Period-Luminosity Relations for Ellipsoidal Binary Stars in the OGLE-III Fields of the Large Magellanic Cloud

M. Pawlak; I. Soszynski; P. Pietrukowicz; J. Skowron; R. Poleski; A. Udalski; M. K. Szymanski; M. Kubiak; G. Pietrzynski; L. Wyrzykowski; K. Ulaczyk; S. Kozlowski; D. M. Skowron

arXiv · 1412.2506

Period-Luminosity Relations for Ellipsoidal Binary Stars in the OGLE-III Fields of the Large Magellanic Cloud

M. Pawlak·I. Soszynski·P. Pietrukowicz·J. Skowron·R. Poleski·A. Udalski·M. K. Szymanski·M. Kubiak·G. Pietrzynski·L. Wyrzykowski·K. Ulaczyk·S. Kozlowski·D. M. Skowron

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Abstract

We report the discovery of two distinct types of ellipsoidal binary systems occupying, so called, sequence E on the period-luminosity (P-L) diagram. We propose that steeper P-L relation is composed of giant-dwarf binaries, while the other consists of giant-giant binary systems. Analysis is based on a sample of 5334 objects, which we select from the OGLE-III survey data toward the the Large Magellanic Cloud. We show that one of the components of ellipsoidal binaries is typically either a Red Clump or a Red Giant Branch star, which leads to clear separation split of the sequence E at P = 40 d. In its short-period part, we identify two subsequences corresponding to the two types of binary systems (E2 and E3), while in the longer-period part the two groups merge forming a single subsequence E1. We extract a group of 271 ellipsoidal systems with eccentric orbits, from our sample. We present the period-luminosity relation they follow.

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M. Pawlak, I. Soszynski, P. Pietrukowicz, J. Skowron, R. Poleski, A. Udalski, M. K. Szymanski, M. Kubiak, G. Pietrzynski, L. Wyrzykowski, K. Ulaczyk, S. Kozlowski, D. M. Skowron. 2014-12-08. Period-Luminosity Relations for Ellipsoidal Binary Stars in the OGLE-III Fields of the Large Magellanic Cloud. https://arxiv.org/abs/1412.2506

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