R-modes of a neutron star with a magnetic dipole field

Umin Lee

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


We study r-modes of a rotating magnetized neutron star, assuming a magnetic dipole field i whose axis is aligned with the axis of rotation. We approach the problem by applying a singular perturbation theory to the oscillations of rotating stars. In this treatment, we divide the star into a thin surface magnetic layer and a non-magnetic core. We integrate linearized ideal magnetohydrodynamic (MHD) equations in the surface magnetic layer and non-magnetic oscillation equations in the core, and match the two integrations at the interface to obtain a complete solution. For a polytropic neutron star model of mass M = 1.4 M* and radius R = 106 cm, the magnetic dipole field becomes effective on the modal properties of the r-modes only when the field strength Bs is much greater than 1014 G. We also find that the damping effects caused by very short magnetic perturbations in the surface layer are not important for the r-mode instability of rapidly rotating neutron stars if the field strength Bs is smaller than 1012 G.

Original languageEnglish
Pages (from-to)97-108
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 2005 Feb 11
Externally publishedYes


  • Instabilities
  • Stars: Magnetic fields
  • Stars: Neutron
  • Stars: Oscillations
  • Stars: Rotation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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