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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
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:
FileName Lrecl Records Explanations
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
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
Bytes Format Units Label Explanations
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)
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
Byte-by-byte Description of file: tablea2.dat
Bytes Format Units Label Explanations
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)
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 B = Baliunas, Sokoloff and Soon, 1996ApJ...457L..99B S = Saar & Osten, 1997MNRAS.284..803S
Byte-by-byte Description of file: tablea3.dat
Bytes Format Units Label Explanations
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
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 H = Henry et al., 1996AJ....111..439H N = Noyes et al., 1984ApJ...279..763N
Byte-by-byte Description of file: tablea4.dat
Bytes Format Units Label Explanations
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)
Note (1): Parameter as follows: U,V,W = from the corresponding space velocity component E = from the total velocity.
Byte-by-byte Description of file: tablea5.dat
Bytes Format Units Label Explanations
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
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 A = Assumed solar, no age derived
Byte-by-byte Description of file: tablea6.dat
Bytes Format Units Label Explanations
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)
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
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 28-Mar-2000
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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