Asteroseismology of 36 emph{Kepler} subgiants — I. Oscillation frequencies, linewidths and amplitudes. (arXiv:2005.06460v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Li_Y/0/1/0/all/0/1">Yaguang Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bedding_T/0/1/0/all/0/1">Timothy R. Bedding</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Li_T/0/1/0/all/0/1">Tanda Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bi_S/0/1/0/all/0/1">Shaolan Bi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stello_D/0/1/0/all/0/1">Dennis Stello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhou_Y/0/1/0/all/0/1">Yixiao Zhou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+White_T/0/1/0/all/0/1">Timothy R. White</a>
The presence of mixed modes makes subgiants excellent targets for
asteroseismology, providing a probe for the internal structure of stars. Here
we study 36 emph{Kepler} subgiants with solar-like oscillations and report
their oscillation mode parameters. We performed a so-called peakbagging
exercise, i.e. estimating oscillation mode frequencies, linewidths, and
amplitudes with a power spectrum model, fitted in the Bayesian framework and
sampled with a Markov Chain Monte Carlo algorithm. The uncertainties of the
mode frequencies have a median value of 0.180 $mu$Hz. We obtained seismic
parameters from the peakbagging, analysed their correlation with stellar
parameters, and examined against scaling relations. The behaviour of seismic
parameters (e.g. $Deltanu$, $nu_{rm max}$, $epsilon_p$) is in general
consistent with theoretical predictions. We presented the observational p–g
diagrams: $gamma_1$–$Deltanu$ for early subgiants and
$DeltaPi_1$–$Deltanu$ for late subgiants, and demonstrate their capability
to estimate stellar mass. We also found a $log g$ dependence on the linewidths
and a mass dependence on the oscillation amplitudes and the widths of
oscillation excess. This sample will be valuable constraints for modelling
stars and studying mode physics such as excitation and damping.
The presence of mixed modes makes subgiants excellent targets for
asteroseismology, providing a probe for the internal structure of stars. Here
we study 36 emph{Kepler} subgiants with solar-like oscillations and report
their oscillation mode parameters. We performed a so-called peakbagging
exercise, i.e. estimating oscillation mode frequencies, linewidths, and
amplitudes with a power spectrum model, fitted in the Bayesian framework and
sampled with a Markov Chain Monte Carlo algorithm. The uncertainties of the
mode frequencies have a median value of 0.180 $mu$Hz. We obtained seismic
parameters from the peakbagging, analysed their correlation with stellar
parameters, and examined against scaling relations. The behaviour of seismic
parameters (e.g. $Deltanu$, $nu_{rm max}$, $epsilon_p$) is in general
consistent with theoretical predictions. We presented the observational p–g
diagrams: $gamma_1$–$Deltanu$ for early subgiants and
$DeltaPi_1$–$Deltanu$ for late subgiants, and demonstrate their capability
to estimate stellar mass. We also found a $log g$ dependence on the linewidths
and a mass dependence on the oscillation amplitudes and the widths of
oscillation excess. This sample will be valuable constraints for modelling
stars and studying mode physics such as excitation and damping.
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