STELLAR AGES AND CONVECTIVE CORES IN FIELD MAIN-SEQUENCE STARS: FIRST ASTEROSEISMIC APPLICATION TO TWO KEPLER TARGETS

Using asteroseismic data and stellar evolution models we obtain the first detection of a convective core in a Kepler field main-sequence star, putting a stringent constraint on the total size of the mixed zone and showing that extra mixing beyond the formal convective boundary exists. In a slightly less massive target the presence of a convective core cannot be conclusively discarded, and thus its remaining main-sequence lifetime is uncertain. Our results reveal that best-fit models found solely by matching individual frequencies of oscillations corrected for surface effects do not always properly reproduce frequency combinations. Moreover, slightly different criteria to define what the best-fit model is can lead to solutions with similar global properties but very different interior structures. We argue that the use of frequency ratios is a more reliable way to obtain accurate stellar parameters, and show that our analysis in field main-sequence stars can yield an overall precision of 1.5%, 4%, and 10% in radius, mass, and age, respectively. We compare our results with those obtained from global oscillation properties, and discuss the possible sources of uncertainties in asteroseismic stellar modeling where further studies are still needed.

[1]  A. Serenelli,et al.  Bayesian analysis of ages, masses and distances to cool stars with non-LTE spectroscopic parameters , 2012, 1212.4497.

[2]  S. Degl'Innocenti,et al.  Cumulative physical uncertainty in modern stellar models - I. The case of low-mass stars , 2012, 1211.0706.

[3]  H. M. Antia,et al.  Acoustic glitches in solar-type stars from Kepler , 2012 .

[4]  M. Pinsonneault,et al.  CHARACTERIZING TWO SOLAR-TYPE KEPLER SUBGIANTS WITH ASTEROSEISMOLOGY: KIC 10920273 AND KIC 11395018 , 2012, 1211.6650.

[5]  J. De Ridder,et al.  FUNDAMENTAL PROPERTIES OF STARS USING ASTEROSEISMOLOGY FROM KEPLER AND CoRoT AND INTERFEROMETRY FROM THE CHARA ARRAY , 2012, 1210.0012.

[6]  P. Tenenbaum,et al.  VERIFYING ASTEROSEISMICALLY DETERMINED PARAMETERS OF KEPLER STARS USING HIPPARCOS PARALLAXES: SELF-CONSISTENT STELLAR PROPERTIES AND DISTANCES , 2012, 1208.6294.

[7]  Yveline Lebreton,et al.  Seismic signature of envelope penetrative convection: the CoRoT star HD 52265 , 2012, 1207.6957.

[8]  John C. Geary,et al.  Kepler-36: A Pair of Planets with Neighboring Orbits and Dissimilar Densities , 2012, Science.

[9]  P. Quirion,et al.  Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets , 2012 .

[10]  T. Appourchaux,et al.  Oscillation mode frequencies of 61 main-sequence and subgiant stars observed by Kepler , 2012, 1204.3147.

[11]  T. Appourchaux,et al.  A UNIFORM ASTEROSEISMIC ANALYSIS OF 22 SOLAR-TYPE STARS OBSERVED BY KEPLER , 2012, 1202.2844.

[12]  D. Guenther,et al.  TOWARD A NEW KIND OF ASTEROSEISMIC GRID FITTING , 2012, 1202.2330.

[13]  S. D. Kawaler,et al.  University of Birmingham Asteroseismology of the solar analogs 16 Cyg A and B from Kepler observations , 2012 .

[14]  William J. Chaplin,et al.  EFFECT OF UNCERTAINTIES IN STELLAR MODEL PARAMETERS ON ESTIMATED MASSES AND RADII OF SINGLE STARS , 2011, 1111.6976.

[15]  India.,et al.  Fundamental properties of five Kepler stars using global asteroseismic quantities and ground-based observations , 2011, 1111.4615.

[16]  A. Miglio,et al.  Assessing the accuracy of the surface gravity determination in late-type stars with solar-like pulsators , 2011, 1110.2036.

[17]  J. De Ridder,et al.  TESTING SCALING RELATIONS FOR SOLAR-LIKE OSCILLATIONS FROM THE MAIN SEQUENCE TO RED GIANTS USING KEPLER DATA , 2011, 1109.3460.

[18]  Hans Kjeldsen,et al.  CALCULATING ASTEROSEISMIC DIAGRAMS FOR SOLAR-LIKE OSCILLATIONS , 2011, 1109.3455.

[19]  S. Deheuvels,et al.  Constraints on the structure of the core of subgiants via mixed modes: the case of HD 49385 , 2011, 1109.1191.

