Characterization of the power excess of solar-like oscillations in red giants with Kepler

By B. Mosser, Y. Elsworth, S. Hekker, D. Huber, T. Kallinger, S. Mathur, K. Belkacem, M. Goupil, R. Samadi, C. Barban and 8 more. 2011

168 citations recorded by the source corpus.

Context. The space mission Kepler provides us with long and uninterrupted photometric time series of red giants. This allows us to examine their seismic global properties and to compare these with theoretical predictions. Aims. We aim to describe the oscillation power excess observed in red giant oscillation spectra with global seismic parameters, and to investigate empirical scaling relations governing these parameters. From these scalings relations, we derive new physical properties of red giant oscillations. Methods. Various different methods were compared in order to validate the processes and to derive reliable output values. For consistency, a single method was then used to determine scaling relations for the relevant global asteroseismic parameters: mean mode height, mean height of the background signal superimposed on the oscillation power excess, width of the power excess, bolometric amplitude of the radial modes and visibility of non-radial modes. A method for deriving oscillation amplitudes is proposed, which relies on the complete identification of the red giant oscillation spectrum. Results. The comparison of the different methods has shown the important role of the way the background is modelled. The convergence reached by the collaborative work enables us to derive significant results concerning the oscillation power excess. We obtain several scaling relations, and identify the influence of the stellar mass and the evolutionary status. The effect of helium burning on the red giant interior structure is confirmed: it yields a strong mass-radius relation for clump stars. We find that none of the amplitude scaling relations motivated by physical considerations predict the observed mode amplitudes of red giant stars. In parallel, the degree-dependent mode visibility exhibits important variations. Both effects seem related to the significant influence of the high mode mass of non-radial mixed modes. A family of red giants with very weak dipole modes is identified, and its properties are analyzed. Conclusions. The clear correlation between the power densities of the background signal and of the stellar oscillation induces important consequences to be considered for deriving a reliable theoretical relation of the mode amplitude. As a by-product of this work, we have verified that red giant asteroseismology delivers new insights for stellar and Galactic physics, given the evidence for mass loss at the tip of the red giant branch.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/7f779d520ab7e0e4ef3219eaf9974597244489b4

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In Astronomy and Astrophysics

1. D. Huber
2. D. Stello
3. W. Chaplin
4. T. Bedding
5. A. Miglio
6. B. Mosser
7. E. Gaidos
8. A. Serenelli

Citations in the corpus

• Asteroseismology of 16,000 Kepler Red Giants: Global Oscillation Parameters, Masses, and Radii (2018, background): “Our results are in qualitative agreement with the predictions given by Kjeldsen & Bedding (2011), where higher-mass stars are expected to have lower oscillation amplitude and granulation power (Mosser et al. 2012a).”
• Asteroseismology of Solar-Type and Red-Giant Stars (2013, methodology): “…results have been obtained from peak-bagging (e.g., Baudin et al. 2011, Appourchaux et al. 2012) and from other techniques (Huber et al. 2011b, Mosser et al. 2012a) developed from ground-based analysis methods (e.g., Kjeldsen et al. 2008), including results on stars in open clusters (Stello…”
• REVISED STELLAR PROPERTIES OF KEPLER TARGETS FOR THE QUARTER 1–16 TRANSIT DETECTION RUN (2013, background): “…N. Cherry Ave., Tucson, AZ 85719, USA study of the core structure and rotation of subgiant and red-giant stars (Bedding et al. 2011; Beck et al. 2011; Mosser et al. 2012b; Deheuvels et al. 2012), an order of magnitude increase of known dwarf stars with detected oscillations (Chaplin et al. 2011),…”
• The connection between stellar granulation and oscillation as seen by the Kepler mission (2014, background): “…analysis of an individual star (di Mauro et al. 2011) and of the radial (Kallinger et al. 2012) and non-radial mixed mode spectra (Bedding et al. 2011; Mosser et al. 2012c), and how the latter are used to constrain rotational properties (Beck et al. 2012) and their evolution (Mosser et al. 2012b).”
• Probing the core structure and evolution of red giants using gravity-dominated mixed modes observed with Kepler (2012, methodology): “As already noted by Mosser et al. (2012), ℓ = 1 mixed modes are present in the region of ℓ = 3 modes, so that distinguishing true ℓ = 3 modes is difficult.”
• Standing on the Shoulders of Dwarfs: the Kepler Asteroseismic LEGACY Sample. I. Oscillation Mode Parameters (2016, background): “The comparisons do, however, qualitatively match those obtained by Mosser et al. (2012) for giants observed by Kepler ; the l = 3 modes disagree most with theory in their results too.”
• Spin down of the core rotation in red giants (2012, methodology): “The model indicates that the coefficient η decreases towards unity when a star evolves along the RGB, due to the significant increase of the gravity radial orders605 (Mosser et al. 2012c).”
• Revised Radii of Kepler Stars and Planets Using Gaia Data Release 2 (2018, background): “…presented here will thus aid in increasing cool dwarf samples for studies of stellar rotation and activity (e.g. McQuillan et al. 2014; Angus et al. 2016; Davenport 2016) and red giants for asteroseismology (e.g. Hekker et al. 2011; Mosser et al. 2012; Stello et al. 2013; Yu et al. 2018).”
• FUNDAMENTAL PROPERTIES OF KEPLER PLANET-CANDIDATE HOST STARS USING ASTEROSEISMOLOGY (2013, unknown): “In addition, oscillation timescales scale with stellar luminosity, with frequencies for red giants falling well below the long-cadence Nyquist limit (see, e.g., Bedding et al. 2010; Hekker et al. 2011b; Mosser et al. 2012).”