J/ApJ/749/152 Asteroseismic analysis of 22 solar-type stars (Mathur+, 2012)
A uniform asteroseismic analysis of 22 solar-type stars observed by Kepler.
Mathur S., Metcalfe T.S., Woitaszek M., Bruntt H., Verner G.A.,
Christensen-Dalsgaard J., Creevey O.L., Dogan G., Basu S., Karoff C.,
Stello D., Appourchaux T., Campante T.L., Chaplin W.J., Garcia R.A.,
Bedding T.R., Benomar O., Bonanno A., Deheuvels S., Elsworth Y., Gaulme P.,
Guzik J.A., Handberg R., Hekker S., Herzberg W., Monteiro M.J.P.F.G.,
Piau L., Quirion P.-O., Regulo C., Roth M., Salabert D., Serenelli A.,
Thompson M.J., Trampedach R., White T.R., Ballot J., Brandao I.M.,
Molenda-Zakowicz J., Kjeldsen H., Twicken J.D., Uddin K., Wohler B.
<Astrophys. J., 749, 152 (2012)>
=2012ApJ...749..152M 2012ApJ...749..152M
ADC_Keywords: Effective temperatures ; Stars, ages ; Stars, masses ;
Stars, diameters
Keywords: methods: numerical - stars: evolution - stars: interiors
stars: oscillations
Abstract:
Asteroseismology with the Kepler space telescope is providing not only
an improved characterization of exoplanets and their host stars, but
also a new window on stellar structure and evolution for the large
sample of solar-type stars in the field. We perform a uniform analysis
of 22 of the brightest asteroseismic targets with the highest
signal-to-noise ratio observed for 1 month each during the first year
of the mission, and we quantify the precision and relative accuracy of
asteroseismic determinations of the stellar radius, mass, and age that
are possible using various methods. We present the properties of each
star in the sample derived from an automated analysis of the
individual oscillation frequencies and other observational constraints
using the Asteroseismic Modeling Portal (AMP), and we compare them to
the results of model-grid-based methods that fit the global
oscillation properties. We find that fitting the individual
frequencies typically yields asteroseismic radii and masses to ∼1%
precision, and ages to ∼2.5% precision (respectively, 2, 5, and 8
times better than fitting the global oscillation properties). The
absolute level of agreement between the results from different
approaches is also encouraging, with model-grid-based methods yielding
slightly smaller estimates of the radius and mass and slightly older
values for the stellar age relative to AMP, which computes a large
number of dedicated models for each star. The sample of targets for
which this type of analysis is possible will grow as longer data sets
are obtained during the remainder of the mission.
Description:
During the first year of the Kepler mission, a survey was conducted of
nearly 2000 solar-type stars observed for 1 month each with 1 minute
sampling to search for evidence of solar-like oscillations (Chaplin et
al. 2011Sci...332..213C 2011Sci...332..213C; Verner et al. 2011MNRAS.415.3539V 2011MNRAS.415.3539V). Based on
the signal-to-noise ratio of their oscillation modes, we selected a
sample of 22 of the best stars, for which we could extract the
individual frequencies and which covered a broad range of properties
in the H-R diagram. Before analyzing the data, the light curves were
processed following Garcia et al. (2011MNRAS.414L...6G 2011MNRAS.414L...6G) to remove
jumps, outliers, and other instrumental effects. The raw light curves
(Jenkins et al. 2010ApJ...713L..87J 2010ApJ...713L..87J) were then subjected to a
high-pass filter with a cutoff frequency at 1 cycle per day.
