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See detailGround-based observations of the beta Cephei CoRoT main target HD 180 642: abundance analysis and mode identification
Briquet, Maryline ULg; Uytterhoeven, K.; Morel, Thierry ULg et al

in Astronomy and Astrophysics (2009), 506

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 ... [more ▼]

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 â is unambiguously identified for two of them: â = 0 and â = 3 for the frequencies 5.48694 d[SUP]-1[/SUP] and 0.30818 d[SUP]-1[/SUP], 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[SUP]-1[/SUP] found in photometry, two possibilities remain: â = 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[SUP]-1[/SUP], is identified as (â ,m)=(3,2). Based on this mode identification, we finally deduce an equatorial rotational velocity of 38± 15 km s[SUP]-1[/SUP]. 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 PiszkéstetÅ 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. [less ▲]

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See detailAn asteroseismic study of the beta Cephei CoRoT main target HD 180642: results from the ground-based campaign
Briquet, Maryline ULg; Uytterhoeven, K.; Morel, Thierry ULg et al

in American Institute of Physics Conference Series (2009, September 01)

The β Cephei star HD 180642 was observed by the CoRoT satellite during a run of 156 days in 2007. The space white light photometry revealed the rich frequency spectrum of the star (Degroote et al. 2009 ... [more ▼]

The β Cephei star HD 180642 was observed by the CoRoT satellite during a run of 156 days in 2007. The space white light photometry revealed the rich frequency spectrum of the star (Degroote et al. 2009). In the present study, we provide additional information on the target, based on both ground-based multi-colour photometry and high-resolution spectroscopy. We place our object in the (T[SUB]eff[/SUB], log g) diagram. In addition, we derive the chemical abundances of several elements as well as the metallicity of HD 180642. Finally, we put constraints on the identification of some modes. All these observational constraints will be used to compute stellar models of the target. [less ▲]

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See detailGround-based observations of the beta Cephei CoRoT main target HD 180642
Briquet, Maryline ULg; Uytterhoeven, K.; Aerts, C. et al

in Communications in Asteroseismology (2009), 158

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD~180642. Besides the non-linear dominant ... [more ▼]

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD~180642. Besides the non-linear dominant radial mode several low-amplitude modes are detected in both kinds of datasets. Our aim is to derive the wavenumbers (â ,m) of these modes, as additional constraints to the CoRoT pulsation frequencies, for forthcoming asteroseismic modelling of the star. [less ▲]

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See detailClose-up of primary and secondary asteroseismic CoRoT targets and the ground-based follow-up observations
Uytterhoeven, K.; Poretti, E.; Rainer, M. et al

in Journal of Physics Conference Series (2008), 118

To optimise the science results of the asteroseismic part of the CoRoT satellite mission a complementary simultaneous ground-based observational campaign is organised for selected CoRoT targets. The ... [more ▼]

To optimise the science results of the asteroseismic part of the CoRoT satellite mission a complementary simultaneous ground-based observational campaign is organised for selected CoRoT targets. The observations include both high-resolution spectroscopic and multicolour photometric data. We present the preliminary results of the analysis of the ground-based observations of three targets. A line-profile analysis of 216 high-resolution FEROS spectra of the δ Sct star HD 50844 reveals more than ten pulsation frequencies in the frequency range 5-18 d[SUP]-1[/SUP], including possibly one radial fundamental mode (6.92 d[SUP]-1[/SUP]). Based on more than 600 multi-colour photometric datapoints of the β Cep star HD 180642, spanning about three years and obtained with different telescopes and different instruments, we confirm the presence of a dominant radial mode ν[SUB]1[/SUB] = 5.48695 d[SUP]-1[/SUP], and detect also its first two harmonics. We find evidence for a second mode ν[SUB]2[/SUB] = 0.3017 d[SUP]-1[/SUP], possibly a g-mode, and indications for two more frequencies in the 7-8 d[SUP]-1[/SUP] domain. From Stromgren photometry we find evidence for the hybrid 5 Sct/γ Dor character of the F0 star HD 44195, as frequencies near 3 d[SUP]-1[/SUP] and 21 d[SUP]-1[/SUP] are detected simultaneously in the different filters. [less ▲]

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See detailGround-based observations of the beta Cephei CoRoT main target HD 180642
Briquet, Maryline ULg; Uytterhoeven, K.; Aerts, C. et al

Conference (2008, July)

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD 180642. Besides the non-linear dominant ... [more ▼]

We present the preliminary results of a detailed study of ground-based photometric and spectroscopic observations dedicated to the β Cephei CoRoT main target HD 180642. Besides the non-linear dominant radial mode several low-amplitude modes are detected in both kinds of datasets. Our aim is to derive the wavenumbers (ℓ,m) of these modes, as additional constraints to the CoRoT pulsation frequencies, for forthcoming asteroseismic modelling of the star. [less ▲]

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See detailBW Vulpeculae - A coordinated campaign of photoelectric photometry from thirteen observatories
Sterken, C.; Snowden, M.; Africano, J. et al

in Astronomy and Astrophysics. Supplement Series (1986), 66

This paper contains the fully reduced observational data on the Beta Cep star BW Vul, which were obtained in the summer of 1982 during an international campaign at thirteen observatories in the northern ... [more ▼]

This paper contains the fully reduced observational data on the Beta Cep star BW Vul, which were obtained in the summer of 1982 during an international campaign at thirteen observatories in the northern hemisphere. Useful measurements were made during a total of 486 hours. All observations have been assigned proper weights and were binned in time intervals of 90 seconds. In this manner the observations were combined into single data points which resulted in about 6000 mean differential measurements. A preliminary ephemeris for 1982 is derived, and a mean lightcurve is given. The results indicate a fair degree of stability in the shape and in the amplitude of the lightcurve. Possible variations exist in the morphology of the stillstand phenomenon. [less ▲]

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See detailThe international photometric observing campaign on BW Vul: first results.
Sterken, C.; Snowden, M.; Young, A. et al

in Theoretical Problems in Stellar Stability and Oscillations (1984)

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