A new sample of massive B-type contact binary candidates from the OGLE survey of the Magellanic Clouds

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Main Authors: Menon, Athira, Pawlak, Michal, Lennon, Daniel J., Sen, Koushik, Langer, Norbert
Format: Preprint
Published: 2024
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author Menon, Athira
Pawlak, Michal
Lennon, Daniel J.
Sen, Koushik
Langer, Norbert
author_facet Menon, Athira
Pawlak, Michal
Lennon, Daniel J.
Sen, Koushik
Langer, Norbert
contents Massive contact binaries (CBs) are key to understanding close-binary evolution and stellar mergers, yet their study has been limited by the scarcity of observed systems, particularly of B-type binaries expected to dominate this class. We bridge this gap by mining a large sample of massive CB candidates from the OGLE-IV database, increasing their known numbers in the Magellanic Clouds by nearly an order of magnitude. Using main-sequence colour-magnitude limits, an observationally informed period-luminosity-colour relation for CBs, and a high morph-parameter cut ($c\geq0.7$), we identified 68 O- and B-type binaries that exhibit smooth, sinusoidal light curves with nearly equal eclipse depths. We then isolated a bona fide sample of 37 CB candidates (28 in the LMC and 9 in the SMC) that match theoretical colour-magnitude and period distributions derived from an extensive grid of MESA binary models. The bona fide sample, dominated by B-type systems with $P\approx0.6-1$ d, agrees with the predicted population and may contain many $q\approx1$ binaries, as expected from models showing mass equalization preceding temperature equalization during nuclear-timescale contact. Synthetic PHOEBE light curves of contact and near-contact phases of MESA models reveal a degeneracy between these configurations, suggesting possible misidentifications among these systems. Spectroscopic follow-up is required to test these predictions and refine the evolutionary framework of massive CBs.
format Preprint
id arxiv_https___arxiv_org_abs_2410_16427
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A new sample of massive B-type contact binary candidates from the OGLE survey of the Magellanic Clouds
Menon, Athira
Pawlak, Michal
Lennon, Daniel J.
Sen, Koushik
Langer, Norbert
Solar and Stellar Astrophysics
Astrophysics of Galaxies
Massive contact binaries (CBs) are key to understanding close-binary evolution and stellar mergers, yet their study has been limited by the scarcity of observed systems, particularly of B-type binaries expected to dominate this class. We bridge this gap by mining a large sample of massive CB candidates from the OGLE-IV database, increasing their known numbers in the Magellanic Clouds by nearly an order of magnitude. Using main-sequence colour-magnitude limits, an observationally informed period-luminosity-colour relation for CBs, and a high morph-parameter cut ($c\geq0.7$), we identified 68 O- and B-type binaries that exhibit smooth, sinusoidal light curves with nearly equal eclipse depths. We then isolated a bona fide sample of 37 CB candidates (28 in the LMC and 9 in the SMC) that match theoretical colour-magnitude and period distributions derived from an extensive grid of MESA binary models. The bona fide sample, dominated by B-type systems with $P\approx0.6-1$ d, agrees with the predicted population and may contain many $q\approx1$ binaries, as expected from models showing mass equalization preceding temperature equalization during nuclear-timescale contact. Synthetic PHOEBE light curves of contact and near-contact phases of MESA models reveal a degeneracy between these configurations, suggesting possible misidentifications among these systems. Spectroscopic follow-up is required to test these predictions and refine the evolutionary framework of massive CBs.
title A new sample of massive B-type contact binary candidates from the OGLE survey of the Magellanic Clouds
topic Solar and Stellar Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2410.16427