The atmospheric parameters Teff, log g, and [Fe/H] were determined by
analyzing high-quality spectra acquired from two service observing
programs during the summer of 2010 using the ESPADONs spectrograph at
the Canada-France-Hawaii Telescope and the NARVAL spectrograph at the
Bernard Lyot telescope. The spectra have a resolution of 80000 and a
typical signal-to-noise ratio in the continuum of 200-300.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 45 855 Observed and model frequencies
table3.dat 78 22 *Non-seismic constraints adopted for the modeling
and the corresponding model properties from AMP
table4.dat 87 66 Global oscillation properties from 1 month of
data and model-grid-based results
table5.dat 104 22 *Properties of the optimal models and surface
correction from AMP results
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Note on table3.dat, table5.dat: AMP = Asteroseismic Modeling Portal, see
http://amp.ucar.edu/
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
J/ApJS/199/30 : Effective temperature scale for KIC stars (Pinsonneault+, 2012)
J/ApJ/746/16 : Modelling the convection zone (van Saders+, 2012)
J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)
J/A+A/531/A124 : Visibilities of stellar oscillation modes (Ballot+, 2011)
J/ApJ/729/L10 : KIC stars properties in NGC 6791 and NGC 6819 (Basu+, 2011)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/ApJ/718/L97 : Early asteroseismic results from Kepler (Van Grootel+, 2010)
J/ApJ/469/355 : Teff, B-V and BC relation (Flower, 1996)
http://amp.ucar.edu/ : The Asteroseismic Modeling Portal (AMP) Web site
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [KIC]
5- 12 I8 --- KIC KIC identification number (Cat. V/133)
14 I1 --- l [0/2] The degree l of the mode
16- 17 I2 --- n [7/27] Radial order n from the optimal model
19- 25 F7.2 uHz nuobs [649/3889]? Observed frequency νobs
27- 30 F4.2 uHz e_nuobs [0.08/3.7]? Uncertainty in nuobs
32- 38 F7.2 uHz nucor [428/4189] Corrected frequency νcor (1)
40- 45 F6.2 uHz anu [-18.7/0] Size of surface correction from Eq.3
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Note (1): From Asteroseismic Modeling Portal (AMP) after applying
the surface correction.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC KIC identification number (Cat. V/133)
10- 13 I4 K Teff [5340/6300] Effective temperature (1)
15- 17 I3 K e_Teff [52/125] Teff uncertainty (4)
19 A1 --- r_Teff [b] Origin of Teff (5)
21- 24 I4 K T*eff [5268/6314] Effective temperature from AMP (2)
26- 29 F4.2 [cm/s2] logg [3.9/4.7]? Surface gravity (1)
31- 34 F4.2 [cm/s2] e_logg [0.07/0.2]? logg uncertainty (4)
36- 39 F4.2 [cm/s2] logg* [3.8/4.5] Surface gravity from AMP (2)
41- 45 F5.2 [Sun] [Fe/H] [-1.2/0.4]? Metallicity (1)
47- 50 F4.2 [Sun] e_[Fe/H] [0.07/0.5]? [Fe/H] uncertainty (4)
52 A1 --- r_[Fe/H] [c] Origin of [Fe/H] (5)
54- 58 F5.2 [Sun] [Fe/H]* [-0.8/0.4] Metallicity from AMP (2)
60- 63 F4.2 [Lsun] Lum [0.6/5]? Luminosity (1)
65- 68 F4.2 [Lsun] e_Lum [0.02/1.5]? L/Lsun uncertainty (4)
70- 73 F4.2 [Lsun] Lum* [0.6/6] Luminosity from AMP (2)
75- 78 F4.1 --- chi2sp [0/16] Normalized χ2spec (3)
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Note (1): Teff, logg, [Fe/H], and L/L☉ are, respectively, the values
of effective temperature, surface gravity, metallicity, and luminosity
adopted for modeling as derived in Section 2.2
Note (2): effective temperature, surface gravity, metallicity, and
luminosity adopted from the optimal model from Asteroseismic Modeling
Portal (AMP).
Note (3): The normalized χ2spec (for the spectroscopic parameters)
is calculated from Equation (5).
Note (4): Quoted errors include the statistical and systematic
uncertainties combined in quadrature.
