Rotation speed and stellar axis inclination from p modes: how CoRoT would see other suns

Ballot, J.; García, R. A.; Lambert, Pascal

doi:10.1111/j.1365-2966.2006.10375.x

Cited by 123 publications

(113 citation statements)

References 21 publications

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“…The splitting parameter is difficult to estimate because when modes have large line widths, blending of the components of multiplets, and even of adjacent = 2 and l = 0 modes, results. This blending creates a strong correlation of the splitting parameter with the inclination parameter, making it difficult to disentangle the two (Ballot et al 2006(Ballot et al , 2008. A global fitting, as performed in this paper, can help to alleviate some of these problems.…”

Section: Resultsmentioning

confidence: 99%

Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data

Barban¹,

Deheuvels²,

Baudin

et al. 2009

A&A

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127

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Context. The estimate of solar-like oscillation properties, such as their frequencies, amplitudes and lifetimes, is challenging because of their low amplitudes and will benefit from long and uninterrupted observing runs. The space telescope CoRoT allows us to obtain high-performance photometric data over a long and quasi continuous period. Among its main targets are stars for which we expect solar-like oscillations. Aims. HD 181420, an F2 main sequence star, has been observed by CoRoT during its first long run covering about 156 days. With this unprecedently high-quality set of data, our aim is to derive the p-mode parameters that can be used to probe the stellar interior. Methods. The CoRoT data obtained on HD 181420 is analysed using a classical Fourier approach for the search for the p mode signature. The p-mode parameters are then derived using global fitting of the power spectrum by a Lorentzian model, as used widely in the solar case. Results. From the p-mode frequencies, the mean value of the large spacing is estimated to be 75 μHz. The p-mode amplitudes are slightly less than 4 ppm with a line width of about 8 μHz at the maximum of the p modes. The inclination angle is estimated to be around 45 • . The large mode line-width combined with the observed mode spacing make it difficult to identify the = 2 modes and to estimate the rotational splitting. We explore two scenarios for the identification of the modes.

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Section: Resultsmentioning

confidence: 99%

Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data

Barban¹,

Deheuvels²,

Baudin

et al. 2009

A&A

Self Cite

127

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“…We also find evidence of differential rotation, and show that independent measurements of the star inclination will be of great help in inferring the rate of differential rotation. Spot modeling may then achieve complementary results to asteroseismology (Gizon & Solanki 2004;Ballot et al 2006). A dedicated analysis of differential rotation will be presented in a forthcoming work.…”

Section: Resultsmentioning

confidence: 99%

Short-lived spots in solar-like stars as observed by CoRoT

Mosser¹,

Baudin

Lanza

et al. 2009

A&A

116

119

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Context. CoRoT light curves have an unprecedented photometric quality, having simultaneously a high signal-to-noise ratio, a long time span and a nearly continuous duty-cycle. Aims. We analyse the light-curves of four bright targets observed in the seismology field and study short-lived small spots in solar-like stars.Methods. We present a simple spot modeling by iterative analysis. Its ability to extract relevant parameters is ensured by implementing relaxation steps to avoid convergence to local minima of the sum of the residuals between observations and modeling. The use of Monte-Carlo simulations allows us to estimate the performance of the fits. Results. Our starspot modeling gives a representation of the spots on these stars in agreement with other well tested methods. Within this framework, parameters such as rigid-body rotation and spot lifetimes seem to be precisely determined. Then, the lifetime/rotation period ratios are in the range 0.5−2, and there is clear evidence for differential rotation.

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“…Assuming an equal repartition of the energy in the modes of different degrees , and taking the value of the limb darkening for this star into account, we obtain H =1,n /H =0,n = 1.5 H =2,n /H =0,n = 0.5 H =3,n /H =0,n = 0.05, where H =1,n = m=+ m=− H n, ,m . Inside non-radial multiplets, the heights H n, ,m are given by the intensity visibilities (see Gizon & Solanki 2003;Ballot et al 2006). …”

Section: Methodsmentioning

confidence: 99%

Seismic and spectroscopic characterization of the solar-like pulsating CoRoT target HD 49385

Deheuvels

Bruntt

Michel

et al. 2010

A&A

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115

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Context. The star HD 49385 is the first G-type solar-like pulsator observed in the seismology field of the space telescope CoRoT. The satellite collected 137 days of high-precision photometric data on this star, confirming that it presents solar-like oscillations. HD 49385 was also observed in spectroscopy with the NARVAL spectrograph in January 2009. Aims. Our goal is to characterize HD 49385 using both spectroscopic and seismic data. Methods. The fundamental stellar parameters of HD 49385 are derived with the semi-automatic software VWA, and the projected rotational velocity is estimated by fitting synthetic profiles to isolated lines in the observed spectrum. A maximum likelihood estimation is used to determine the parameters of the observed p modes. We perform a global fit, in which modes are fitted simultaneously over nine radial orders, with degrees ranging from = 0 to = 3 (36 individual modes). Results. Precise estimates of the atmospheric parameters (T eff , [M/H], log g) and of the v sin i of HD 49385 are obtained. The seismic analysis of the star leads to a clear identification of the modes for degrees = 0, 1, 2. Around the maximum of the signal (ν 1013 μHz), some peaks are found significant and compatible with the expected characteristics of = 3 modes. Our fit yields robust estimates of the frequencies, linewidths and amplitudes of the modes. We find amplitudes of ∼5.6 ± 0.8 ppm for radial modes at the maximum of the signal. The lifetimes of the modes range from one day (at high frequency) to a bit more than two days (at low frequency). Significant peaks are found outside the identified ridges and are fitted. They are attributed to mixed modes.

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Rotation speed and stellar axis inclination from p modes: how CoRoT would see other suns

Cited by 123 publications

References 21 publications

Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data

Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data

Short-lived spots in solar-like stars as observed by CoRoT

Seismic and spectroscopic characterization of the solar-like pulsating CoRoT target HD 49385

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