A massive helium star with a sufficiently strong magnetic field to form a magnetar

TL;DR

This paper presents evidence that a massive, magnetized Wolf-Rayet star in a binary system could be the progenitor of a magnetar, providing insights into magnetar formation mechanisms.

Contribution

It reports the discovery of a magnetized Wolf-Rayet star with a strong magnetic field, suggesting a new pathway for magnetar formation through stellar mergers.

Findings

The Wolf-Rayet star has a magnetic field of 43 kilogauss.

Stellar evolution models predict it will become a magnetar.

The star likely formed from a merger of two helium stars.

Abstract

Magnetars are highly magnetized neutron stars; their formation mechanism is unknown. Hot helium-rich stars with spectra dominated by emission lines are known as Wolf-Rayet stars. We observe the binary system HD 45166 using spectropolarimetry, finding that it contains a Wolf-Rayet star with a mass of 2 solar masses and a magnetic field of 43 kilogauss. Stellar evolution calculations indicate that this component will explode as a type Ib or IIb supernova, and the strong magnetic field favors a magnetar remnant. We propose that the magnatized Wolf-Rayet star formed by the merger of two lower mass helium stars.