A CLASS OF ECCENTRIC BINARIES WITH DYNAMIC TIDAL DISTORTIONS DISCOVERED WITH<i>KEPLER</i>

Thompson, Susan E.; Everett, Mark E.; Mullally, Fergal; Barclay, Thomas; Howell, Steve B.; Still, M.; Rowe, Jason F.; Christiansen, Jessie L.; Kurtz, D. W.; Hambleton, Kelly; Twicken, Joseph D.; Ibrahim, Khadeejah A.; Clarke, Bruce

doi:10.1088/0004-637x/753/1/86

Cited by 223 publications

(230 citation statements)

References 28 publications

(45 reference statements)

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“…19 depicts the eccentricities of the red giant heartbeat stars on the lower RGB found with Kepler from our sample with the eccentricities of those close to the tip of the RGB (Nicholls & Wood 2012). The majority of the systems in Table 1 for which we have RV data have eccentricities between 0.23 < e < 0.5, which is compatible with the range of eccentricities reported by Thompson et al (2012) for their objects. Also, the 4 stars with periods shorter than 30 d belong to the least eccentric in our sample.…”

Section: Comparison To Other Known Red Giant Stars In Eccentric Binarsupporting

confidence: 81%

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

Beck

Hambleton

Vos

et al. 2014

A&A

132

150

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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: Comparison To Other Known Red Giant Stars In Eccentric Binarsupporting

confidence: 81%

“…These so-called Heartbeat stars Thompson et al 2012) are defined as eccentric, detached binary systems that undergo strong gravitational distortions and heating during periastron passage, which are clearly depicted in their light curves (e.g. Fig.…”

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

132

150

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“…The analysis of these observed features led us to the following results: Figure 5 of Thompson et al 2012). (b) The hump duration is shortest for KIC 9474969, in which eccentricity is above two times bigger than those of the other two 'humped' targets (see Table 2 and Figure 15).…”

Section: Tidally Induced Humpsmentioning

confidence: 91%

“…According to this model, the shape of the light increase is one-peaked for i ≤ 30 • but becomes two-peaked with central dip (which depth and width increase with i) for the bigger orbital inclination. Thompson et al (2012) calculated a grid of solutions to the model of Kumar et al (1995) and found that the larger inclinations cause the light curve firstly to increase in brightness and then to decrease (KIC 3547874), or vice versa (KIC 9790355), depending on the angle of periastron, while the bigger eccentricity led to shorter duration of the heartbeat event.…”

Section: Tidally Induced Humpsmentioning

confidence: 99%

Light Curve Solutions of Ten Eccentric Kepler Binaries, Three of them with Tidally Induced Humps

Kjurkchieva

Vasileva

2015

Publ. Astron. Soc. Aust.

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We carried out light curve solutions of ten detached eclipsing eccentric binaries observed by Kepler. The formal errors of the derived parameters from the light curve solutions are below 1%. Our results give indications that the components of the eccentric binaries (especially those with mass ratios below 0.5) do not follow precisely the empirical relations between the stellar parameters derived from the study of circular-orbit binaries. We found the following peculiarities of the targets: (a) the components of KIC 9474969 have almost the same temperatures while their radii and masses differ by a factor around 2.5; (b) KIC 6949550 reveals semi-regular light variations with an amplitude of 0.004 and a period around 7 d which are modulated by long-term variations; (c) KIC 6220470, KIC 11071207, and KIC 9474969 exhibit tidally induced 'hump' around the periastron. These are the targets with the biggest relative radii of our sample. We derived the dependence of the hump amplitude on the relative stellar radii, eccentricity, and mass ratio of eccentric binary consisting of MS stars.

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“…Tidally excited pulsations have been previously observed in several eccentric stellar binaries (Welsh et al 2011;Thompson et al 2012;Beck et al 2014) known as "heartbeat" stars. The characteristic feature of a tidally excited pulsation is that its frequency is an exact integer harmonic of the orbital frequency because it arises from a resonantly forced stellar pulsation mode (Derekas et al 2011;Burkart et al 2012;Fuller & Lai 2012;O'Leary & Burkart 2014;Smullen & Kobulnicky 2015).…”

Section: The Origin Of Hat-p-2's Pulsationsmentioning

confidence: 99%

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

Wit¹,

Lewis

Knutson

et al. 2017

ApJL

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Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet's atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet-star interactions in HAT-P-2ʼs eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μm observations with the Spitzer Space Telescope. The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b's 4.5 μm photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet's orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2ʼs pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

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A CLASS OF ECCENTRIC BINARIES WITH DYNAMIC TIDAL DISTORTIONS DISCOVERED WITHKEPLER

Cited by 223 publications

References 28 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

Light Curve Solutions of Ten Eccentric Kepler Binaries, Three of them with Tidally Induced Humps

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

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