Angular momentum loss and stellar spin-down in magnetic massive stars

Asif Ud-Doula, Stanley P. Owocki, Richard H.D. Townsend

Research output: Contribution to journalArticlepeer-review


We examine the angular momentum loss and associated rotational spin-down for magnetic hot stars with a line-driven stellar wind and a rotation-Aligned dipole magnetic field. Our analysis here is based on our previous 2-D numerical MHD simulation study that examines the interplay among wind, field, and rotation as a function of two dimensionless parameters, W(=Vrot/Vorb) and 'wind magnetic confinement', ηâ-defined below. We compare and contrast the 2-D, time variable angular momentum loss of this dipole model of a hot-star wind with the classical 1-D steady-state analysis by Weber and Davis (WD), who used an idealized monopole field to model the angular momentum loss in the solar wind. Despite the differences, we find that the total angular momentum loss averaged over both solid angle and time follows closely the general WD scaling ΩR2A. The key distinction is that for a dipole field Alfvèn radius RA is significantly smaller than for the monopole field WD used in their analyses. This leads to a slower stellar spin-down for the dipole field with typical spin-down times of order 1 Myr for several known magnetic massive stars.

Original languageEnglish (US)
Pages (from-to)423-424
Number of pages2
JournalProceedings of the International Astronomical Union
StatePublished - Nov 1 2008

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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