TY - JOUR

T1 - A seismic and gravitationally bound double star observed by Kepler

T2 - Implication for the presence of a convective core

AU - Appourchaux, T.

AU - Antia, H. M.

AU - Ball, W.

AU - Creevey, O.

AU - Lebreton, Y.

AU - Verma, K.

AU - Vorontsov, S.

AU - Campante, T. L.

AU - Davies, G. R.

AU - Gaulme, P.

AU - Régulo, C.

AU - Horch, E.

AU - Howell, S.

AU - Everett, M.

AU - Ciardi, D.

AU - Fossati, L.

AU - Miglio, A.

AU - Montalbán, J.

AU - Chaplin, W. J.

AU - García, R. A.

AU - Gizon, L.

N1 - Funding Information:
T.A. gratefully acknowledges the financial support of the Centre National d’Etudes Spatiales (CNES) under a PLATO grant. T.L.C., W.J.C., and G.R.D. acknowledge financial support from the UK Science and Technology Facilities Council (STFC). W.B. and L.G. acknowledge support from the Deutsche Forschungsgemeinschaft SFB 963 “Astrophysical Flow Instabilities and Turbulence” (Project A18). L.G. acknowledges research funding from the Center for Space Science, NYU Abu Dhabi Institute, UAE. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation. We are indebted to Ian Roxburgh for extensively commenting on the paper and for his timely contribution. We are grateful to Sébastien Salmon for commenting on an earlier version of the paper. We are also indebted to Georges Herriman for silently accepting to use the name Krazy and Ignatz for these two stars. We are grateful to the anonymous referee for the constructive and useful comments.
Publisher Copyright:
© ESO, 2015.

PY - 2015/10/1

Y1 - 2015/10/1

N2 - Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology. Aims. The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP93511), for which an interferometric orbit has been observed along with asteroseismic measurements. Methods. We used a time series of nearly two years of data for the double star to detect the two oscillation-mode envelopes that appear in the power spectrum. Using a new scaling relation based on luminosity, we derived the radius and mass of each star. We derived the age of each star using two proxies: one based upon the large frequency separation and a new one based upon the small frequency separation. Using stellar modelling, the mode frequencies allowed us to derive the radius, the mass, and the age of each component. In addition, speckle interferometry performed since 2006 has enabled us to recover the orbit of the system and the total mass of the system. Results. From the determination of the orbit, the total mass of the system is 2.34-0.33 +0.45 M⊙. The total seismic mass using scaling relations is 2.47 ± 0.07 M⊙. The seismic age derived using the new proxy based upon the small frequency separation is 3.5 ± 0.3 Gyr. Based on stellar modelling, the mean common age of the system is 2.7-3.9 Gyr. The mean total seismic mass of the system is 2.34-2.53 M⊙ consistent with what we determined independently with the orbit. The stellar models provide the mean radius, mass, and age of the stars as RA = 1.82-1.87R⊙, MA = 1.25-1.39 M⊙, AgeA = 2.6-3.5 Gyr; RB = 1.22-1.25 R⊙, MB = 1.08-1.14 M⊙, AgeB = 3.35-4.21 Gyr. The models provide two sets of values for Star A: [1.25-1.27] M⊙ and [1.34-1.39] M⊙. We detect a convective core in Star A, while Star B does not have any. For the metallicity of the binary system of Z ≈ 0.02, we set the limit between stars having a convective core in the range [1.14-1.25] M⊙.

AB - Context. Solar-like oscillations have been observed by Kepler and CoRoT in many solar-type stars, thereby providing a way to probe stars using asteroseismology. Aims. The derivation of stellar parameters has usually been done with single stars. The aim of the paper is to derive the stellar parameters of a double-star system (HIP93511), for which an interferometric orbit has been observed along with asteroseismic measurements. Methods. We used a time series of nearly two years of data for the double star to detect the two oscillation-mode envelopes that appear in the power spectrum. Using a new scaling relation based on luminosity, we derived the radius and mass of each star. We derived the age of each star using two proxies: one based upon the large frequency separation and a new one based upon the small frequency separation. Using stellar modelling, the mode frequencies allowed us to derive the radius, the mass, and the age of each component. In addition, speckle interferometry performed since 2006 has enabled us to recover the orbit of the system and the total mass of the system. Results. From the determination of the orbit, the total mass of the system is 2.34-0.33 +0.45 M⊙. The total seismic mass using scaling relations is 2.47 ± 0.07 M⊙. The seismic age derived using the new proxy based upon the small frequency separation is 3.5 ± 0.3 Gyr. Based on stellar modelling, the mean common age of the system is 2.7-3.9 Gyr. The mean total seismic mass of the system is 2.34-2.53 M⊙ consistent with what we determined independently with the orbit. The stellar models provide the mean radius, mass, and age of the stars as RA = 1.82-1.87R⊙, MA = 1.25-1.39 M⊙, AgeA = 2.6-3.5 Gyr; RB = 1.22-1.25 R⊙, MB = 1.08-1.14 M⊙, AgeB = 3.35-4.21 Gyr. The models provide two sets of values for Star A: [1.25-1.27] M⊙ and [1.34-1.39] M⊙. We detect a convective core in Star A, while Star B does not have any. For the metallicity of the binary system of Z ≈ 0.02, we set the limit between stars having a convective core in the range [1.14-1.25] M⊙.

KW - asteroseismology

KW - astrometry

KW - binaries: general

KW - stars: evolution

KW - stars: solar-type

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U2 - 10.1051/0004-6361/201526610

DO - 10.1051/0004-6361/201526610

M3 - Article

AN - SCOPUS:84942741254

VL - 582

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A25

ER -