Year: 2009
Type: article
Abstract: We report on low-resolution ( R ≈ 3000) spectropolarimetry of the A0 supergiant star HD 92207. This star is well known for significant spectral variability. The source was observed on seven different nights spanning approximately three months in time. With a rotation period of approximately one year, our data cover approximately a quarter of the star's rotational phase. Variability in the continuum polarization level is observed over this period of time. The polarization across the Hα line on any given night is typically different from the degree and position angle of the polarization in the continuum. Interestingly, Hβ is not in emission and does not show polarimetric variability. We associate the changes at Hα as arising in the wind, which is in accordance with the observed changes in the profile shape and equivalent width of Hα along with the polarimetric variability. For the continuum polarization, we explore a spiral shaped wind density enhancement in the equatorial plane of the star, in keeping with the suggestion of Kaufer et al. Variable polarization signatures across Hα are too complex to be explained by this simple model and will require a more intensive polarimetric follow-up study to interpret properly.
Source: The Astronomical Journal
Authors: R. Ignace, S. Hubrig, M. Schöller
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: National Science Foundation
OpenAlex ID: W2056793934