Discovery of a strong magnetic field in the rapidly rotating B2Vn star HR 7355

TL;DR

This paper reports the discovery of a strong, organized magnetic field in the rapidly rotating B2Vn star HR 7355, supported by spectropolarimetric and photometric data, indicating a structured magnetosphere similar to sigma Ori E.

Contribution

First detection of a strong magnetic field in HR 7355 using spectropolarimetry, revealing a structured magnetosphere in a rapidly rotating B-type star.

Findings

Detection of a strong magnetic field in HR 7355.

Evidence of a structured magnetosphere similar to sigma Ori E.

Confirmation of the star's rapid rotation and magnetic properties.

Abstract

We report on the detection of a strong, organized magnetic field in the helium-variable early B-type star HR 7355 using spectropolarimetric data obtained with ESPaDOnS on CFHT by the MiMeS large program. We also present results from new V-band differential photometry obtained with the CTIO 0.9m telescope. We investigate the longitudinal field, using a technique called Least-Squares Deconvolution (LSD), and the rotational period of HR 7355. These new observations strongly support the proposal that HR 7355 harbors a structured magnetosphere similar to that in the prototypical helium-strong star, sigma Ori E.