non-Stable Universe: Energetic Resources, Activity Phenomena and Evolutionary Processes
Page: 23
Authors: de Grijs, R.; Chen, X.; Deng, L.
Abstract: We used the 50 cm Binocular Network (50BiN) telescope at Delingha Station (Qinghai Province) of Purple Mountain Observatory (Chinese Academy of Sciences) to obtain simultaneous V- and R-band observations of the old open cluster NGC 188. Our aim was a search for populations of variable stars. We derived light-curve solutions for six W Ursae Majoris (W UMa) eclipsing-binary systems and estimated their orbital parameters. The resulting distance to the W UMas is independent of the physical characteristics of the host cluster. We next determined the current best period–luminosity relations for contact binaries (CBs; scatter σ<0.10 mag). We conclude that CBs can be used as distance tracers with better than 5% uncertainty. We apply our new relations to the 102 CBs in the Large Magellanic Cloud, which yields a distance modulus of (m–M)V,0=18.41±0.20 mag.
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