2009/03/02 by Cecilia Mateu, A. K. Vivas, A. Katherina Vivas +5 · 2 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1088/0004-6256/137/5/4412
35 pages, 9 figures, 5 tables. Accepted for publication at the Astronomical Journal
arxiv created 2009/03/02 · openalex publication_date 2009/04/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Our multi-epoch survey of ∼20 deg 2 of the Canis Major (CMa) overdensity has detected only 10 RR Lyrae stars (RRLS). We show that this number is consistent with the number expected from the Galactic halo and thick disk populations alone, leaving no excess that can be attributed to the dwarf spheroidal (dSph) galaxy that some authors have proposed as the origin of the CMa overdensity. If this galaxy resembles the dSph satellites of the Milky Way (MW) and of M31 and has the putative M V ∼ −14.5, our survey should have detected several tens of RRLS. Even if M V ≲ −12, the expected excess is ≳10, which is not observed. Either the old stellar population of this galaxy has unique properties or, as others have argued before, the CMa overdensity is produced by the thin and thick disk and spiral arm populations of the MW and not by a collision with a dSph satellite galaxy.