[20]  P. Gaulme,et al.  Asteroseismology from multi-month Kepler photometry: the evolved Sun-like stars KIC 10273246 and KIC 10920273 , 2011, 1108.3807.

[21]  P. Gaulme,et al.  CONSTRUCTING A ONE-SOLAR-MASS EVOLUTIONARY SEQUENCE USING ASTEROSEISMIC DATA FROM KEPLER , 2011, 1108.2031.

[22]  T. Bedding.  Solar-like Oscillations: An Observational Perspective , 2011, 1107.1723.

[23]  F. Baudin,et al.  Accurate p-mode measurements of the G0V metal-rich CoRoT target HD 52265 , 2011, 1105.3551.

[24]  P. Gaulme,et al.  Global asteroseismic properties of solar-like oscillations observed by Kepler: a comparison of complementary analysis methods , 2011, 1105.0571.

[25]  S. D. Kawaler,et al.  Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission , 2011, Science.

[26]  B. Mosser,et al.  The underlying physical meaning of the νmax νc relation , 2011, 1104.0630.

[27]  L. Casagrande,et al.  New constraints on the chemical evolution of the solar neighbourhood and galactic disc(s) - improved astrophysical parameters for the Geneva-Copenhagen Survey , 2011, 1103.4651.

[28]  R. Gilliland,et al.  Preparation of Kepler lightcurves for asteroseismic analyses , 2011, 1103.0382.

[29]  V. S. Aguirre,et al.  Constraining mixing processes in stellar cores using asteroseismology - Impact of semiconvection in low-mass stars , 2011, 1102.0779.

[30]  Timothy M. Brown,et al.  KEPLER INPUT CATALOG: PHOTOMETRIC CALIBRATION AND STELLAR CLASSIFICATION , 2011, 1102.0342.

[31]  William J. Chaplin,et al.  AN IN-DEPTH STUDY OF GRID-BASED ASTEROSEISMIC ANALYSIS , 2010, 1009.3018.

[32]  M. Cunha,et al.  Probing tiny convective cores with the acoustic modes of lowest degree , 2010, 1008.1299.

[33]  T. Bedding,et al.  Asteroseismic modelling of the solar-type subgiant star β Hydri , 2010, 1012.3872.

[34]  S. Dreizler,et al.  A PRECISE ASTEROSEISMIC AGE AND RADIUS FOR THE EVOLVED SUN-LIKE STAR KIC 11026764 , 2010, 1010.4329.

[35]  J. Christensen-Dalsgaard,et al.  AUTOMATIC DETERMINATION OF STELLAR PARAMETERS VIA ASTEROSEISMOLOGY OF STOCHASTICALLY OSCILLATING STARS: COMPARISON WITH DIRECT MEASUREMENTS , 2010, 1009.5131.

[36]  G. Torres.  ON THE USE OF EMPIRICAL BOLOMETRIC CORRECTIONS FOR STARS , 2010, 1008.3913.

[37]  J. Christensen-Dalsgaard,et al.  Seismic signatures of stellar cores of solar-like pulsators: dependence on mass and age , 2010, 1008.2630.

[38]  I. Roxburgh.  Asteroseismology of solar and stellar models , 2010 .

[39]  A. Weiss,et al.  ON USING THE COLOR–MAGNITUDE DIAGRAM MORPHOLOGY OF M67 TO TEST SOLAR ABUNDANCES , 2010, 1004.3308.

[40]  C. Flynn,et al.  Revisiting Delta Y/Delta Z from multiple main sequences in Globular Clusters: insight from nearby stars , 2010, 1004.1539.

[41]  L. Casagrande,et al.  An absolutely calibrated T eff scale from the infrared flux method. Dwarfs and subgiants , 2010, 1001.3142.

[42]  G. Steigman.  Primordial helium and the cosmic background radiation , 2010, 1002.3604.

[43]  P. Morel,et al.  Survival of a convective core in low-mass solar-like pulsator HD 203608 , 2010, 1002.3461.

[44]  J. Christensen-Dalsgaard,et al.  Prospects for asteroseismology , 2009, 0911.4629.

[45]  William J. Chaplin,et al.  DETERMINATION OF STELLAR RADII FROM ASTEROSEISMIC DATA , 2009, 0909.0506.

[46]  D. A. Caldwell,et al.  INITIAL CHARACTERISTICS OF KEPLER SHORT CADENCE DATA , 2009, 1001.0142.

[47]  P. Gaulme,et al.  Solar-like oscillations in HD 181420: data analysis of 156 days of CoRoT data , 2009 .

[48]  J. Ferguson,et al.  NEW SOLAR COMPOSITION: THE PROBLEM WITH SOLAR MODELS REVISITED , 2009, 0909.2668.

