First HARPSpol discoveries of magnetic fields in massive stars

TL;DR

This paper reports the first detections of magnetic fields in massive stars using HARPSpol, expanding knowledge of stellar magnetism and its role in stellar evolution.

Contribution

It presents new magnetic field discoveries in three massive stars, including two He-weak stars, using high-resolution spectropolarimetry, advancing understanding of magnetic field origins in massive stars.

Findings

Discovered magnetic fields in HD 130807 and HD 122451.

Confirmed magnetic field in HD 105382 previously observed with lower resolution.

Measured strong variability in magnetic field strength for HD 130807.

Abstract

In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. In this Letter, we report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements are strongly varying for HD 130807 from $\sim$-100 G to $\sim$700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from $\sim$-40 to -80 G, and from $\sim$-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of the MiMeS objectives: the understanding of origin of magnetic fields in massive stars and their impacts on stellar structure and evolution.