Galactic fundamental mode RR Lyrae stars. Period - amplitude diagram, metallicities and distribution - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




Galactic fundamental mode RR Lyrae stars. Period - amplitude diagram, metallicities and distribution - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We have analysed 1455 fundamental mode RR Lyrae stars of the Galactic field,using the All Sky Automated Survey ASAS data. The sample covers 75% of thesky and contains objects in the close neighbourhood of the Sun, within 4 kpcdistance. Unlike in the previous analysis of the close field RRab, we see aclear manifestation of the Oosterhoff groups on the period - amplitude diagram.The relation for Oosterhoff I type variables becomes strongly flattened atlarge V amplitudes, which was not observed for globular cluster RR Lyrae. Wecalculate photometric metallicities using two available methods: one of Jurcsikand Kovacs 1996 and the other of Sandage 2004. We find significantdiscrepancies between results from both methods. Comparison with spectroscopicmetallicities undoubtedly favors the method of Jurcsik and Kovacs 1996. Inaddition, we notice that RRab of Oosterhoff II type might follow a differentmetallicity-period-phase relation than Oosterhoff I type variables. The spatialdistribution of Galactic field RRab does not show any metallicity gradientswith distance from the Galactic Center in either of the Oosterhoff groups.However, both the older, metal poor Oosterhoff II variables and the metal richOosterhoff I RRab become more concentrated to the Galactic plane withincreasing metal content.



Author: D. M. Szczygiel, G. Pojmanski, B. Pilecki Warsaw University Observatory

Source: https://arxiv.org/







Related documents