The advent of space-based missions like Kepler has revolutionized the study of solar-type stars, particularly through the measurement and modeling of their resonant modes of oscillation. Here we ...analyze a sample of 66 Kepler main-sequence stars showing solar-like oscillations as part of the Kepler seismic LEGACY project. We use Kepler short-cadence data, of which each star has at least 12 months, to create frequency-power spectra optimized for asteroseismology. For each star, we identify its modes of oscillation and extract parameters such as frequency, amplitude, and line width using a Bayesian Markov chain Monte Carlo "peak-bagging" approach. We report the extracted mode parameters for all 66 stars, as well as derived quantities such as frequency difference ratios, the large and small separations and the behavior of line widths with frequency and line widths at with , for which we derive parametrizations; and behavior of mode visibilities. These average properties can be applied in future peak-bagging exercises to better constrain the parameters of the stellar oscillation spectra. The frequencies and frequency ratios can tightly constrain the fundamental parameters of these solar-type stars, and mode line widths and amplitudes can test models of mode damping and excitation.
We use asteroseismic data from the Kepler satellite to determine fundamental stellar properties of the 66 main-sequence targets observed for at least one full year by the mission. We distributed tens ...of individual oscillation frequencies extracted from the time series of each star among seven modeling teams who applied different methods to determine radii, masses, and ages for all stars in the sample. Comparisons among the different results reveal a good level of agreement in all stellar properties, which is remarkable considering the variety of codes, input physics, and analysis methods employed by the different teams. Average uncertainties are of the order of ∼2% in radius, ∼4% in mass, and ∼10% in age, making this the best-characterized sample of main-sequence stars available to date. Our predicted initial abundances and mixing-length parameters are checked against inferences from chemical enrichment laws ΔY/ΔZ and predictions from 3D atmospheric simulations. We test the accuracy of the determined stellar properties by comparing them to the Sun, angular diameter measurements, Gaia parallaxes, and binary evolution, finding excellent agreement in all cases and further confirming the robustness of asteroseismically determined physical parameters of stars when individual frequencies of oscillation are available. Baptised as the Kepler dwarfs LEGACY sample, these stars are the solar-like oscillators with the best asteroseismic properties available for at least another decade. All data used in this analysis and the resulting stellar parameters are made publicly available for the community.
In this erratum, we provide corrected sets of r 01,10,02 difference ratio values and associated uncertainties, which were overestimated in the original paper (as noted by Roxburgh 2017) due to a ...missing trimming in the post-processing of the Markov chain Monte Carlo (MCMC) chains for these values. The typical reduction in the ratio uncertainties from performing the trimming is a factor of 10 (see Figure 3). Other parameters optimized in the peak-bagging (for instance, individual mode frequencies) are unaffected, as the trimming was performed for these in the original work (Lund et al. 2017). We also provide updated values for the n D 2 values of l=3 modes. We note that the values presented here, as with those presented in the original work, are obtained from a single peak-bagging procedure (see Lund et al. 2017 for details) and have yet to be verified by independent analyses using the same input power spectra. Examples of the updated tables from the original paper are given in Tables 1-3. We note that tables with individual mode parameters (Table 2) have been added for completeness, but the parameters in these tables are unchanged compared to the original paper. In addition to the corrected values mentioned above, we provide covariance matrices for the mode frequencies, frequency difference ratios (r 01,10,02), and second differences (n D 2) for the LEGACY sample (Lund et al. 2017), which were not published with the original work. The values provided by this erratum will be available in the online version of the paper. Figure 1. Comparison between ratio distribution of = r n 01, 25 (n » m 3090 Hz) for KIC 9139151 from the full (green) and properly thinned MCMC chains (black). The dashed red line (on top of the black curve) shows the distribution obtained by sampling from the reported frequency values and corresponding uncertainties (assuming that these are normally distributed and uncorrelated). The central peak is captured by both distributions, but the wide background signal representing the ratio prior has disappeared from the thinned chains. Dotted lines indicate the distribution medians; dashed lines bound the corresponding 68% highest probability density intervals.
Since the onset of the "space revolution" of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archeology investigations. The ...launch of the NASA Transiting Exoplanet Survey Satellite (TESS) mission has enabled seismic-based inferences to go full sky-providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5%-10%, and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data.
