2006/11/09 by M. Dall’Ora, M. Dall'Ora, G. Clementini +14 · 1 citation
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics and Star Formation Studies #Milky Way #Physics #Satellite #Stars #Stellar, planetary, and galactic studies #Variable star #astro-ph
paper · pdf · doi:10.1086/510665
published as Astrophys.J.653:L109-L112,2006 · Accepted for publication on ApJ Letters
arxiv created 2006/11/09 · openalex publication_date 2006/12/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present V,I light curves for 12 variable stars identified in the newly discovered satellite of the Milky Way in the Bootes constellation (Belokurov et al. 2006).Our sample includes 11 RR Lyrae stars (5 first overtone, 5 fundamental mode and 1 double mode pulsator),and one long period variable close to the galaxy red giant branch tip. The RR Lyrae stars trace very well the average V luminosity of the galaxy horizontal branch, leading to a true distance modulus for the galaxy of \μ0=19.11 \± 0.08 mag for an assumed metal abundance of [Fe/H]=-2.5 (Monoz et al. 2006), and for E(B-V)=0.02 mag. Average periods are <Pab>=0.69 d and <Pc>=0.37 d for it ab- and it c- type RR Lyrae stars, respectively, making of Bootes the second pure Oosterhoff type II (OoII) dSph after Ursa Minor. The location of the double mode RR Lyrae (RRd) in the Petersen diagram is consistent with RRd stars in OoII clusters, and corresponds to an intrinsic luminosity of log L/logL odot=1.72 (for Z=10-4 and M=0.80 M odot) according to Bono et al. (1996) pulsation models.