期刊
ASTRONOMY & ASTROPHYSICS
卷 428, 期 1, 页码 199-204出版社
E D P SCIENCES
DOI: 10.1051/0004-6361:20041315
关键词
stars : rotation; stars : early-type; line : profiles; stars : individual : Altair
We present a detailed spectroscopic study of line broadening in the A7IV-V star Altair. In a wavelength region covering 690 Angstrom 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 = 68degrees and it rotates at v < 245 km s(-1) or slower than 53% of breakup velocity on a 1σ level.
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