Bibcode
García, R. A.; De Ridder, J.; Corsaro, E.
Bibliographical reference
Astronomy and Astrophysics, Volume 579, id.A83, 76 pp.
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7
2015
Journal
Citations
78
Refereed citations
70
Description
Context. Non-radial oscillations, observed in thousands of red giants by
the space missions CoRoT and Kepler, allow us to greatly improve our
understanding of stellar structure and evolution in cool low-mass stars.
The currently available Kepler light curves contain an outstanding
amount of information, but a detailed analysis of the individual
oscillation modes in the observed power spectra, also known as peak
bagging, is computationally demanding and challenging to perform on a
large number of targets. Aims: Our intent is to perform for the
first time a peak bagging analysis on a sample of 19 low-mass
low-luminosity red giants observed by Kepler for more than four years.
This allows us to provide high-quality asteroseismic measurements that
can be exploited for an intensive testing of the physics used in stellar
structure models, stellar evolution, and pulsation codes, as well as for
refining existing asteroseismic scaling relations in the red giant
branch regime. Methods: For this purpose, powerful and
sophisticated analysis tools are needed. We exploit the Bayesian code
Diamonds, using an efficient nested sampling Monte Carlo algorithm, to
perform both a fast fitting of the individual oscillation modes and a
peak detection test based on the Bayesian evidence. Results: We
find good agreement for the parameters estimated in the background
fitting phase with those given in the literature. We extract and
characterize a total of 1618 oscillation modes, providing the largest
set of detailed asteroseismic mode measurements ever published. We
report on the evidence of a change in regime observed in the relation
between linewidths and effective temperatures of the stars occurring at
the bottom of the red giant branch. We show the presence of a linewidth
depression or plateau around νmax for all the red giants
of the sample. Lastly, we show a good agreement between our measurements
of maximum mode amplitudes and existing maximum amplitudes from global
analyses provided in the literature, proving that amplitude scaling
relations can be used as empirical tools to improve and simplify the
future peak bagging analysis on a larger sample of evolved stars.