Abstract
We present an in-depth analysis of the bright subgiant HR 7322 (KIC 10005473) using Kepler short-cadence photometry, optical interferometry from CHARA, high-resolution spectra from SONG, and ...stellar modelling using garstec grids, and the Bayesian grid-fitting algorithm basta. HR 7322 is only the second subgiant with high-quality Kepler asteroseismology for which we also have interferometric data. We find a limb-darkened angular diameter of 0.443 ± 0.007 mas, which, combined with a distance derived using the parallax from Gaia DR2 and a bolometric flux, yields a linear radius of 2.00 ± 0.03 R⊙ and an effective temperature of 6350 ± 90 K. HR 7322 exhibits solar-like oscillations, and using the asteroseismic scaling relations and revisions thereof, we find good agreement between asteroseismic and interferometric stellar radius. The level of precision reached by the careful modelling is to a great extent due to the presence of an avoided crossing in the dipole oscillation mode pattern of HR 7322. We find that the standard models predict a stellar radius systematically smaller than the observed interferometric one and that a sub-solar mixing length parameter is needed to achieve a good fit to individual oscillation frequencies, interferometric temperature, and spectroscopic metallicity.
ABSTRACT
The Transiting Exoplanet Survey Satellite (TESS) is recording short-cadence, high duty-cycle timeseries across most of the sky, which presents the opportunity to detect and study ...oscillations in interesting stars, in particular planet hosts. We have detected and analysed solar-like oscillations in the bright G4 subgiant HD 38529, which hosts an inner, roughly Jupiter-mass planet on a $14.3\, \mathrm{d}$ orbit and an outer, low-mass brown dwarf on a $2136\, \mathrm{d}$ orbit. We combine results from multiple stellar modelling teams to produce robust asteroseismic estimates of the star’s properties, including its mass $M=1.48\pm 0.04\, \mathrm{M}_\odot {}$, radius $R=2.68\pm 0.03\, \mathrm{R}_\odot {}$, and age $t=3.07\pm 0.39\, \mathrm{Gyr}{}$. Our results confirm that HD 38529 has a mass near the higher end of the range that can be found in the literature and also demonstrate that precise stellar properties can be measured given shorter timeseries than produced by CoRoT, Kepler, or K2.
We present the discovery of HD 221416 b, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. HD 221416 ...b (HIP 116158, TOI-197) is a bright (V = 8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 Hz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (R = 2.943 0.064 R ), mass (M = 1.212 0.074 M ), and age (4.9 1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a "hot Saturn" (Rp = 9.17 0.33 R⊕) with an orbital period of ∼14.3 days, irradiance of F = 343 24 F⊕, and moderate mass (Mp = 60.5 5.7 M⊕) and density ( p = 0.431 0.062 g cm−3). The properties of HD 221416 b show that the host-star metallicity-planet mass correlation found in sub-Saturns (4-8 R⊕) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to ∼15%, HD 221416 b is one of the best characterized Saturn-size planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology.
Since the onset of the `space revolution' of high-precision high-cadence photometry, asteroseismology has been demonstrated as a powerful tool for informing Galactic archaeology investigations. The ...launch of the NASA TESS mission has enabled seismic-based inferences to go full sky -- providing a clear advantage for large ensemble studies of the different Milky Way components. Here we demonstrate its potential for investigating the Galaxy by carrying out the first asteroseismic ensemble study of red giant stars observed by TESS. We use a sample of 25 stars for which we measure their global asteroseimic observables and estimate their fundamental stellar properties, such as radius, mass, and age. Significant improvements are seen in the uncertainties of our estimates when combining seismic observables from TESS with astrometric measurements from the Gaia mission compared to when the seismology and astrometry are applied separately. Specifically, when combined we show that stellar radii can be determined to a precision of a few percent, masses to 5-10% and ages to the 20% level. This is comparable to the precision typically obtained using end-of-mission Kepler data
The advent of space-based missions like $Kepler$ has revolutionized the study
of solar-type stars, particularly through the measurement and modeling of their
resonant modes of oscillation. Here we ...analyze a sample of 66 $Kepler$
main-sequence stars showing solar-like oscillations as part of the $Kepler$
seismic LEGACY project. We use $Kepler$ short-cadence data, of which each star
has at least 12 months, to create frequency power spectra optimized for
asteroseismology. For each star we identify its modes of oscillation and
extract parameters such as frequency, amplitude, and line width using a
Bayesian Markov chain Monte Carlo `peak-bagging' approach. We report the
extracted mode parameters for all 66 stars, as well as derived quantities such
as frequency difference ratios, the large and small separations $\Delta\nu$ and
$\delta\nu_{02}$; the behavior of line widths with frequency and line widths at
$\nu_{\rm max}$ with $T_{\rm eff}$, for which we derive parametrizations; and
behavior of mode visibilities. These average properties can be applied in
future peak-bagging exercises to better constrain the parameters of the stellar
oscillation spectra. The frequencies and frequency ratios can tightly constrain
the fundamental parameters of these solar-type stars, and mode line widths and
amplitudes can test models of mode damping and excitation.
PDF
