A UNIFORM ASTEROSEISMIC ANALYSIS OF 22 SOLAR-TYPE STARS OBSERVED BY<i>KEPLER</i>

Mathur, S.; Metcalfe, T. S.; Woitaszek, Matthew; Bruntt, H.; Verner, G. A.; Christensen‐Dalsgaard, J.; Creevey, O.; Doğan, G.; Basu, Sarbani; Karoff, C.; Stello, Dennis; Appourchaux, T.; Campante, Tiago L.; Chaplin, W. J.; García, Rafael A.; Bedding, Timothy R.; Benomar, O.; Bonanno, A.; Deheuvels, S.; Elsworth, Y.; Gaulme, P.; Guzik, Joyce A.; Handberg, R.; Hekker, S.; Herzberg, Wiebke; Monteiro, M. J. P. F. G.; Piau, L.; Quirion, Pierre-Olivier; Régulo, C.; Roth, M.; Salabert, D.; Serenelli, Aldo; Thompson, M. J.; Trampedach, Regner; White, T. R.; Ballot, J.; Brandão, I. M.; Molenda‐Żakowicz, J.; Kjeldsen, H.; Twicken, Joseph D.; Uddin, Kamal; Wohler, Bill

doi:10.1088/0004-637x/749/2/152

Cited by 191 publications

(255 citation statements)

References 89 publications

(96 reference statements)

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“…Indeed, asteroseismology has proved to allow age determination with a good precision (Christensen-Dalsgaard et al 2010;Mathur et al 2012;Metcalfe et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Chromospheric activity as age indicator

Pace

2013

A&A

146

106

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Context. Chromospheric activity has been calibrated and widely used as an age indicator. However, it has been suggested that the viability of this age indicator is, in the best case, limited to stars younger than about 1.5 Gyr. Aims. I aim to define the age range for which chromospheric activity is a robust astrophysical clock. Methods. I collected literature measurements of the S-index in field stars, which is a measure of the strength of the H and K lines of the Ca II and a proxy for chromospheric activity, and exploited the homogeneous database of temperature and age determinations for field stars provided by the Geneva-Copenhagen survey of the solar neighbourhood. Results. Field data, inclusive data previously used to calibrate chromospheric ages, confirm the result found using open cluster data, i.e. there is no decay of chromospheric activity after about 2 Gyr. Conclusions. The only existing indication supporting the viability of chromospheric ages older than 2 Gyr is the similarity of chromospheric activity levels in the components of 35 dwarf binaries. However, even in the most optimistic scenario, uncertainty in age determination for field stars and lack of sufficient data in open clusters make any attempt of calibrating an age activity relationship for old stars premature. The hypothesis that chromospheric activity follows the Skumanich law, i.e. that it is proportional to t −1/2 , should be relaxed.

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“…Indeed, asteroseismology has proved to allow age determination with a good precision (Christensen-Dalsgaard et al 2010;Mathur et al 2012;Metcalfe et al 2012).…”

Section: Discussionmentioning

confidence: 99%

Chromospheric activity as age indicator

Pace

2013

A&A

146

106

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“…This scaled powerlaw approach has been adopted widely (e.g. Tang & Gai 2011;Mathur et al 2012;Deheuvels et al 2012). However, the fit overpredicts the magnitude of the surface effect at lower frequencies (see Figs.…”

Section: Introductionmentioning

confidence: 99%

A new correction of stellar oscillation frequencies for near-surface effects

Ball

Gizon

2014

A&A

215

337

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Context. Space-based observations of solar-like oscillations present an opportunity to constrain stellar models using individual mode frequencies. However, current stellar models are inaccurate near the surface, which introduces a systematic difference that must be corrected. Aims. We introduce and evaluate two parametrizations of the surface corrections based on formulae given by Gough (1990, LNP, 367, 283). The first we call a cubic term proportional to ν 3 /I and the second has an additional inverse term proportional to ν −1 /I, where ν and I are the frequency and inertia of an oscillation mode. Methods. We first show that these formulae accurately correct model frequencies of two different solar models (Model S and a calibrated MESA model) when compared to observed BiSON frequencies. In particular, even the cubic form alone fits significantly better than a power law. We then incorporate the parametrizations into a modelling pipeline that simultaneously fits the surface effects and the underlying stellar model parameters. We apply this pipeline to synthetic observations of a Sun-like stellar model, solar observations degraded to typical asteroseismic uncertainties, and observations of the well-studied CoRoT target HD 52265. For comparison, we also run the pipeline with the scaled power-law correction proposed by Kjeldsen et al. (2008, ApJ, 683, L175). Results. The fits to synthetic and degraded solar data show that the method is unbiased and produces best-fit parameters that are consistent with the input models and known parameters of the Sun. Our results for HD 52265 are consistent with previous modelling efforts and the magnitude of the surface correction is similar to that of the Sun. The fit using a scaled power-law correction is significantly worse but yields consistent parameters, suggesting that HD 52265 is sufficiently Sun-like for the same power-law to be applicable. Conclusions. We find that the cubic term alone is suitable for asteroseismic applications and it is easy to implement in an existing pipeline. It reproduces the frequency dependence of the surface correction better than a power-law fit, both when comparing calibrated solar models to BiSON observations and when fitting stellar models using the individual frequencies. This parametrization is thus a useful new way to correct model frequencies so that observations of individual mode frequencies can be exploited.

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“…Stello et al 2013Stello et al , 2015Chaplin et al 2015). These data allow us to determine accurate stellar properties that help to constrain stellar evolution models (Metcalfe et al 2010;Mathur et al 2012) and improve the determination of the properties of the exoplanets they might host (Guillot & Havel 2011;Huber et al 2013). A review of the progress with Kepler in the field of the red giant stars can be found in Christensen-Dalsgaard (2012) and García & Stello (2015).…”

Section: Introductionmentioning

confidence: 99%

Asteroseismology of 19 low-luminosity red giant stars fromKepler

Hernández

García

Corsaro

et al. 2016

A&A

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Context. Frequencies of acoustic and mixed modes in red giant stars are now determined with high precision thanks to the long continuous observations provided by the NASA's Kepler mission. Here we consider the eigenfrequencies of nineteen low-luminosity red giant stars selected in a recent publication for a detailed peak-bagging analysis. Aims. Our objective is to obtain stellar parameters by using individual mode frequencies and spectroscopic information. Methods. We use a forward modelling technique based on a minimization procedure combining the frequencies of the p-modes, the period spacing of the dipolar modes, and the spectroscopic data. Results. Consistent results between the forward modelling technique and values derived from the seismic scaling relations are found but the errors derived using the former technique are lower. The average error for log g is 0.002 dex, compared to 0.011 dex from the frequency of maximum power, ν max , and 0.10 dex from the spectroscopic analysis. Relative errors in the masses and radii are on average 2% and 0.5% respectively, compared to 3% and 2% derived from the scaling relations. No reliable determination of the initial helium abundances and the mixing length parameters could be made. Finally, for our grid of models with given input physics, we found that low-mass stars require higher values of the overshooting parameter.

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A UNIFORM ASTEROSEISMIC ANALYSIS OF 22 SOLAR-TYPE STARS OBSERVED BYKEPLER

Cited by 191 publications

References 89 publications

Chromospheric activity as age indicator

Chromospheric activity as age indicator

A new correction of stellar oscillation frequencies for near-surface effects

Asteroseismology of 19 low-luminosity red giant stars fromKepler

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