J/A+A/348/897 Ages of main-sequence stars (Lachaume+, 1999)
Age determinations of main-sequence stars: combining different methods.
Lachaume R., Dominik C., Lanz T., Habing H.J.
<Astron. Astrophys. 348, 897 (1999)>
=1999A&A...348..897L 1999A&A...348..897L
ADC_Keywords: Stars, dwarfs ; Stars, ages ; Rotational velocities ;
Space velocities ; Abundances, [Fe/H]
Keywords: stars: activity - stars: chromospheres - stars: evolution -
stars: rotation
Abstract:
We have determined the age of a sample of nearby main-sequence stars
with spectral types B9-K9. We have derived the stellar ages from five
different age estimators: the location in the HR diagram compared to
theoretical isochrones, the rotational velocity, the strength of
chromospheric calcium emission lines, the stellar metallicity, and
their space velocity. New calibrations consistent with recent
theoretical isochrones are provided for the last four indicators. For
hot stars, isochrones are the best indicator, while stellar rotation
is best for cool stars. However, many stars require in fact a
combination of different methods to properly bracket their actual age.
We also discuss the uncertainties involved, in particular those in
using isochrones, and we find that these uncertainties are often
underestimated in the literature.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 54 68 Ages from Bertelli's isochrones
tablea2.dat 47 19 Rotational ages
tablea3.dat 23 34 Calcium ages
tablea4.dat 32 49 Kinetic ages
tablea5.dat 23 81 Metallicity datation
tablea6.dat 38 91 Final ages
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See also:
J/A+A/329/943 : F + G solar neighbourhood stars new ages (Ng+ 1998)
J/MNRAS/298/332 : Chromospheric activity-age relation (Rocha-Pinto+ 1998)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
9- 12 I4 K Teff Effective temperature
14- 18 F5.2 [Sun] [Fe/H] Metallicity
21- 25 F5.3 mag VMAG Absolute V magnitude
27- 31 F5.2 [yr] logLowAge ? Low isochronic age
32- 33 A2 --- n_logLowAge Note on undetermination of logLowAge (1)
35- 39 F5.2 [yr] logMedAge ? Medium isochronic age
40- 41 A2 --- n_logMedAge Note on undetermination of logMedAge (1)
43- 47 F5.2 [yr] logUppAge ? Upper isochronic age
48- 49 A2 --- n_logUppAge Note on undetermination of logUppAge (1)
52- 54 A3 --- Ref Reference (2)
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Note (1): Note on age as follows:
-i = -∞
+i = +∞
! = badly placed on HR diagram: no computation possible.
Note (2): References as follows:
K = Geneva Photometry with calibration from
Kunzli et al. 1997, Cat. J/A+AS/122/51
E = Edvardsson et al. 1993, Cat. J/A+AS/102/603
A = solar value assumed
B = Berthet et al., 1990A&A...236..440B 1990A&A...236..440B
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
9- 12 F4.1 d Per Period of rotation
15- 18 F4.2 mag B-V B-V colour index
20- 24 F5.2 [Sun] [Fe/H] Metallicity
26- 30 F5.2 [yr] LowAge Low rotational age
32- 36 F5.2 [yr] MedAge Medium rotational age
37 A1 --- n_MedAge [*] *: Age overestimated
39- 43 F5.2 [yr] UppAge Upper rotational age
45 A1 --- r_[Fe/H] Reference for [Fe/H] (1)
47 A1 --- r_Per Reference for Per (2)
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Note (1): References for [Fe/H] as follows:
A = Metallicity assumed, taken to be consistent with the age found
E = Edvardsson et al. 1993, Cat. J/A+AS/102/603
K = Geneva photometry with calibration from
Kunzli et al. 1997, Cat. J/A+AS/122/51
Z = Zakhozhaj & Shaparenko 1996, Cat. J/other/KFNT/12.20
Note (2): References for Per as follows:
N = Noyes et al., 1984ApJ...279..763N 1984ApJ...279..763N
B = Baliunas, Sokoloff and Soon, 1996ApJ...457L..99B 1996ApJ...457L..99B
S = Saar & Osten, 1997MNRAS.284..803S 1997MNRAS.284..803S
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Byte-by-byte Description of file: tablea3.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
8- 13 F6.3 --- logR'HK Strength of chromospheric calcium emission
lines (1)
16 A1 --- r_logR'HK Reference for logR'HK (2)
20- 23 F4.2 [yr] logAge Age
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Note (1): R'HK is the ratio which measures the emission in the
calcium H and K bands relative to the total stellar flux.
Note (2): References as follows:
B = Baliunas, Sokoloff & Soon, 1996ApJ...457L..99B 1996ApJ...457L..99B
H = Henry et al., 1996AJ....111..439H 1996AJ....111..439H
N = Noyes et al., 1984ApJ...279..763N 1984ApJ...279..763N
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Byte-by-byte Description of file: tablea4.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
8- 12 F5.1 km/s Uvel U space velocity
14- 18 F5.1 km/s Vvel V space velocity
20- 24 F5.1 km/s Wvel W space velocity
26 A1 --- l_logAge Limit flag on logAge
27- 30 F4.2 [yr] logAge Age
32 A1 --- r_logAge Parameter used for age determination (1)
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Note (1): Parameter as follows:
U,V,W = from the corresponding space velocity component
E = from the total velocity.
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Byte-by-byte Description of file: tablea5.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
8- 12 F5.2 [Sun] [Fe/H] Metallicity
15 A1 --- r_[Fe/H] Reference for [Fe/H] (1)
17 A1 --- l_logAge Limit flag on logAge
18- 22 F5.2 [yr] logAge ? Age
23 A1 --- n_logAge [?] ? when not determined
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Note (1): References as follows:
K = Kunzli et al., 1997, Cat. J/A+AS/122/51
E = Edvardsson et al., 1993, Cat. J/A+AS/102/603
F = Fatava et al., 1997A&A...323..809F 1997A&A...323..809F
A = Assumed solar, no age derived
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Byte-by-byte Description of file: tablea6.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
8- 12 F5.2 [yr] logMinAge ? Minimum age
13 A1 --- u_logMinAge [?)] ?: value not determined
): uncertain value
15- 19 F5.2 [yr] logMedAge ? Medium age
20 A1 --- u_logMedAge [?)] ?: value not determined
): uncertain value
22- 26 F5.2 [yr] logUppAge ? Upper age
27 A1 --- u_logUppAge [?] ?: value not determined
28- 30 A3 --- n_logMinAge Method used for Minimum age determination (1)
32- 34 A3 --- n_logMedAge Method used for Medium age determination (1)
36- 38 A3 --- n_logUppAge Method used for Upper age determination (1)
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Note (1): Methods used as follows:
I = Isochrones
M = Metallicity
R = Rotation
C = Calcium
K = Kinematics
R+C = Average of the two methods R&C
M+K = Average of the two methods M&K
I+A = Average of the two methods I&A
A = Results from arbitrarily fixed maximum or minimum age
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History:
Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 28-Mar-2000