Bibcode
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
Revista
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.
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