2011/03/09 by David A. Bohlender, Dmitry Monin · 30 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Magnetic dipole #Magnetic field #Magnetosphere #Polar #Rotation (mathematics) #Rotation period #Stars #Stellar rotation #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.1088/0004-6256/141/5/169
published in The Astronomical Journal 141(5), 169 (Institute of Physics) · 16 pages, 6 figures
arxiv created 2011/03/09 · openalex publication_date 2011/04/07 · arxiv updated 2015/05/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the detection of a strong, reversing magnetic field and variable Hα emission in the bright helium-weak star HD 176582 (HR 7185). Spectrum, magnetic, and photometric variability of the star are all consistent with a precisely determined period of 1.5819840 ± 0.0000030 days which we assume to be the rotation period of the star. From the magnetic field curve, and assuming a simple dipolar field geometry, we derive a polar field strength of approximately 7 kG and a lower limit of 52° for the inclination of the rotation axis. However, based on the behavior of the Hα emission, we adopt a large inclination angle of 85° and this leads to a large magnetic obliquity of 77°. The Hα emission arises from two distinct regions located at the intersections of the magnetic and rotation equators and which corotate with the star at a distance of about 3.5 R * above its surface. We estimate that the emitting regions have radial and meridional sizes on the order of 2 R * and azimuthal extents (perpendicular to the magnetic equator) of less than approximately 0.6 R * . HD 176582 therefore appears to show many of the cool magnetospheric phenomena as that displayed by other magnetic helium-weak and helium-strong stars such as the prototypical helium-strong star σ Ori E. The observations are consistent with current models of magnetically confined winds and rigidly rotating magnetospheres for magnetic Bp stars.