EDP Sciences
Free Access
Volume 428, Number 1, December II 2004
Page(s) 199 - 204
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361:20041315

A&A 428, 199-204 (2004)
DOI: 10.1051/0004-6361:20041315

Altair's inclination from line profile analysis

A. Reiners1, 2 and F. Royer3, 4

1  Astronomy Department, University of California, Berkeley, CA 94720, USA
    e-mail: areiners@astron.berkeley.edu
2  Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
3  Observatoire de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland
    e-mail: frederic.royer@obs.unige.ch
4  GEPI, CNRS UMR 8111, Observatoire de Paris, 5 place Janssen, 92195 Meudon Cedex, France

(Received 18 May 2004 / Accepted 9 August 2004)

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 ( $227 \pm 11$) 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 $i = 68^{\circ}$ and it rotates at v < 245 km s -1 or slower than 53% of breakup velocity on a $1\sigma$ level.

Key words: stars: rotation -- stars: early-type -- line: profiles -- stars: individual: Altair

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