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First signatures of strong differential rotation in A-type stars
Published online by Cambridge University Press: 02 March 2005
Abstract
We reanalyzed high quality spectra of 158 stars of spectral types A0–F1 and $v\,\sin{i}$ values between 60 and 150 km s$^{-1}$. Using a least squares deconvolution technique we extracted high $S/N$ broadening profiles and determined the loci of the Fourier transform zeros $q_{1}$ and $q_{2}$ where the $S/N$-ratio was high enough. For 78 stars $q_{2}$ could be determined and the ratio $q_{2}/q_{1}$ was used as a shape parameter sensitive to solar-like differential rotation (the equatorial velocity is faster than the near polar velocities). Seventy-four of the 78 stars have values of $q_{2}/q_{1}$ consistent with solid body rotation; in four of the 78 cases, values of $q_{2}/q_{1}$ are not consistent with rigid rotation. Although these stars may be binaries, none of their profiles shows any signatures of a companion. The Fourier transforms do not indicate any distortions and the broadening profiles can be considered due to single objects. One of these candidates may be an extremely rapid rotator seen pole-on, but for the other three stars of spectral types as early as A6, differential rotation seems to be the most plausible explanation for the peculiar profiles.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html
Keywords
- Type
- Contributed Papers
- Information
- Proceedings of the International Astronomical Union , Volume 2004 , Issue IAUS224 , July 2004 , pp. 95 - 101
- Copyright
- © 2004 International Astronomical Union