The Structure of the Large Magellanic Halo Stellar Halo Derived Using OGLE-III RR Lyr stars

Abstract

We use the recently released OGLE-III catalog of 17692 fundamental mode RR Lyr (RRab) stars in the Large Magellanic Cloud (LMC) to investigate the structure of its stellar halo. We apply conservative cuts in period, amplitude and magnitude to remove blends and other contamination. We use period--luminosity and period--color relations to determine distance and extinction of every star in our final sample of 9393 stars. In order to determine the scatter of our method, we compare the distributions of distances in two regions at the edges of the covered area with a central region. We determine the intrinsic line-of-sight dispersion in the center to be 0.135 mag or 3.21 kpc (FWHM of 0.318 mag or 7.56 kpc), assuming zero depth in one of the edge regions. The conservative cuts we apply reduce the derived depth significantly. Furthermore, we find that the distribution of RRab stars is deformed in the sense that stars on the Eastern side are closer than on the Western side. We model the RRab distribution as a triaxial ellipsoid and determine its axes ratios to be 1:2.00:3.50 with the longest axis inclined by 6 degrees from the line of sight. Another result of our analysis is an extinction map of the LMC and a map of internal reddening, which we make publicly available.

Accepted for publication in November 2009 issue of ApJ. 7 pages, 5 figures. Extinction map of the LMC available at http://www.astronomy.ohio-state.edu/~pejcha/lmc_extmap

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• The VMC survey - XXVI. Structure of the Small Magellanic Cloud from RR Lyrae stars
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• Three dimensional maps of the Magellanic Clouds using RR~Lyrae stars and Cepheids - I. The Large Magellanic Cloud
• The Origin of the Microlensing Events Observed Towards the LMC and the Stellar Counterpart of the Magellanic Stream
• Empirical calibration of the reddening maps in the Magellanic Clouds
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• The ASAS-SN Catalog of Variable Stars IV: Periodic Variables in the APOGEE Survey
• Microlensing towards the LMC: self lensing for OGLE-II and OGLE-III
• The Distance to the Massive Eclipsing Binary LMC-SC1-105 in the Large Magellanic Cloud
• Morphology and metallicity of the Small Magellanic Cloud using RRab stars
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• The Properties of the Large Magellanic Cloud Based on OGLE III Photometry of RR Lyrae Stars
• Modeling Transiting Circumstellar Disks: Characterizing the Newly Discovered Eclipsing Disk System OGLE LMC-ECL-11893
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