Survival of fossil magnetic fields into the main sequence in massive stars

Establish whether large-scale magnetic fields inherited from star-forming material and sustained by pre-main-sequence convection in massive stars can survive once these stars reach the main sequence.

Background

The paper reviews proposed origins of magnetism in massive stars, including fossil fields retained from the birth environment and fields produced during stellar interactions or mergers. While lower-mass stars sustain dynamos in convective envelopes, massive stars have radiative envelopes on the main sequence, raising doubts about the longevity of any pre-main-sequence magnetic fields.

The authors explicitly note that it is unclear whether fossil or pre-main-sequence dynamo-generated fields can persist into the main-sequence phase of massive stars. Their observational results support mergers as a viable magnetic-field origin, but the survival of fossil fields remains an unresolved question.

References

However, it is unclear whether such fields would survive once the stars reach the main sequence.

— A magnetic massive star has experienced a stellar merger  (2404.10167 - Frost et al., 2024) in Main text, paragraph discussing proposed magnetic field origins, preceding the subsubsection "The HD 148937 system"

It is highly uncertain whether a large enough number of progenitors can have such strong magnetic fields .

— Large ${\rm Pm}$ small-scale kinematic dynamo in protoneutron stars  (2609.17365 - Verma et al., 15 Sep 2026) in Section 1, Introduction

Moreover, it is unclear if the fossil field is left undisturbed when subjected to the strong turbulent convective motions in PNS.

— Large ${\rm Pm}$ small-scale kinematic dynamo in protoneutron stars  (2609.17365 - Verma et al., 15 Sep 2026) in Section 1, Introduction