tau Sco: The discovery of the clones

TL;DR

This paper discusses the discovery of tau Sco analogues with similar UV spectra, their magnetic field detections, and ongoing efforts to understand their complex magnetic topology and wind structures.

Contribution

It reports the identification of tau Sco analogues and the first magnetic field detections, advancing understanding of magnetic OB stars with superionized winds.

Findings

Detection of magnetic fields in tau Sco analogues

Confirmation of the link between magnetic fields and superionized winds

Ongoing efforts to map magnetic topology

Abstract

The B0.2 V magnetic star tau Sco stands out from the larger population of massive magnetic OB stars due to its remarkable, superionized wind, apparently related to its peculiar magnetic field - a field which is far more complex than the mostly-dipolar fields usually observed in magnetic OB stars. tau Sco is therefore a puzzling outlier in the larger picture of stellar magnetism - a star that still defies interpretation in terms of a physically coherent model. Recently, two early B-type stars were discovered as tau Sco analogues, identified by the striking similarity of their UV spectra to that of tau Sco, which was - until now - unique among OB stars. We present the recent detection of their magnetic fields by the MiMeS collaboration, reinforcing the connection between the presence of a magnetic field and a superionized wind. We will also present ongoing observational efforts undertaken to establish the precise magnetic topology, in order to provide additional constrains for existing models attempting to reproduce the unique wind structure of tau Sco-like stars.