Cluster AgeS Experiment (CASE): RR Lyrae stars from the globular cluster ω Centauri as standard candles |
| |
| Authors: | A Olech J Kaluzny I B Thompson A Schwarzenberg-Czerny |
| |
| Institution: | Nicolaus Copernicus Astronomical Centre, ul. Bartycka 18, 00-716 Warsaw, Poland;Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101, USA;Adam Mickiewicz University Observatory, ul. Sloneczna 36, 60-286 Poznan, Poland |
| |
| Abstract: | New photometry of RRab and RRc stars in ω Centauri is used to calibrate their absolute magnitudes MV as a function of (a) metallicity and (b) the Fourier parameters of light curves in the V band. The zero point of both calibrations relies on the distance modulus to the cluster derived earlier by the Cluster AgeS Experiment (CASE) project based on observations of the detached eclipsing binary OGLE GC17. For RRab variables, we obtained a relation of MV = (0.26 ± 0.08) Fe/H ] + (0.91 ± 0.13) . A dereddened distance modulus to the Large Magellanic Cloud (LMC) based on that formula is μ0= 18.56 ± 0.14 mag . The second calibration of MV , which is based on Fourier coefficients of decomposed light curves, results in the LMC distance of μ0= 18.51 ± 0.07 mag . |
| |
| Keywords: | stars: variables: other globular clusters: individual: ω Centauri |
|
|
