A massive helium star with a sufficiently strong magnetic field to form a magnetar
T. Shenar, G. A. Wade, Pablo Marchant, S. Bagnulo, J. Bodensteiner, D. M. Bowman, Avishai Gilkis, N. Langer, André-Nicolas Chené, L. M. Oskinova, T. Van Reeth, H. Sana, Nicole St‐Louis, A. S. Oliveira, H. Todt, Silvia Toonen
Abstract
Magnetars are highly magnetized neutron stars, the formation mechanism of which is unknown. Hot helium-rich stars with spectra dominated by emission lines are known as Wolf-Rayet stars. We observed the binary system HD 45166 using spectropolarimetry and reanalyzed its orbit using archival data. We found that the system 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 supernova, and that its magnetic field is strong enough for the supernova to leave a magnetar remnant. We propose that the magnetized Wolf-Rayet star formed by the merger of two lower-mass helium stars.