Detection of Solar-like oscillations in the G7 giant star
<i>ξ</i> Hya

Frandsen, S.; Carrier, F.; Aerts, C.; Stello, Dennis; Maas, T.; Burnet, M.; Bruntt, H.; Teixeira, T. C.; Medeiros, Deusdedit Monteiro; Bouchy, F.; Kjeldsen, H.; Pijpers, F. P.; Christensen‐Dalsgaard, J.

doi:10.1051/0004-6361:20021281

Cited by 181 publications

(194 citation statements)

References 12 publications

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“…These solar-like oscillations correspond to pressure modes (p modes), and their frequencies follow a characteristic comb-like pattern (Tassoul 1980). The mode amplitudes range from a few tens to a few hundred parts per million (ppm) in observed flux, or of the order of 10 m s −1 or less in radial velocity (Frandsen et al 2002;De Ridder et al 2006), which is barely detectable from ground-based observations. In the era before high-precision photometric space missions, solar-like oscillations of red giants were only confirmed in a handful of bright stars from extensive single-and multisite campaigns of highprecision spectroscopy.…”

Section: Fig 1 Five Examples Ofmentioning

confidence: 99%

Pulsating red giant stars in eccentric binary systems discovered fromKeplerspace-based photometry

Beck

Hambleton

Vos

et al. 2014

A&A

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136

151

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Context. The unparalleled photometric data obtained by NASA's Kepler Space Telescope has led to improved understanding of red giant stars and binary stars. Seismology allows us to constrain the properties of red giants. In addition to eclipsing binaries, eccentric non-eclipsing binaries that exhibit ellipsoidal modulations have been detected with Kepler. Aims. We aim to study the properties of eccentric binary systems containing a red giant star and to derive the parameters of the primary giant component. Methods. We applied asteroseismic techniques to determine the masses and radii of the primary component of each system. For a selected target, light and radial velocity curve modelling techniques were applied to extract the parameters of the system and its primary component. Stellar evolution and its effects on the evolution of the binary system were studied from theoretical models. Results. The paper presents the asteroseismic analysis of 18 pulsating red giants in eccentric binary systems, for which masses and radii were constrained. The orbital periods of these systems range from 20 to 440 days. The results of our ongoing radial velocity monitoring programme with the Hermes spectrograph reveal an eccentricity range of e = 0.2 to 0.76. As a case study we present a detailed analysis of KIC 5006817, whose rich oscillation spectrum allows for detailed seismic analysis. From seismology we constrain the rotational period of the envelope to be at least 165 d, which is roughly twice the orbital period. The stellar core rotates 13 times faster than the surface. From the spectrum and radial velocities we expect that the Doppler beaming signal should have a maximum amplitude of 300 ppm in the light curve. Fixing the mass and radius to the asteroseismically determined values, we find from our binary modelling a value of the gravity darkening exponent that is significantly larger than expected. Through binary modelling, we determine the mass of the secondary component to be 0.29 ± 0.03 M . Conclusions. For KIC 5006817 we exclude pseudo-synchronous rotation of the red giant with the orbit. The comparison of the results from seismology and modelling of the light curve shows a possible alignment of the rotational and orbital axis at the 2σ level. Red giant eccentric systems could be progenitors of cataclysmic variables and hot subdwarf B stars.

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Section: Fig 1 Five Examples Ofmentioning

confidence: 99%

Pulsating red giant stars in eccentric binary systems discovered fromKeplerspace-based photometry

Beck

Hambleton

Vos

et al. 2014

A&A

Self Cite

136

151

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“…The early 1990s saw the first attempts to measure solar-like oscillations in giants, which all used photometry (e.g. Gilliland et al 1993 and references therein), but it took a decade before the first firm detection was achieved (Frandsen et al 2002) thanks to newly developed high-precision spectrographs built to find exoplanets. Even after detections of oscillations in about a dozen stars from both ground (Barban et al 2004;De Ridder et al 2006) and early space missions (Buzasi et al 2000, Retter et al 2003, Barban et al 2007, Gilliland 2008), it was not clear which oscillations modes where present and how useful they would be for seismic inferences.…”

Section: Variable Starsmentioning

confidence: 99%

“…Over the past 10-15 years the study of solar-like variables has made tremendous progress, with first confirmations of such oscillations in stars other then the Sun from ground-based spectroscopy for η Bootis (G0IV, Kjeldsen et al 2003), α Cen A (G2V, Butler et al 2004) and B (K1V, Carrier & Bourban 2003), Procyon (F5IV, Eggenberger et al 2004) and ξ Hydrae (G7III, Frandsen et al 2002). Ground-based multi-side spectroscopic campaigns such as the ones for Ophiuchi (G9.…”

Section: Solar-like Variablesmentioning

confidence: 99%

Triennial Report (2012-2015): The Legacy Issue

Pollard¹,

Jeffery²,

Handler³

et al. 2015

Proc. IAU

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“…The short-period variations are, very probably, the result of stellar pulsations (e.g. : Frandsen et al 2002;Hekker et al 2006). The long-term variations are explained by three main phenomena: the presence of an orbiting companion, rotational modulation of surface features and longperiod, non-radial oscillation modes.…”

Section: Line Bisector and Activity Analysismentioning

confidence: 99%

A planet around the evolved intermediate-mass star HD 110014

Medeiros¹,

Setiawan

Hatzes

et al. 2009

A&A

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Context. We found evidence for a sub-stellar companion around the K giant star HD 110014. This cool evolved star, with a spectral type K2III and an estimated mass between 1.9 and 2.4 M , is slightly metal rich with [Fe/H] = 0.19 and a rotational velocity V sin i = 2.0 km s −1 . Aims. To search for extrasolar planets around intermediate-mass stars and to improve our knowledge of the nature of radial velocity variations shown by G and K giant stars. Methods. Based on radial velocity analysis, we found evidence for a substellar companion with a planetary mass and long orbital period. The Radial velocity variation of HD 110014 has been monitored from 2000 until 2007 with FEROS at 1.5 m ESO and at the 2.2 m MPG/ESO, HARPS at the 3.6 m ESO and Coralie at 1.2 m Leonard Euler swiss telescopes in La Silla observatory. The radial velocities were computed by using a cross-correlation technique. Line bisector, Hipparcos photometry and chromospheric lines were analyzed to exclude other root-causes for the radial velocity variability. Results. We report the presence of an extrasolar planet around the giant star HD 110014, with an orbital period of 835.48 ± 6.04 days. A Keplerian orbit, with an eccentricity e = 0.462 ± 0.069, yields a minimum mass M sin i = 11.09 M Jup . The analysis of the residuals shows evidence for a second RV variability with a period of 130 days and an amplitude of ±100 ms −1 . Its nature is not completely clear, but a second planet is a possible explanation.

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Detection of Solar-like oscillations in the G7 giant star ξ Hya

Cited by 181 publications

References 12 publications

Pulsating red giant stars in eccentric binary systems discovered fromKeplerspace-based photometry

Pulsating red giant stars in eccentric binary systems discovered fromKeplerspace-based photometry

Triennial Report (2012-2015): The Legacy Issue

A planet around the evolved intermediate-mass star HD 110014

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