On the origin of magnetic fields in stars

J. Wurster, Matthew R. Bate, Daniel J. Price

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

Are the kG-strength magnetic fields observed in young stars a fossil field left over from their formation or are they generated by a dynamo? We use radiation non-ideal magnetohydrodynamics simulations of the gravitational collapse of a rotating, magnetized molecular cloud core over 17 orders of magnitude in density, past the first hydrostatic core to the formation of the second, stellar core, to examine the fossil field hypothesis. Whereas in previous work, we found that magnetic fields in excess of 10 kG can be implanted in stars at birth, this assumed ideal magnetohydrodynamics (MHD), i.e. that the gas is coupled to the magnetic field. Here we present non-ideal MHD calculations which include Ohmic resistivity, ambipolar diffusion, and the Hall effect. For realistic cosmic ray ionization rates, we find that magnetic field strengths of ≲ kG are implanted in the stellar core at birth, ruling out a strong fossil field. While these results remain sensitive to resolution, they cautiously provide evidence against a fossil field origin for stellar magnetic fields, suggesting instead that magnetic fields in stars originate in a dynamo process.
Original languageEnglish
Pages (from-to)2450-2457
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume481
Issue number2
Early online date5 Sept 2018
DOIs
Publication statusPublished - Dec 2018

Keywords

  • Magnetic fields
  • MHD
  • Methods: numerical
  • Stars: formation

Fingerprint

Dive into the research topics of 'On the origin of magnetic fields in stars'. Together they form a unique fingerprint.

Cite this