EDP Sciences
Free Access
Volume 442, Number 2, November I 2005
Page(s) 567 - 578
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361:20042476
Published online 07 October 2005

A&A 442, 567-578 (2005)
DOI: 10.1051/0004-6361:20042476

Gravitational-darkening of Altair from interferometry

A. Domiciano de Souza1, P. Kervella2, S. Jankov3, 4, F. Vakili3, N. Ohishi5, T. E. Nordgren6 and L. Abe5

1  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
    e-mail: adomicia@mpifr-bonn.mpg.de
2  LESIA, UMR 8109, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France
3  Lab. Univ. d'Astrophysique de Nice (LUAN), UMR 6525, UNSA, Parc Valrose, 06108 Nice Cedex 02, France
4  Astronomical Observatory Belgrade, MNTRS 1940, Volgina 7, 11050 Beograd, Serbia and Montenegro
5  National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
6  Department of Physics, University of Redlands, 1200 East Colton Avenue, Redlands, CA 92373, USA

(Received 3 December 2004 / Accepted 13 June 2005)

Interferometric observations have revealed that the rapid rotator Altair is a flattened star with a non-centrally symmetric intensity distribution. In this work we perform for the first time a physically consistent analysis of all interferometric data available so far, corresponding to three different interferometers operating in several spectral bands. These observations include new data (squared visibilities in the H and K bands from VLTI-VINCI) as well as previously published data (squared visibilities in the K band from PTI and squared visibilities, triple amplitudes, and closure phases in the visible between 520 nm and 850 nm from NPOI). To analyze these data we perform a $\chi^2$ minimization using an interferometry-oriented model for fast rotators, which includes Roche approximation, limb-darkening, and von Zeipel-like gravity-darkening. Thanks to the rich interferometric data set available and to this physical model, the main uniqueness problems were avoided. As a result, we show that the observations can only be explained if Altair has a gravity-darkening compatible with the expected value for hot stars, i.e., the von Zeipel effect ( $T_\mathrm{eff}\propto

Key words: techniques: high angular resolution -- techniques: interferometric -- methods: data analysis -- stars: rotation -- stars: individual: Altair

SIMBAD Objects

© ESO 2005

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.