Note (5): Flag as follows:
b = From Pinsonneault et al. (2012, Cat. J/ApJS/199/30).
c = From Brown et al. (2011, Cat. J/AJ/142/112).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC KIC identification number (Cat. V/133)
10- 13 A4 --- Qr Observation Quarter (1)
15- 18 I4 uHz numax [910/3545] Frequency of maximum power
20- 22 I3 uHz e_numax [10/140] numax uncertainty
24- 29 F6.2 uHz Dnu [50/149] Mean large frequency separation (2)
31- 34 F4.2 uHz e_Dnu [0.1/0.6] Dnu uncertainty
36- 41 A6 --- Meth Method used to determine R, M and t (3)
43- 46 F4.2 Rsun R [0.9/2.1]? Radius
48- 51 F4.2 Rsun E_R [0/0.1]? Positive error on R
53- 56 F4.2 Rsun e_R [0/0.1]? Negative error on R
58- 61 F4.2 Msun M [0.7/1.5]? Mass
63- 66 F4.2 Msun E_M [0/0.3]? Positive error on M
68- 71 F4.2 Msun e_M [0/0.2]? Negative error on M
73- 77 F5.2 Gyr t [1/14]? Age
79- 82 F4.2 Gyr E_t [0.1/2.3]? Positive error on t
84- 87 F4.2 Gyr e_t [0/5.2]? Negative error on t
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Note (1): Kepler data are collected by quarters that lasted 3 months except
for the first quarter, which lasted 1 month (referred as Q1). One
month of the other quarters are denoted as Q2.1 for example to refer
to the first month of the second quarter.
Note (2): Dnu (<Δν>) is the mean large frequency separation
computed as described in Section 2.1.
Note (3): Method as follows:
YB = The YB method uses a variant of the Yale-Birmingham code (Basu et al.
2010ApJ...710.1596B 2010ApJ...710.1596B), as described by Gai et al. (2011ApJ...730...63G 2011ApJ...730...63G).
The method finds the maximum likelihood of the stellar radius, mass, and
age from several grids of models using the values of Dnu, numax, Teff,
and [Fe/H] as input. See section 3.2.
RADIUS = The RADIUS method (Stello et al. 2009ApJ...700.1589S 2009ApJ...700.1589S) uses Teff,
log g, [Fe/H], L, and Dnu to find the optimal model. The method is
based on a large grid of Aarhus STellar Evolution Code (ASTEC;
Christensen-Dalsgaard, 2008Ap&SS.316...13C 2008Ap&SS.316...13C) models using the EFF
equation of state (Eggleton et al. 1973A&A....23..325E 1973A&A....23..325E).
See section 3.1
SEEK = The SEEK method uses a large grid of stellar models computed with
ASTEC. See section 3.3
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- KIC KIC identification number (Cat. V/133)
10- 13 F4.2 Rsun R [0.9/2.1] Star radius
15- 18 F4.2 Rsun e_R [0/0.1] R uncertainty (7)
20- 23 F4.2 Msun M [0.8/1.4] Star mass
25- 28 F4.2 Msun e_M [0/0.03] M uncertainty (7)
30- 34 F5.2 Gyr t [3.1/13.4] Stellar age
36- 39 F4.2 Gyr e_t [0.02/0.4] t uncertainty (7)
41- 46 F6.4 --- Z [0.003/0.05] Star metallicity
48- 53 F6.4 --- e_Z [0.0001/0.003] Z uncertainty (7)
55- 59 F5.3 --- Yi [0.2/0.4] Initial He mass fraction (Yi)
61- 65 F5.3 --- e_Yi [0.001/0.04] Yi uncertainty (7)
67- 70 F4.2 --- alpha [1.6/2.2] Mixing-length parameter α
72- 75 F4.2 --- e_alpha [0.01/0.2] alpha uncertainty (7)
77- 81 F5.3 --- rCZ/R [0/1] Position of the base of the
convection zone (rCZ)
83- 87 F5.3 --- E_rCZ/R [0.001/0.02] Positive error on rCZ/R (7)
89- 93 F5.3 --- e_rCZ/R [0.001/0.03] Negative error on rCZ/R (7)
95- 99 F5.2 uHz a0 [-6.7/-0.9] Size of the surface correction
at νmax (a0) (6)
101-104 F4.1 --- chi2sei [1.1/14.4] Normalized χ2seis (for
asteroseismic constraints) calculated from
equation 4.
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Note (6): The size of the surface correction at νmax (a0) in µHz
for the optimal model from AMP. See section 3.4, equation (3).
Note (7): Quoted errors include only the statistical uncertainties. See
Section 4 for a discussion of the systematics.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 28-Nov-2013