J/ApJ/687/1264 Age estimation for solar-type dwarfs (Mamajek+, 2008)
Improved age estimation for solar-type dwarfs using activity-rotation
diagnostics.
Mamajek E.E., Hillenbrand L.A.
<Astrophys. J., 687, 1264-1293 (2008)>
=2008ApJ...687.1264M 2008ApJ...687.1264M
ADC_Keywords: Stars, G-type ; Photometry ; Stars, ages
Keywords: stars: activity - stars: chromospheres - stars: coronae -
stars: fundamental parameters - stars: rotation - X-rays: stars
Abstract:
While the strong anticorrelation between chromospheric activity and
age has led to the common use of the CaII H and K emission index
(R'HK=LHK/Lbol) as an empirical age estimator for solar-type
dwarfs, existing activity-age relations produce implausible ages at
both high and low activity levels. We have compiled R'HK, data from
the literature for young stellar clusters, richly populating for the
first time the young end of the activity-age relation. Combining the
cluster activity data with modern cluster age estimates and analyzing
the color dependence of the chromospheric activity age index, we
derive an improved activity-age calibration for F7-K2 dwarfs
(0.5<B-V<0.9mag). We also present a more fundamentally motivated
activity-age calibration that relies on conversion of R'HK values
through the Rossby number to rotation periods and then makes use of
improved gyrochronology relations.
Description:
We have collected R'HK indices derived from S-values in the
tradition of the Mount Wilson HK project. The adopted solar data
are: (B-V)0=0.65mag, Age=4.57Gyr, logR'HK=-4.906
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 57 21 logR'HK for color-separated solar-type
dwarf binaries
table3.dat 58 14 logR'HK for near-identical solar-type
dwarf binaries
table4.dat 57 5 Field binaries with rotation periods
table5.dat 108 274 Members of stellar aggregates with logR'HK
measurements
table8.dat 32 23 Old solar-type dwarfs from Valenti et al. (2005,
Cat. J/ApJS/159/141) with age uncertainties of <20%
table12.dat 47 17 Activity-gyro ages for solar-type binaries
table13.dat 110 103 Activity ages for the solar-type dwarfs within 16pc
refs.dat 185 64 References and notes
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Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- StarA Name of primary
12- 21 A10 --- StarB Name of secondary
24- 27 F4.2 mag B-V.A B-V colour index for A component
29- 32 F4.2 mag B-V.B B-V colour index for B component
34- 38 F5.2 --- logR'HKA R'HK index for A component
40- 44 F5.2 --- logR'HKB R'HK index for B component
46- 58 A13 --- Ref References, in refs.dat file (the '*' indicates
values converted to logR'HK by the author
following Noyes et al. (1984ApJ...279..763N 1984ApJ...279..763N))
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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- 10 A10 --- StarA Name of primary
12- 21 A10 --- StarB Name of secondary
23- 26 F4.2 mag B-V.A B-V colour index for A component (1)
28- 31 F4.2 mag B-V.B B-V colour index for B component
33- 37 F5.2 d Per.A Period of A component
39- 43 F5.2 d Per.B Period of B component
45- 57 A13 --- Ref References, in refs.dat file
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Note (1): The period for HD 128620 (alpha Cen A) is a mean (25.6days) from
values given by E. Guinan (2008, priv. com.; 22±3days) and Hallam et
al. (1991ApJ...372..610H 1991ApJ...372..610H; 28.8±2.5days) and is consistent within the
constraints from vsini and p-mode rotational splitting (Fletcher et
al. 2006MNRAS.371..935F 2006MNRAS.371..935F; Bazot et al. 2007A&A...470..295B 2007A&A...470..295B).
