Characterizing the magnetic fields of the first tau Sco analogues

TL;DR

This paper investigates the magnetic properties of two tau Sco analogues, HD 66665 and HD 63425, revealing similar magnetic field strengths and exploring their magnetic geometry and wind characteristics through spectropolarimetric observations.

Contribution

It provides the first detailed magnetic characterization of these tau Sco analogues, linking magnetic fields to wind peculiarities in massive stars.

Findings

Both stars have similar surface magnetic field strengths.

Magnetic fields are correlated with wind peculiarities.

Phase-resolved observations reveal magnetic geometry details.

Abstract

The B0.2 V magnetic star tau Sco stands out from the larger population of massive OB stars due to its high X-ray activity, peculiar wind diagnostics and complex magnetic field. Recently, Petit et al. 2011 presented the discovery of the first two tau Sco analogues -- HD 66665 and HD 63425, identified by the striking similarity of their UV spectra to that of tau Sco. ESPaDOnS and Narval spectropolarimetric observations were obtained by the Magnetism in Massive Stars CFHT and TBL Large Programs, in order to characterize the stellar and magnetic properties of these stars. A magnetic field of similar surface strength was found on both stars, reinforcing the connection between the presence of a magnetic field and wind peculiarities. We present additional phase-resolved observations secured by the MiMeS collaboration for HD 66665 in order to measure its magnetic geometry, and correlate that geometry with diagnostics of mass-loss.