High-precision CoRoT space photometry and fundamental parameter determination of the B2.5V star HD 48977

Thoul, Anne; Degroote, P.; Catala, C.; Aerts, C.; Morel, Thierry; Briquet, Maryline; Hillen, M.; Raskin, Gert; Winckel, H. Van; Auvergne, M.; Baglin, A.; Baudin, F.; Michel, E.

doi:10.1051/0004-6361/201118756

Cited by 18 publications

(17 citation statements)

References 57 publications

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“…The star rotates at about half its critical velocity and shows clear evidence of rotational modulation in addition to its pulsational variability in both the photometry and the spectroscopy. The list of B-type stars with a detected mixture of rotational and pulsational variability with similar frequencies and amplitudes is growing and occurs across all effective temperatures of this spectral type (e.g., Uytterhoeven et al 2005;Degroote et al 2011;Thoul et al 2012). This is not surprising given the co-existence of chemically peculiar Bp and SPB stars in the same part of the HR diagram (e.g., Briquet et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317

Pápics

Briquet

Baglin

et al. 2012

A&A

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Context. OB stars are important building blocks of the Universe, but we have only a limited sample of them well understood enough from an asteroseismological point of view to provide feedback on the current evolutionary models. Our study adds one special case to this sample, with more observational constraints than for most of these stars. Aims. Our goal is to analyse and interpret the pulsational behaviour of the B3 IV star HD 43317 using the CoRoT light curve along with the ground-based spectroscopy gathered by the HARPS instrument. This way we continue our efforts to map the β Cep and SPB instability strips. Methods. We used different techniques to reveal the abundances and fundamental stellar parameters from the newly-obtained highresolution spectra. We used various time-series analysis tools to explore the nature of variations present in the light curve. We calculated the moments and used the pixel-by-pixel method to look for line profile variations in the high-resolution spectra. Results. We find that HD 43317 is a single fast rotator (v rot ≈ 50% v crit ) and hybrid SPB/β Cep-type pulsator with Solar metal abundances. We interpret the variations in photometry and spectroscopy as a result of rotational modulation connected to surface inhomogeneities, combined with the presence of both g and p mode pulsations. We detect a series of ten consecutive frequencies with an almost constant period spacing of 6339 s as well as a second shorter sequence consisting of seven frequencies with a spacing of 6380 s. The dominant frequencies fall in the regime of gravito-inertial modes.

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Section: Discussionmentioning

confidence: 99%

Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317

Pápics

Briquet

Baglin

et al. 2012

A&A

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115

146

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“…Figure 5), we conclude that the observed correlation is due to stellar pulsations rather than rotational modulation. Moreover, besides the above mentioned correlation for the rotation frequency, one would also expect the rotational modulation to show up with series of harmonics of that frequency (see e.g., Thoul et al 2013). We thus checked how many harmonics in total (including those of combination frequencies) per star could be detected and present the distribution in Figure 8 (top).…”

Section: Fundamental Parameters and Position In The Hr Diagrammentioning

confidence: 96%

Detection of a large sample ofγDoradus stars fromKeplerspace photometry and high-resolution ground-based spectroscopy

Tkachenko

Aerts

Yakushechkin

et al. 2013

A&A

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Context. The launches of the MOST, CoRoT, and Kepler missions opened up a new era in asteroseismology, the study of stellar interiors via interpretation of pulsation patterns observed at the surfaces of large groups of stars. These space-missions deliver a huge amount of high-quality photometric data suitable to study numerous pulsating stars. Aims. Our ultimate goal is a detection and analysis of an extended sample of γ Dor-type pulsating stars with the aim to search for observational evidence of non-uniform period spacings and rotational splittings of gravity modes in main-sequence stars typically twice as massive as the Sun. This kind of diagnostic can be used to deduce the internal rotation law and to estimate the amount of rotational mixing in the near core regions. Methods. We applied an automated supervised photometric classification method to select a sample of 69 Gamma Doradus (γ Dor) candidate stars. We used an advanced method to extract the Kepler light curves from the pixel data information using custom masks. For 36 of the stars, we obtained high-resolution spectroscopy with the HERMES spectrograph installed at the Mercator telescope. The spectroscopic data are analysed to determine the fundamental parameters like T eff , log g, v sin i, and [M/H]. Results. We find that all stars for which spectroscopic estimates of T eff and log g are available fall into the region of the HR diagram where the γ Dor and δ Sct instability strips overlap. The stars cluster in a 700 K window in effective temperature, log g measurements suggest luminosity class IV-V, i.e. sub-giant or main-sequence stars. From the Kepler photometry, we identify 45 γ Dor-type pulsators, 14 γ Dor/δ Sct hybrids, and 10 stars which are classified as "possibly γ Dor/δ Sct hybrid pulsators". We find a clear correlation between the spectroscopically derived v sin i and the frequencies of independent pulsation modes. Conclusions. We have shown that our photometric classification based on the light curve morphology and colour information is very robust. The results of spectroscopic classification are in perfect agreement with the photometric classification. We show that the detected correlation between v sin i and frequencies has nothing to do with rotational modulation of the stars but is related to their stellar pulsations. Our sample and frequency determinations offer a good starting point for seismic modelling of slow to moderately rotating γ Dor stars.

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“…The frequency at 0.159 days −1 is present in both quarters; however, at the end of Q8, the amplitude at this frequency starts to diminish, a temporal variability consistent with a changing activity cycle. Rotational frequencies may also be distinguished from g-mode frequencies if the modes behave linearly (see, e.g., Thoul et al 2013) becausethe rotational frequency would occur with multiple harmonics, whereas the g-mode frequency would not.…”

Section: Search For G Modes In θ Cyg Datamentioning

confidence: 99%

Detection of Solar-Like Oscillations, Observational Constraints, and Stellar Models for Θ Cyg, the Brightest Star Observed by the Kepler Mission

Guzik

Houdek

Chaplin

et al. 2016

ApJ

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θCygni is an F3 spectral type magnitude V=4.48 main-sequence star that was the brightest star observed by the original Kepler spacecraft mission. Short-cadence (58.8 s) photometric data using a custom aperture were first obtained during Quarter 6 (2010 June-September)and subsequently in Quarters 8 and 12-17. We present analyses of solar-like oscillations based on Q6 and Q8 data, identifying angular degree l=0, 1, and 2 modes with frequencies of 1000-2700 μHz, a large frequency separationof 83.9±0.4 μHz, and maximum oscillation amplitude at frequency ν max =1829±54 μHz. We also present analyses of new ground-based spectroscopic observations, which, combined with interferometric angular diameter measurements, give T eff = 6697±78 K, radius 1.49±0.03 R e , [Fe/H]=−0.02±0.06 dex, and log g = 4.23±0.03. We calculate stellar models matching these constraints using the Yale Rotating Evolution Code and the Asteroseismic Modeling Portal. The best-fit models have masses of 1.35-1.39 M e and ages of 1.0-1.6 Gyr. θCyg's T eff and log g place it cooler than the red edge of the γ Doradus instability region established from pre-Kepler ground-based observations, but just at the red edge derived from pulsation modeling. The pulsation models show γ Dor gravity modes driven by the

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High-precision CoRoT space photometry and fundamental parameter determination of the B2.5V star HD 48977

Cited by 18 publications

References 57 publications

Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317

Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317

Detection of a large sample ofγDoradus stars fromKeplerspace photometry and high-resolution ground-based spectroscopy

Detection of Solar-Like Oscillations, Observational Constraints, and Stellar Models for Θ Cyg, the Brightest Star Observed by the Kepler Mission

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