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RR Lyrae Stars in the MACHO Database

1996/10/03 by D. Minniti, The MACHO Collaboration, Minniti, D. +40
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.48550/arxiv.astro-ph/9610025

10 pages, 8 Encapsulated PostScript figures, uses conf_iap.sty. To appear in the Proceeding of the 12th IAP Colloquium "Variable Stars and the Astrophysical Returns of Microlensing Surveys"

arxiv created 1996/10/03 · openalex publication_date 1996/10/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

The MACHO Project has catalogued ∼ 8000 RR Lyrae stars in the Large Magellanic Cloud, ∼ 1800 in the Galactic bulge, and ∼ 50 in the Sgr dwarf galaxy. These variables are excellent distance indicators, and are used as tools to study the structure of the Large Magellanic Cloud and the bulge. The large datasets also probe uncommon pulsation modes. A number of double-mode RR Lyrae stars (RRd) are found in the Large Magellanic Cloud sample. These stars provide important clues for understanding the formation and evolution of the inner Galaxy, the Large Magellanic Cloud and the Sgr dwarf galaxy. A large number of second overtone pulsators (RRe) are found in the LMC and bulge. Finally, the RR Lyrae belonging to the Sgr dwarf yield an accurate distance to this galaxy. Their presence also alerts us of the very interesting possibility of distant sources for bulge microlensing events.

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