First results from the LIFE project: discovery of two magnetic hot evolved stars

TL;DR

This paper reports initial findings from the LIFE project, detecting magnetic fields in two evolved hot stars, providing insights into magnetic field evolution from the main sequence to post-main sequence stages.

Contribution

It presents the first magnetic field detections in evolved hot stars, advancing understanding of magnetic evolution in massive stars.

Findings

Magnetic fields detected in two evolved hot stars.

Weak magnetic field of 1.0 G in a post-MS star.

Stronger magnetic field of 230 G in a MS/post-MS star.

Abstract

We present the initial results of the Large Impact of magnetic Fields on the Evolution of hot stars (LIFE) project. The focus of this project is the search for magnetic fields in evolved OBA giants and supergiants with visual magnitudes between 4 and 8, with the aim to investigate how the magnetic fields observed in upper main sequence (MS) stars evolve from the MS until the late post-MS stages. In this paper, we present spectropolarimetric observations of 15 stars observed using the ESPaDOnS instrument of the CFHT. For each star, we have determined the fundamental parameters and have used stellar evolution models to calculate their mass, age and radius. Using the LSD technique, we have produced averaged line profiles for each star. From these profiles, we have measured the longitudinal magnetic field strength and have calculated the detection probability. We report the detection of magnetic fields in two stars of our sample: a weak field of $B_l=1.0\pm0.2\,$G is detected in the post-MS A5 star 19$\,$Aur and a stronger field of $B_l=-230\,\pm\,10\,$G is detected in the MS/post-MS B8/9 star HR$\,$3042.