Volume 559, November 2013
|Number of page(s)||8|
|Section||Stellar structure and evolution|
|Published online||30 October 2013|
The fundamental parameters of the roAp star 10 Aquilae⋆
Institut d’Astrophysique et de Planétologie de Grenoble, CNRS-UJF UMR
414 rue de la Piscine, 38400
St Martin d’Hères
2 Centro de Astrofísica e Faculdade de Ciências, Universidade do Porto, 4150-762 Porto, Portugal
3 Laboratoire Lagrange, UMR 7293 UNS-CNRS-OCA, Boulevard de l’Observatoire, BP 4229, 06304 Nice Cedex 4, France
4 Georgia State University, PO Box 3969, Atlanta GA 30302-3969, USA
5 CHARA Array, Mount Wilson Observatory, 91023 Mount Wilson CA, USA
Received: 6 May 2013
Accepted: 9 August 2013
Context. Owing to the strong magnetic field and related abnormal surface layers existing in rapidly oscillating Ap (roAp) stars, systematic errors are likely to be present when determining their effective temperatures, which potentially compromises asteroseismic studies of this class of pulsators.
Aims. Using the unique angular resolution provided by long-baseline visible interferometry, our goal is to determine accurate angular diameters of a number of roAp targets, so as to derive unbiased effective temperatures (Teff) and provide a Teff calibration for these stars.
Methods. We obtained long-baseline interferometric observations of 10 Aql with the visible spectrograph VEGA at the combined focus of the CHARA array. We derived the limb-darkened diameter of this roAp star from our visibility measurements. Based on photometric and spectroscopic data available in the literature, we estimated the star’s bolometric flux and used it, in combination with its parallax and angular diameter, to determine the star’s luminosity and effective temperature.
Results. We determined a limb-darkened angular diameter of 0.275 ± 0.009 mas and deduced a linear radius of R = 2.32 ± 0.09 R⊙. For the bolometric flux we considered two datasets, leading to an effective temperature of Teff = 7800 ± 170 K and a luminosity of L/L⊙ = 18 ± 1 or Teff = 8000 ± 210 K and L/L⊙ = 19 ± 2. Finally we used these fundamental parameters together with the large frequency separation determined by asteroseismic observations to constrain the mass and the age of 10 Aql, using the CESAM stellar evolution code. Assuming a solar chemical composition and ignoring all kinds of diffusion and settling of elements, we obtained a mass M/M⊙ ~ 1.92 and an age of ~780 Gy or a mass M/M⊙ ~ 1.95 and an age of ~740 Gy, depending on the derived value of the bolometric flux.
Conclusions. For the first time, thanks to the unique capabilities of VEGA, we managed to determine an accurate angular diameter for a star smaller than 0.3 mas and to derive its fundamental parameters. In particular, by only combining our interferometric data and the bolometric flux, we derived an effective temperature that can be compared to those derived from atmosphere models. Such fundamental parameters can help for testing the mechanism responsible for the excitation of the oscillations observed in the magnetic pulsating stars.
Key words: methods: observational / techniques: high angular resolution / techniques: interferometric / stars: individual: 10 Aql / stars: fundamental parameters
© ESO, 2013
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.