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arXiv · 2505.12852

A magnetic tertiary in the most massive compact triple-star system

S. Hubrig·A. Vigna-Gómez·S. P. Järvinen·M. Schöller·I. Ilyin
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Abstract

The system TIC 470710327 is comprised of three main-sequence OB stars, with an inner compact 1.10 d eclipsing binary and a non-eclipsing tertiary on a 52.04 d orbit. With the tertiary mass of 14.5-16 $M_{\odot}$ and both components in the inner eclipsing binary with individual masses of 6--7 and 5.5-6.3 $M_{\odot}$, it is currently the most massive compact system known. The formation scenario of such a compact triple is uncertain. It has been suggested that `2 + 2' quadruple dynamics can lead to a stellar merger in the initially more massive binary and finally result in a highly magnetised tertiary. Our study confirms the presence of a kG-order magnetic field in the tertiary and the slow rotation typical for massive magnetic stars. We conclude that finding massive merger candidates by studies of dynamics in compact, multiple-star systems is an efficient way to understand the evolution of massive stellar multiplicity and the generation of magnetic fields.

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S. Hubrig, A. Vigna-Gómez, S. P. Järvinen, M. Schöller, I. Ilyin. 2025-05-19. A magnetic tertiary in the most massive compact triple-star system. https://arxiv.org/abs/2505.12852

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