J/AJ/160/217 342 FGK-dwarfs ages using GALEX FUV magnitudes (Crandall+, 2020)
Estimating the ages of FGK dwarf stars through the use of GALEX FUV magnitudes.
Crandall S., Smith G.H., Subramonian A., Ho K., Cochrane E.M.
<Astron. J., 160, 217 (2020)>
=2020AJ....160..217C 2020AJ....160..217C
ADC_Keywords: Stars, dwarfs; Stars, F-type; Stars, G-type; Stars, K-type;
Photometry, ultraviolet; Optical; Stars, ages; Colors
Keywords: Stellar evolution ; Stellar activity ; Ultraviolet photometry ;
Milky Way evolution ; Milky Way disk
Abstract:
Stellar age cannot be directly measured, yet age determinations are
fundamental to understanding the evolution of stars, planets, and
galaxies. The work presented here builds upon the idea of a
stellar-activity age. We utilized far-ultraviolet (FUV) photometry
acquired by the Galaxy Evolution Explorer (GALEX) space telescope as
an indicator of chromospheric activity to infer ages of late-F, G, and
K type dwarf stars. We derived a purely empirical correlation between
FUV magnitudes and stellar age in conjunction with (B-V) color. Our
attention is restricted to Sun-like stars with color range
0.55≤(B-V)≤0.71 and absolute magnitude range 4.3≤MV≤5.3. The
correlation is defined in terms of a FUV-excess parameter
Q(FUV-B,B-V). We related stellar age, τ, to Q through the relation
loge(τ)=loge(a)+bQ, where a and b are fit parameters and
functions of (B-V). This correlation is functional up to 6Gyr for FGK
dwarfs. With such a correlation, one only needs Johnson (B-V) and FUV
measurements to estimate the stellar age for Population i dwarf stars
of solar-like temperature and metallicity. Such a calibration has
utility in population studies of FGK dwarfs for further understanding
of the chemical evolution of the Milky Way. As an illustration of one
such application, we have constructed activity and FUV-age
distributions for a sample of thin and thick disk stars, as
distinguished by their chemical abundances. Considerable overlap is
found between the activity distribution and age range of the two
populations. We discuss the possibility that some high-[α/Fe]
thick disk stars were formed as a result of the accretion of dwarf
galaxies as recently as 4Gyr ago.
Description:
We utilized far-ultraviolet (FUV) photometry acquired by the Galaxy
Evolution Explorer (GALEX) space telescope as an indicator of
chromospheric activity to infer ages of late-F, G, and K type dwarf
stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 37 342 Properties of field Star used in FUV-Age calibration
table5.dat 38 174 Thick and thin disk constituents
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See also:
B/simbad : Simbad objects catalogue (M.Wenger 2000)
V/117 : Geneva-Copenhagen Survey of Solar neighbourhood (Holmberg+, 2007)
J/PASP/106/281 : Photometry and radial velocities in NGC752 (Daniel+, 1994)
J/AJ/119/1760 : M54 and Sgr dSph VI photometry (Layden+, 2000)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/AJ/133/270 : Metallicities and ages in Leo II dSph (Koch+, 2007)
J/A+A/484/815 : Scaled solar tracks and isochrones (Bertelli+, 2008)
J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)
J/A+A/508/355 : Scaled solar tracks and isochrones (Bertelli+, 2009)
J/ApJ/725/875 : Chromospheric activity for CPS stars (Isaacson+, 2010)
J/A+A/530/A138 : Geneva-Copenhagen survey re-analysis (Casagrande+, 2011)
J/MNRAS/422/2024 : X-ray-age relation and exoplanet evaporation (Jackson+,2012)
J/ApJ/775/55 : Spitzer IR excesses in A-K stars (Ballering+, 2013)
J/ApJ/785/33 : High quality Spitzer/MIPS obs. F4-K2 stars (Sierchio+, 2014)
J/ApJS/225/32 : Extended abundance analysis of cool stars (Brewer+, 2016)
J/A+A/606/A94 : Chemical abundances of 1059 FGK stars (Delgado Mena+, 2017)
J/A+A/619/A73 : Solar Twins age-chromo. activity (Lorenzo-Oliveira+, 2018)
J/ApJ/862/33 : Improved & expanded member. catalog NGC752 (Agueros+, 2018)
J/ApJ/861/153 : Ultraviolet Extinction in the GALEX Bands. UVEXT (Sun+,2018)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 1 A1 --- r_Name Source catalog (1)
3- 11 A9 --- Name Name in HD catalog
13- 16 F4.2 mag Vmag [5.03/9.61] V band magnitude
18- 21 F4.2 mag B-V [0.55/0.7] Color, B-V
23- 27 F5.2 mag FUV-B [9.72/12.59] Color, FUV-B
29- 33 F5.2 --- Q [-2.83/-0.41] FUV-excess parameter determined by
Equation 2
35- 37 F3.1 Gyr Age [0.1/9] Literature quoted age (2)
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Note (1): Catalogs as follows:
i = Isaacson & Fischer, 2010, J/ApJ/725/875
b = Ballering+, 2013, J/ApJ/775/55
s = Sierchio+, 2014, J/ApJ/785/33
l = Lorenzo-Oliveira+, 2018, J/A+A/619/A73
Note (2): Literature-quoted ages with the majority derived from stellar
chromospheric and coronal activity indicators, and ages from other
sources (e.g. surface gravity, gyrochronology, isochrones) being less
commonly adopted.
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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- 9 A9 --- Name Name in HD catalog (1)
11- 14 F4.2 mag B-V [0.58/0.68] Color, B-V
16- 20 F5.2 mag FUVmag [17.39/21.81] FUV magnitude
22- 26 F5.2 [-] a/Fe [-0.16/0.78] Abundance, α elements to iron
28- 32 F5.2 --- Q [-2.26/0.19] FUV-excess parameter determined by
Equation 2
34- 38 A5 --- Disk Thin (154 occurrences) or Thick (20 occurrences)
disk
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Note (1): These stars were collected from Delgado Mena+, 2017, J/A+A/606/A94.
We reduced the sample to include stars with GALEX
FUV magnitudes and to those with colors 0.575≤(B-V)≤0.685.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 21-Jan-2021