[49]  M. Asplund,et al.  The chemical composition of the Sun , 2009, 0909.0948.

[50]  J. Ridder,et al.  Probing populations of red giants in the galactic disk with CoRoT , 2009, 0908.0210.

[51]  T. Appourchaux,et al.  RADIUS DETERMINATION OF SOLAR-TYPE STARS USING ASTEROSEISMOLOGY: WHAT TO EXPECT FROM THE KEPLER MISSION , 2009, 0906.0766.

[52]  S. Cassisi.  Stellar Evolutionary Models: current uncertainties , 2009 .

[53]  J. Christensen-Dalsgaard,et al.  A STELLAR MODEL-FITTING PIPELINE FOR ASTEROSEISMIC DATA FROM THE KEPLER MISSION , 2009, 0903.0616.

[54]  R. Peletier.  PROBING STELLAR POPULATIONS OUT TO THE DISTANT UNIVERSE , 2009 .

[55]  Ian W. Roxburgh,et al.  Small separations and phase shift differences of ℓ=0,1 p-modes , 2009 .

[56]  A. Weiss,et al.  GARSTEC—the Garching Stellar Evolution Code , 2008 .

[57]  Hans Kjeldsen,et al.  TO APPEAR IN APJ LETTERS Preprint typeset using LATEX style emulateapj v. 10/09/06 CORRECTING STELLAR OSCILLATION FREQUENCIES FOR NEAR-SURFACE EFFECTS , 2022 .

[58]  D. Queloz,et al.  Spectroscopic parameters for 451 stars in the HARPS GTO planet search program - Stellar [Fe/H] and the frequency of exo-Neptunes , 2008, 0805.4826.

[59]  P. Morel,et al.  Thorough analysis of input physics in CESAM and CLÉS codes , 2008, 0804.2144.

[60]  P. Morel,et al.  CESAM: a free code for stellar evolution calculations , 2008, 0801.2019.

[61]  J. Christensen-Dalsgaard,et al.  CoRoT/ESTA–TASK 1 and TASK 3 comparison of the internal structure and seismic properties of representative stellar models , 2008, 0801.0928.

[62]  A. Miglio,et al.  The Liège Oscillation code , 2007, 0712.3474.

[63]  J. Christensen-Dalsgaard,et al.  Inter-comparison of the g-, f- and p-modes calculated using different oscillation codes for a given stellar model , 2007, 0711.2587.

[64]  Jørgen Christensen-Dalsgaard,et al.  ASTEC—the Aarhus STellar Evolution Code , 2007, 0710.3114.

[65]  David R. Soderblom,et al.  The Ages of Stars , 2007, 1003.6074.

[66]  G. Steigman.  Primordial Nucleosynthesis in the Precision Cosmology Era , 2007, 0712.1100.

[67]  D. B. Guenther,et al.  YREC: the Yale rotating stellar evolution code , 2007, 0710.4003.

[68]  Jørgen Christensen-Dalsgaard,et al.  ADIPLS—the Aarhus adiabatic oscillation package , 2007, 0710.3106.

[69]  F. V. Leeuwen.  Validation of the new Hipparcos reduction , 2007, 0708.1752.

[70]  J. Ferguson,et al.  A Constraint on Z☉ from Fits of Isochrones to the Color-Magnitude Diagram of M67 , 2007, 0708.1172.

[71]  Acoustic wave reflection by stellar cores: can it be seen in the autocorrelation function of p-mode measurements? , 2007 .

[72]  T. Metcalfe,et al.  Asteroseismic Signatures of Small Convective Cores , 2007, 0705.3009.

[73]  Porto,et al.  A new code for automatic determination of equivalent widths: Automatic Routine for line Equivalent widths in stellar Spectra (ARES) , 2007, astro-ph/0703696.

[74]  R. Gilliland,et al.  Asteroseismology with the Kepler mission , 2007, astro-ph/0701323.

[75]  E. Ford,et al.  Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog , 2006, astro-ph/0607235.

[76]  S. Basu,et al.  Asteroseismic diagnostics of stellar convective cores , 2005, astro-ph/0608331.

[77]  A. Montalbán,et al.  Constraining fundamental stellar parameters using seismology. Application to α Centauri AB , 2005, astro-ph/0505537.

[78]  David R. Alexander,et al.  Low-Temperature Opacities , 2005, astro-ph/0502045.

[79]  Michael Thompson,et al.  The use of frequency-separation ratios for asteroseismology , 2005 .

[80]  Rafael A. García,et al.  Seismic extraction of the convective extent in solar-like stars The observational point of view , 2004 .

