Altair's inclination from line profile analysis
Abstract
We present a detailed spectroscopic study of line broadening in the A7IV-V star Altair. In a wavelength region covering 690 Å we reconstruct the overall broadening profile taking into account more than 650 spectral lines. From the broadening profile we determine the projected rotational velocity v sin i, derive an upper limit for the equatorial velocity v from the shape of the profile and search for signatures of differential rotation. Our redetermined value of v sin i is (227 ± 11) km s-1. Measuring the first two zeros of the Fourier transformed broadening profile yields no signatures of differential rotation. We derive that Altair is seen under an inclination angle higher than i = 68° and it rotates at v < 245 km s-1 or slower than 53% of breakup velocity on a 1σ level.
Based on observations carried out at Observatoire de Haute-Provence (OHP), at the German-Spanish Astronomical Centre, Calar Alto, and retrieved from the Elodie Archive at Observatoire de Haute-Provence (OHP).- Publication:
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Astronomy and Astrophysics
- Pub Date:
- December 2004
- DOI:
- 10.1051/0004-6361:20041315
- arXiv:
- arXiv:astro-ph/0408194
- Bibcode:
- 2004A&A...428..199R
- Keywords:
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- stars: rotation;
- stars: early-type;
- line: profiles;
- stars: individual: Altair;
- Astrophysics
- E-Print:
- A&