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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- 17 A17 --- Name Name
18- 40 A23 --- SName Simbad Name
42- 51 A10 --- OName HD name
53- 56 F4.2 mag B-V ? B-V colour index
58- 59 I2 --- r_B-V ? Reference for B-V, in refs.dat file
61- 64 F4.2 mag E(B-V) Interstellar reddening
66- 71 A6 --- r_E(B-V) Reference for E(B-V), in refs.dat file
74- 77 F4.2 mag (B-V)0 Intrinsic B-V colour index
79- 84 A6 --- r_(B-V)0 Reference for (B-V)0, in refs.dat file
87- 91 F5.2 --- logR'HK R'HK index
93- 95 I3 --- o_logR'HK ? Number of measurements
97- 98 I2 --- r_logR'HK Reference for logR'HK, in refs.dat file
100-108 A9 --- Group Group name (1)
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Note (1): the groups are (from table6 of paper):
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Group Age log RHK 68% N* Usual name
Name Myr median
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US 5 -4.05±0.03 0.13 9 Upper Sco association
beta Pic 12 -4.03±0.13 0.23 6 β Pic association
UCL 16 -4.04±0.01 0.07 10 Upper Cen-Lup and Lower Cen-Cru
Tuc 30 -4.16±0.13 0.16 8 Tuc-Hor association
alpha Per 85 -4.16±0.08 0.27 13 α Per cluster
Pleiades 130 -4.33±0.04 0.24 56 Pleiades cluster
UMa 500 -4.48±0.03 0.09 17 UMa Group
Hyades 625 -4.47±0.01 0.09 87 Hyades cluster
M67 4000 -4.84±0.01 0.11 76 M67 open cluster
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD number (Cat. III/135)
8- 12 F5.3 mag B-V B-V color from Perryman et al.
(HIP, 1997, Cat. I/239)
14- 17 F4.1 Gyr tau Isochronal age (1)
19- 23 F5.2 --- logR'HK R'HK Chromospheric activity
25- 26 I2 --- r_logR'HK Reference for logR'HK, in refs.dat file
28- 32 F5.2 mag DVMAG Difference between stellar absolute magnitude
and that for an MS star of the same B-V color
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Note (1): from Valenti et al. (2005, Cat. J/ApJS/159/141>), uncertainties <20%.
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Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- StarA Name of primary
14- 23 A10 --- StarB Name of secondary
27- 30 F4.2 [yr] logtA Activity-gyro age for component A
32- 36 F5.2 [yr] logtB Activity-gyro age for component B
38- 41 F4.2 [yr] logt Mean gyro age for the system
43- 46 F4.2 [yr] e_logt rms uncertainty on logt
47 A1 --- n_StarA [a] Note for HD 137763 (1)
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Note (1): a: HD 137763 is a pathological case discussed in footnote 10.
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Byte-by-byte Description of file: table13.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD number (Cat. III/135)
8- 13 I6 --- HIP HIP number (Cat. I/311)
15- 21 A7 --- GJ Nearby Star Catalog designation (Cat. V/70)
23- 33 A11 --- OName Other name
35- 40 F6.2 mas plx Parallax
42- 45 F4.2 mas e_plx rms uncertainty on plx
47- 51 F5.3 mag B-V B-V colour index
53 I1 --- r_B-V Reference for B-V, in refs.dat file
55- 60 F6.3 --- logR'HK R'HK index
62- 63 I2 --- r_logR'HK Reference for logR'HK, in refs.dat file
65- 69 F5.2 mag Vmag V magnitude
71- 74 F4.2 mag VMAG Absolute V magnitude
76- 80 F5.2 mag DVMAG Difference between stellar absolute magnitude
and that for an MS star of the same B-V color
82- 96 A15 --- SpType MK spectral type
98- 99 I2 --- r_SpType Reference for SpType, in refs.dat file
101 A1 --- l_tau1 Limit flag on tau1
102-104 F3.1 Gyr tau1 Age from using the revised activity-age
relation
106 A1 --- l_tau2 Limit flag on tau2
107-110 F4.1 Gyr tau2 Age inferred from converting the chromospheric
activity levels to a rotation period via the
Rossby number and then converting the
rotation period to an age using the revised
gyro relation
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode BibCode
24- 44 A21 --- Aut Author's name
47-185 A139 --- Com Comments
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 04-May-2010