Volume 559, November 2013
|Number of page(s)||14|
|Section||Stellar structure and evolution|
|Published online||15 November 2013|
An in-depth study of HD 174966 with CoRoT photometry and HARPS spectroscopy
Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762
2 Instituto de Astrofísica de Andalucía (CSIC), CP3004, Granada, Spain
3 Departamento de Astrofísica, Centro de Astrobiología (INTA-CSIC), PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
4 LESIA, Observatoire de Paris, CNRS UMR 8109, Université Pierre et Marie Curie, Université Denis Diderot, 5 place J. Janssen, 92195 Meudon, France
5 INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
6 Instituto de Astrofísica de Canarias, 38200, La Laguna, Tenerife, Spain
7 Departamento de Astrofísica, Universidad de La Laguna, 38205, La Laguna, Tenerife, Spain
8 Spanish Virtual Observatory, 28691 Villanueva de la Cañada, Madrid, Spain
9 Université de Toulouse, UPS-OMP, IRAP, Tarbes, France
10 CNRS, IRAP, 57 avenue d’Azereix, 65000 Tarbes, France
11 Institut d’Astrophysique Spatiale, CNRS/Université Paris XI UMR 8617, 91405 Orsay, France
Received: 19 August 2012
Accepted: 5 July 2013
Aims. The aim of this work was to use a multi-approach technique to derive the most accurate values possible of the physical parameters of the δ Sct star HD 174966, which was observed with the CoRoT satellite. In addition, we searched for a periodic pattern in the frequency spectra with the goal of using it to determine the mean density of the star.
Methods. First, we extracted the frequency content from the CoRoT light curve. Then, we derived the physical parameters of HD 174966 and carried a mode identification out from the spectroscopic and photometric observations. We used this information to look for the models fulfilling all the conditions and discussed the inaccuracies of the method because of the rotation effects. In a final step, we searched for patterns in the frequency set using a Fourier transform, discussed its origin, and studied the possibility of using the periodicity to obtain information about the physical parameters of the star.
Results. A total of 185 peaks were obtained from the Fourier analysis of the CoRoT light curve, all of which were reliable pulsating frequencies. From the spectroscopic observations, 18 oscillation modes were detected and identified, and the inclination angle (62.5°-17.5+7.5) and the rotational velocity of the star (142 km s-1) were estimated. From the multi-colour photometric observations, only three frequencies were detected that correspond to the main ones in the CoRoT light curve. We looked for periodicities within the 185 frequencies and found a quasiperiodic pattern Δν ~ 64 μHz. Using the inclination angle, the rotational velocity, and an Echelle diagram (showing a double comb outside the asymptotic regime), we concluded that the periodicity corresponds to a large separation structure. The quasiperiodic pattern allowed us to discriminate models from a grid. As a result, the value of the mean density is achieved with a 6% uncertainty. So, the Δν pattern could be used as a new observable for A-F type stars.
Key words: asteroseismology / stars: oscillations / stars: variables: delta Scuti / stars: interiors / stars: fundamental parameters / stars: rotation
The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA’s RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.
This work is based on ground-based observations made with the ESO 3.6 m telescope at La Silla Observatory under the ESO Large Programme LP182.D-0356, and on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), and on observations made at Observatoire de Haute Provence (CNRS), France, and at Observatorio de Sierra Nevada (OSN), Spain, operated by the Instituto de Astrofísica de Andalucía (CSIC). This research has made use of both the Simbad database, operated at CDS, Strasbourg, France, and the Astrophysics Data System, provided by NASA, USA.
Table 6 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A63
© ESO, 2013
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