The Properties of the Magellanic Bridge Based on OGLE IV RR Lyrae Variables

Abstract

We examine the properties of the Magellanic Bridge connecting the Large and Small Magellanic Clouds using ab-type RR Lyrae variables from the extensive dataset of the Optical Gravitational Lensing Experiment (OGLE), Phase IV data release. The metallicities of the RR Lyraes are determined from the characteristics of their light curves, with an average abundance of [Fe/H] = -1.790 +/- 0.011 (sem) in the Magellanic Bridge. From the individual reddenings of these stars, derived via their minimum light curve colors, we determined a median color excess of E(V-I) = 0.101 +/- 0.007 (sem) (implying E(B-V) $\approx$ 0.077). The peak distance modulus of 18.57 +/- 0.048 (sem) places the Bridge stars at distances between the two systems. The metallicity and distance distributions probe the structure of the Magellanic system as a whole, revealing a smooth transition that connects the galaxies. An examination of the HI content does not find a clear correlation between HI emission strength and RR Lyrae spatial distribution, suggesting that the old stellar populations may trace the overlapping halo distributions of the two Magellanic Clouds.

Accepted 2016 December 5. Received 2016 December 5; in original form 2016 November 7. 10 pages, 8 figures, 5 Tables

References in corpus (6)

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• Presence of red giant population in the foreground stellar sub-structure of the Small Magellanic Cloud
• OGLE-ing the Magellanic System: Cepheids in the Bridge
• Detailed Chemical Abundances of Star Clusters in the Large Magellanic Cloud
• Residual velocities of Small Magellanic Cloud star clusters
• Stellar density distribution along the minor axis of the Large Magellanic Cloud
• Revisiting a detached stellar structure in the outer northeastern region of the Small Magellanic Cloud