2010/04/13 by R. H. D. Townsend, M. E. Oksala, David H. Cohen +4 · 2 citations
Physics and Astronomy · #Angular momentum #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Classical mechanics #Helium #Observatory #Photometry (optics) #Physics #Rotation period #Stars #Stellar rotation #Stellar, planetary, and galactic studies #Telescope #astro-ph.SR
paper · pdf · doi:10.1088/2041-8205/714/2/l318
6 pages, 3 figures, accepted by ApJ Letters, typos corrected
arxiv created 2010/04/13 · openalex publication_date 2010/04/26 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present new U -band photometry of the magnetic helium-strong star σ Ori E, obtained over 2004–2009 using the SMARTS 0.9 m telescope at Cerro Tololo Inter-American Observatory. When combined with historical measurements, these data constrain the evolution of the star's 1.19 day rotation period over the past three decades. We are able to rule out a constant period at the p null = 0.05% level, and instead find that the data are well described ( p null = 99.3%) by a period increasing linearly at a rate of 77 ms per year. This corresponds to a characteristic spin-down time of 1.34 Myr, in good agreement with theoretical predictions based on magnetohydrodynamical simulations of angular momentum loss from magnetic massive stars. We therefore conclude that the observations are consistent with σ Ori E undergoing rotational braking due to its magnetized line-driven wind.