Weak magnetic fields of intermediate-mass stars

TL;DR

This study detects sub-gauss magnetic fields on intermediate-mass stars Vega and Sirius A, indicating that many such stars may host magnetized photospheres, challenging previous notions about stellar magnetism.

Contribution

First detection of weak magnetic fields on normal, rapidly-rotating A-type and Am stars, expanding understanding of stellar magnetism beyond classical magnetic star classes.

Findings

Detected sub-gauss magnetic fields on Vega and Sirius A

Evidence that non-Ap/Bp stars can host magnetized photospheres

Suggests a significant fraction of intermediate-mass stars are magnetic

Abstract

We present the result of a highly sensitive spectropolarimetric study dedicated to intermediate mass stars. We report the detection of sub-gauss surface magnetic fields on the normal, rapidly-rotating A-type star Vega and on the moderately-rotating Am star Sirius A. These magnetic detections constitute the first evidence that tepid stars that do not belong to the class of Ap/Bp stars can also host magnetized photospheres, suggesting that a significant fraction of stars in this mass regime are magnetic. We present here the observational clues gathered so far to progress towards understanding the physical processes at the origin of this newly identified Vega-like magnetism.