Strong latitudinal shear in the shallow convection zone of a rapidly rotating A-star
Abstract
We have derived the mean broadening profile of the star V 102 in the region of the open cluster IC 4665 from high resolution spectroscopy. At a projected equatorial rotation velocity of v sin i = (105 ± 12) km s-1 we find strong deviation from classical rotation. We discuss several scenarios, the most plausible being strong differential rotation in latitudinal direction. For this scenario we find a difference in angular velocity of ΔΩ = 3.6 ± 0.8 rad d-1 (ΔΩ/Ω = 0.42 ± 0.09). From the Hα line we derive a spectral type of A9 and support photometric measurements classifying IC 4665 V 102 as a non-member of IC 4665. At such early spectral type this is the strongest case of differential rotation observed so far. Together with three similar stars, IC 4665 V 102 seems to form a new class of objects that exhibit extreme latitudinal shear in a very shallow convective envelope.
Based on observations carried out at the European Southern Observatory, Paranal, 71.D-0127(A).- Publication:
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Astronomy and Astrophysics
- Pub Date:
- January 2005
- DOI:
- 10.1051/0004-6361:200400120
- arXiv:
- arXiv:astro-ph/0412225
- Bibcode:
- 2005A&A...430L..17R
- Keywords:
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- stars: rotation;
- line: profiles;
- stars: individual: IC 4665 V 102/P35;
- clusters: individual: IC 4665;
- Astrophysics
- E-Print:
- accepted for A&