[81]  S. Cassisi,et al.  A Large Stellar Evolution Database for Population Synthesis Studies. I. Scaled Solar Models and Isochrones , 2004, astro-ph/0405193.

[82]  Ian W. Roxburgh,et al.  The ratio of small to large separations of acoustic oscillations as a diagnostic of the interior of solar-like stars , 2003 .

[83]  T. Metcalfe,et al.  The core/envelope symmetry in pulsating stars , 2003, astro-ph/0305601.

[84]  S. Cassisi,et al.  The Initial Helium Content of Galactic Globular Cluster Stars from the R-Parameter: Comparison with the Cosmic Microwave Background Constraint , 2003, astro-ph/0301378.

[85]  Forrest J. Rogers,et al.  Updated and Expanded OPAL Equation-of-State Tables: Implications for Helioseismology , 2002 .

[86]  H. M. Antia,et al.  Seismic study of stellar convective cores , 2001, astro-ph/0107576.

[87]  G. Meynet,et al.  THE EVOLUTION OF ROTATING STARS , 2000, astro-ph/0004204.

[88]  William J. Chaplin,et al.  Skew-symmetric solar p modes in low-l BiSON data , 1999 .

[89]  E. Henley,et al.  Solar fusion cross sections , 1998, astro-ph/9805121.

[90]  P. Morel.  CESAM: A code for stellar evolution calculations , 1997 .

[91]  A. Weiss,et al.  Erratum: "The Age of the Oldest Globular Clusters" (ApJ, 479, 665 [1997]) , 1997 .

[92]  P. Flower,et al.  Transformations from Theoretical Hertzsprung-Russell Diagrams to Color-Magnitude Diagrams: Effective Temperatures, B-V Colors, and Bolometric Corrections , 1996 .

[93]  I. Goldman,et al.  Stellar Turbulent Convection: A Self-consistent Model , 1996 .

[94]  Forrest J. Rogers,et al.  Updated Opal Opacities , 1996 .

[95]  S. M. Chitre,et al.  The Current State of Solar Modeling , 1996, Science.

[96]  Forrest J. Rogers,et al.  Opal equation-of-state tables for astrophysical applications , 1996 .

[97]  P. Demarque,et al.  The Gap in the Color-Magnitude Diagram of NGC 2420: A Test of Convective Overshoot and Cluster Age , 1994 .

[98]  Ian W. Roxburgh,et al.  The seismology of stellar cores: a simple theoretical description of the small frequency separations. , 1994 .

[99]  I. Roxburgh,et al.  Seismology of the solar envelope: the base of the convective zone as seen in the phase shift of acoustic waves , 1994 .

[100]  A. Loeb,et al.  Element Diffusion in the Solar Interior , 1993, astro-ph/9304005.

[101]  F. Pérez Hernández,et al.  The phase function for stellar acoustic oscillations – I. Theory , 1992 .

[102]  N. Balmforth.  Solar pulsational stability – III. Acoustical excitation by turbulent convection , 1992 .

[103]  A. Bressan,et al.  New Developments in Understanding the HR Diagram , 1992 .

[104]  Timothy M. Brown,et al.  Detection of possible p-mode oscillations on Procyon , 1991 .

[105]  Brian H. Houston,et al.  Fiber-optic air-backed hydrophone transduction mechanisms , 1991 .

[106]  Achim Weiss,et al.  Stellar Structure and Evolution , 1990 .

[107]  J. Christensen-Dalsgaard,et al.  Solar oscillation frequencies and the equation of state , 1988, Nature.

[108]  Dimitri Mihalas,et al.  The equation of state for stellar envelopes. I - An occupation probability formalism for the truncation of internal partition functions , 1988 .

[109]  D. VandenBerg,et al.  Constraints from stellar models on mixing as a viable explanation of abundance anomalies in globular clusters , 1988 .

[110]  Jørgen Christensen-Dalsgaard,et al.  Advances in Helio- and Asteroseismology , 1988 .

[111]  Douglas Gough.  Seismological measurement of stellar ages , 1987, Nature.

[112]  R. K. Ulrich,et al.  Determination of stellar ages from asteroseismology , 1986 .

[113]  D. VandenBerg,et al.  Theoretical isochrones for globular clusters with predicted BVRI and Stromgren photometry. , 1985 .

[114]  Eugene H. Avrett,et al.  Structure of the solar chromosphere. III. Models of the EUV brightness components of the quiet sun , 1981 .

[115]  A. Endal,et al.  The Evolution of Rotating Stars. , 1975 .

[116]  David R. Alexander,et al.  Low-Temperature Rosseland Opacities , 1975 .