Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175869

Gutiérrez‐Soto, J.; Floquet, M.; Samadi, R.; Neiner, C.; Garrido, R.; Fabregat, J.; Frémat, Y.; Diago, P. D.; Huat, Anne-Laure; Leroy, B.; Emílio, M.; Hubert, A. M.; Andrade, O. Thizy L.; Batz, B. de; Janot-Pacheco, E.; Lara, F. Espinosa; Martayan, Christophe; Semaan, T.; Suso, J.; Auvergne, M.; Chaintreuil, Sylviane; Michel, E.; Catala, C.

doi:10.1051/0004-6361/200911915

Cited by 36 publications

(45 citation statements)

References 31 publications

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“…2 we display the Fourier spectrum, showing the typical aliasing at the orbital frequency (as described in Gutiérrez-Soto et al 2009). From the frequency analysis, we obtain 60 significant frequencies which are listed in Table 2.…”

Section: Frequency Analysismentioning

confidence: 99%

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Pulsations in the late-type Be star HD 50 209 detected by CoRoT

Diago¹,

Gutiérrez‐Soto

Auvergne

et al. 2009

A&A

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Context. The presence of pulsations in late-type Be stars is still a matter of controversy. It constitutes an important issue to establish the relationship between non-radial pulsations and the mass-loss mechanism in Be stars. Aims. To contribute to this discussion, we analyse the photometric time series of the B8IVe star HD 50 209 observed by the CoRoT mission in the seismology field. Methods. We use standard Fourier techniques and linear and non-linear least squares fitting methods to analyse the CoRoT light curve. In addition, we applied detailed modelling of high-resolution spectra to obtain the fundamental physical parameters of the star. Results. We have found four frequencies which correspond to gravity modes with azimuthal order m = 0, −1, −2, −3 with the same pulsational frequency in the co-rotating frame. We also found a rotational period with a frequency of 0.679 cd −1 (7.754 μHz). Conclusions. HD 50 209 is a pulsating Be star as expected from its position in the HR diagram, close to the SPB instability strip.

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Section: Frequency Analysismentioning

confidence: 99%

“…All the techniques used in this paper are described in detail by Gutiérrez-Soto et al (2009). As mentioned in that paper, the orbital characteristics of the CoRoT satellite produces signal in the data at the orbital frequency (13.97 cd −1 , 161.689 μHz) and day/night peaks (2.007 cd −1 , 23.229 μHz) and their harmonics.…”

Section: Frequency Analysismentioning

confidence: 99%

Pulsations in the late-type Be star HD 50 209 detected by CoRoT

Diago¹,

Gutiérrez‐Soto

Auvergne

et al. 2009

A&A

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“…Since the noise decreases with frequency, it can thus miss peaks at high frequencies with S /N > 4 but low amplitudes. For a detailed description of these methods, we refer to Gutiérrez-Soto et al (2009). Frequencies found with these 3 methods, their amplitude and phase, as well as the interpretation of each frequency in terms of stellar signal or combinations, but excluding instrumental frequencies such as the orbital frequency of the satellite, are given in Table 5.…”

Section: Corot Photometric Datamentioning

confidence: 99%

“…The amplitudes and phases, and their errors, obtained for each set of frequencies with these three methods were recalculated with Amphi to achieve greater accuracy and homogeneity and are also given in Table 5. For a complete set of fixed frequencies, this program calculates the amplitudes and phases to obtain the best fit to the light curve (see Gutiérrez-Soto et al 2009). …”

Section: Corot Photometric Datamentioning

confidence: 99%

The pulsations of the B5IVe star HD 181231 observed with CoRoT and ground-based spectroscopy

Neiner¹,

Gutiérrez‐Soto²,

Baudin

et al. 2009

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Context. HD 181231 is a B5IVe star, which has been observed with the CoRoT satellite during ∼5 consecutive months and simultaneously from the ground in spectroscopy and spectropolarimetry. Aims. By analysing these data, we aim to detect and characterize as many pulsation frequencies as possible, to search for the presence of beating effects possibly at the origin of the Be phenomenon. Our results will also provide a basis for seismic modelling. Methods. The fundamental parameters of the star are determined from spectral fitting and from the study of the circumstellar emission. The CoRoT photometric data and ground-based spectroscopy are analysed using several Fourier techniques: Clean-ng, Pasper, and Tisaft, as well as a time-frequency technique. A search for a magnetic field is performed by applying the LSD technique to the spectropolarimetric data. Results. We find that HD 181231 is a B5IVe star seen with an inclination of ∼45 degrees. No magnetic field is detected in its photosphere. We detect at least 10 independent significant frequencies of variations among the 54 detected frequencies, interpreted in terms of non-radial pulsation modes and rotation. Two longer-term variations are also detected: one at ∼14 days resulting from a beating effect between the two main frequencies of short-term variations, the other at ∼116 days due either to a beating of frequencies or to a zonal pulsation mode. Conclusions. Our analysis of the CoRoT light curve and ground-based spectroscopic data of HD 181231 has led to the determination of the fundamental and pulsational parameters of the star, including beating effects. This will allow a precise seismic modelling of this star.

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“…A remarkable finding is the outburst signal detected in the B0.5IVe star HD 49330 (Huat et al 2009), a phenomenon that has not been observed to occur in any of the other observed Be stars, which are of later spectral type. Theoretical work is needed to understand and interpret the observed frequency patterns in the Be pulsators (Neiner et al 2009;Diago et al 2009;Gutiérrez-Soto et al 2009). Progress is hampered by the mathematical complexity of describing the oscillations in these flattened stars, induced by their rapid rotation, often close to their critical velocity.…”

Section: Introductionmentioning

confidence: 99%

Seismic modelling of theβ Cephei star HD 180642 (V1449 Aquilae)

Aerts

Briquet

Degroote

et al. 2011

A&A

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Context. We present modelling of the β Cep star HD 180642 based on its observational properties deduced from CoRoT and groundbased photometry as well as from time-resolved spectroscopy. Aims. We investigate whether present-day state-of-the-art models are able to explain the full seismic behaviour of this star, which has extended observational constraints for this type of pulsator. Methods. We constructed a dedicated database of stellar models and their oscillation modes tuned to fit the dominant radial mode frequency of HD 180642, by means of varying the hydrogen content, metallicity, mass, age, and core overshooting parameter. We compared the seismic properties of these models with those observed. Results. We find models that are able to explain the numerous observed oscillation properties of the star, for a narrow range in mass of 11.4-11.8 M and no or very mild overshooting (with up to 0.05 local pressure scale heights), except for an excitation problem of the = 3, p 1 mode. We deduce a rotation period of about 13 d, which is fully compatible with recent magnetic field measurements. The seismic models do not support the earlier claim of solar-like oscillations in the star. We instead ascribe the power excess at high frequency to non-linear resonant mode coupling between the high-amplitude radial fundamental mode and several of the low-order pressure modes. We report a discrepancy between the seismic and spectroscopic gravity at the 2.5σ level.

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Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175869

Cited by 36 publications

References 31 publications

Pulsations in the late-type Be star HD 50 209 detected by CoRoT

Pulsations in the late-type Be star HD 50 209 detected by CoRoT

The pulsations of the B5IVe star HD 181231 observed with CoRoT and ground-based spectroscopy

Seismic modelling of theβ Cephei star HD 180642 (V1449 Aquilae)

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