Ground-based observations of the β Cephei CoRoT main target HD 180 642: abundance analysis and mode identification

Briquet, M.; Uytterhoeven, K.; Morel, T.; Aerts, C.; De Cat, P.; Mathias, P.; Lefever, K.; Miglio, A.; Poretti, E.; Martín-Ruiz, S.; Paparó, M.; Rainer, M.; Carrier, F.; Gutiérrez-Soto, J.; Valtier, J. C.; Benkő, J. M.; Bognár, Zs.; Niemczura, E.; Amado, P. J.; Suárez, J. C.; Moya, A.; Rodríguez-López, C.; Garrido, R.
Referencia bibliográfica

Astronomy and Astrophysics, Volume 506, Issue 1, 2009, pp.269-280

Fecha de publicación:
10
2009
Número de autores
23
Número de autores del IAC
1
Número de citas
35
Número de citas referidas
23
Descripción
The known β Cephei star HD 180 642 was observed by the CoRoT satellite in 2007. From the very high-precision light curve, its pulsation frequency spectrum could be derived for the first time (Degroote and collaborators). In this paper, we obtain additional constraints for forthcoming asteroseismic modeling of the target. Our results are based on both extensive ground-based multicolour photometry and high-resolution spectroscopy. We determine T_eff = 24 500± 1000 K and log g = 3.45± 0.15 dex from spectroscopy. The derived chemical abundances are consistent with those for B stars in the solar neighbourhood, except for a mild nitrogen excess. A metallicity Z = 0.0099± 0.0016 is obtained. Three modes are detected in photometry. The degree ℓ is unambiguously identified for two of them: ℓ = 0 and ℓ = 3 for the frequencies 5.48694 d-1 and 0.30818 d-1, respectively. The radial mode is non-linear and highly dominant with an amplitude in the U-filter about 15 times larger than the strongest of the other modes. For the third frequency of 7.36673 d-1 found in photometry, two possibilities remain: ℓ = 0 or 3. In the radial velocities, the dominant radial mode presents a so-called stillstand but no clear evidence of the existence of shocks is observed. Four low-amplitude modes are found in spectroscopy and one of them, with frequency 8.4079 d-1, is identified as (ℓ,m)=(3,2). Based on this mode identification, we finally deduce an equatorial rotational velocity of 38± 15 km s-1. Based on data gathered with the 1.2m Mercator telescope Roque de los Muchachos, La Palma, the 90cm telescope at Sierra Nevada Observatory, Spain, the 1.5 m telescope at San Pedro Mártir Observatory, Mexico, the 1m RCC and 50 cm telescope at the Piszkéstető Mountain Station of Konkoly Observatory, Hungary, the 2.2 m ESO telescope (ESO Programme 077.D-0311; ESO Large Programme 178.D-0361) at La Silla, Chile, the 1.93 m and 1.52 m telescopes at the Haute-Provence Observatory, France. Current address: Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot; CEA, IRFU, SAp, centre de Saclay, 91191 Gif-sur-Yvette, France.
Proyectos relacionados
Helio and Asteroseismologia
Sismología Solar y Estelar y Búsqueda de Exoplanetas
Los objetivos genéricos de este Proyecto son: 1) el estudio de la estructura y dinámica del interior solar, 2) la extensión de dicho estudio al caso de otras estrellas, 3) la búsqueda y caracterización de planetas extrasolares por métodos fotométricos (principalmente mediante el método de tránsitos) y espectroscópico (variaciones en la velocidad
Savita
Mathur