Observations and interpretation of solar‐like oscillations in red‐giant stars

Hekker, S.

doi:10.1002/asna.201011446

Cited by 7 publications

(5 citation statements)

References 32 publications

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“…The RV variations over a wide range of timescales and amplitudes observed in giant stars can be caused by a variety of phenomena, including orbital dynamics, processes that are intrinsic to the star, such as stellar oscillations or spot activity coupled with stellar rotation, and other effects that may still await identification. For example, as shown by the CoRoT and Kepler photometry of giants, both radial and non-radial oscillations are common in these stars (de Ridder et al 2009;Hekker 2010;Baudin et al 2011;Gilliland et al 2011). In fact, p-mode oscillations have been identified in high-cadence RV measurements of several of them (e.g.…”

Section: Introductionmentioning

confidence: 99%

Substellar-Mass Companions to the K-Giants Hd 240237, Bd +48 738, and Hd 96127

Gettel

Wolszczan

Niedzielski

et al. 2011

ApJ

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We present the discovery of substellar-mass companions to three giant stars by the ongoing Penn State-Toruń Planet Search (PTPS) conducted with the 9.2 m Hobby-Eberly Telescope. The most massive of the three stars, K2-giant HD 240237, has a 5.3 M J minimum mass companion orbiting the star at a 746-day period. The K0-giant BD +48 738 is orbited by a ≥ 0.91 M J planet which has a period of 393 days and shows a non-linear, long-term radial velocity trend that indicates a presence of another, more distant companion, which may have a substellar mass or be a low-mass star. The K2-giant HD 96127, has a ≥ 4.0 M J mass companion in a 647-day orbit around the star. The two K2-giants exhibit a significant RV noise that complicates the detection of low-amplitude, periodic variations in the data. If the noise component of the observed RV variations is due to solar-type oscillations, we show, using all the published data for the substellar companions to giants, that its amplitude is anti-correlated with stellar metallicity.

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Section: Introductionmentioning

confidence: 99%

Substellar-Mass Companions to the K-Giants Hd 240237, Bd +48 738, and Hd 96127

Gettel

Wolszczan

Niedzielski

et al. 2011

ApJ

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“…the data have been analysed to search for solar‐like oscillations. For a recent review of solar‐like oscillations in red giant stars we refer to Hekker (2010), while the following papers present recent results from the Kepler (e.g. Bedding et al 2010; Huber et al 2010; Kallinger et al 2010b; Hekker et al 2010c) and CoRoT (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…In this work we characterise the red-giant stars using asteroseismology, i.e., the data have been analysed to search for solar-like oscillations. For a recent review of solar-like oscillations in red-giant stars we refer to Hekker (2010), while the following papers present recent results from the Kepler (e.g., Bedding et al 2010;Huber et al 2010;Kallinger et al 2010a;Hekker et al 2010c) and CoRoT (e.g., De Ridder et al 2009;Hekker et al 2009;Miglio et al 2009;Carrier et al 2010;Kallinger et al 2010b;Miglio et al 2010; E-mail: S.Hekker@uva.nl; A table with results is available upon request from the first author. 1 http://archive.stsci.edu/pub/kepler/lightcurves/tarfiles/ 2010; Hekker et al 2010a) missions.…”

Section: Introductionmentioning

confidence: 99%

Characterization of red giant stars in the public Kepler data

Hekker

Gilliland

Elsworth

et al. 2011

Monthly Notices of the Royal Astronomical Society

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108

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The first public release of long‐cadence stellar photometric data collected by the NASA Kepler mission has now been made available. In this paper, we characterize the red giant (G‐K) stars in this large sample in terms of their solar‐like oscillations. We use published methods and well‐known scaling relations in the analysis. Just over 70 per cent of the red giants in the sample show detectable solar‐like oscillations, and from these oscillations we are able to estimate the fundamental properties of the stars. This asteroseismic analysis reveals different populations: low‐luminosity H‐shell burning red giant branch stars, cool high‐luminosity red giants on the red giant branch and He‐core burning clump and secondary‐clump giants.

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“…Stars with turbulent outer layers are expected to exhibit solar-like oscillations and these are indeed observed in solartype stars, subgiants and G-K red-giant stars. For recent overviews of these observations and interpretations see e.g., Bedding & Kjeldsen (2008); Hekker (2010).…”

Section: Introductionmentioning

confidence: 99%

Solar-like oscillations in red giants observed withKepler: comparison of global oscillation parameters from different methods

Hekker

Elsworth

Ridder

et al. 2010

A&A

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108

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Context. The large number of stars for which uninterrupted high-precision photometric timeseries data are being collected with Kepler and CoRoT initiated the development of automated methods to analyse the stochastically excited oscillations in main-sequence, subgiant and red-giant stars. Aims. We investigate the differences in results for global oscillation parameters of G and K red-giant stars due to different methods and definitions. We also investigate uncertainties originating from the stochastic nature of the oscillations. Methods. For this investigation we use Kepler data obtained during the first four months of operation. These data have been analysed by different groups using already published methods and the results are compared. We also performed simulations to investigate the uncertainty on the resulting parameters due to different realizations of the stochastic signal. Results. We obtain results for the frequency of maximum oscillation power (ν max ) and the mean large separation ( Δν ) from different methods for over one thousand red-giant stars. The results for these parameters agree within a few percent and seem therefore robust to the different analysis methods and definitions used here. The uncertainties for ν max and Δν due to differences in realization noise are not negligible and should be taken into account when using these results for stellar modelling.

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Observations and interpretation of solar‐like oscillations in red‐giant stars

Cited by 7 publications

References 32 publications

Substellar-Mass Companions to the K-Giants Hd 240237, Bd +48 738, and Hd 96127

Substellar-Mass Companions to the K-Giants Hd 240237, Bd +48 738, and Hd 96127

Characterization of red giant stars in the public Kepler data

Solar-like oscillations in red giants observed withKepler: comparison of global oscillation parameters from different methods

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