HD 45166 and Plaskett's star: two cases of binary evolution implicating magnetic fields

Gregg Wade

Royal Military College of Canada and Queen's University

Recent observations and modeling of massive stars lead to the inescapable conclusion that the classical theory of stellar evolution - envisioning single stars evolving in an isolated fashion - is fundamentally wrong in many, and quite possibly most, cases. A majority of massive stars are known to form in binary or higher-order multiple systems, and as these stars evolve they expand to fill their Roche Lobes, resulting in mass and angular momentum exchange. The resultant stripped star mass donors and rejuvenated mass recipients are characterized by masses, rotational properties, and surface chemistry that are entirely at odds with evolution models of single stars.

The rapid and violent evolution resulting from mass transfer and merger events also provide fertile grounds for the generation of powerful magnetic fields. This talk explores the intriguing cases of HD 45166 and Plaskett's star, both examples of binary evolution implicating magnetic fields. HD 45166, a system consisting of a main sequence B-type primary and a stripped star companion, was recently discovered to host an extraordinarily strong magnetic field (Shenar et al., Science, 2023), likely a consequence of the merger of two intermediate-mass stars. Similarly, Plaskett's star, a massive O-type binary, comprises a magnetic component and a (non-magnetic) stripped-star companion that has likely recently undergone mass transfer (Wade et al., Nature, in prep.). These case studies highlight the intricate interplay between binary interactions and magnetic fields, shedding light on the diverse evolutionary pathways of massive stars and the role of magnetic fields in shaping their observable properties.

Date:	Thursday, 25 April 2024
Time:	12:30
Where:	Université de Montréal
	Pavillon MIL, salle A-3521.1