J/MNRAS/336/879 G and K dwarfs UBV(RI)c and ubvy photometry (Kotoneva+, 2002)
K dwarfs and the chemical evolution of the solar cylinder.
Kotoneva E., Flynn C., Chiappini C., Matteucci F.
<Mon. Not. R. Astron. Soc. 336, 879 (2002)>
=2002MNRAS.336..879K 2002MNRAS.336..879K
ADC_Keywords: Stars, K-type ; Stars, G-type ; Stars, dwarfs ;
Photometry, UBVRI ; Photometry, Cousins ; Photometry, uvby
Keywords: stars: abundances - Galaxy: evolution
Abstract:
K dwarfs have lifetimes older than the present age of the Galactic
disc, and are thus ideal stars for investigating the chemical
evolution of the disc. We have developed several photometric
metallicity indicators for K dwarfs, based on a sample of accurate
spectroscopic metallicities for 34 disc and halo G and K dwarfs. The
photometric metallicities lead us to develop a metallicity index for K
dwarfs based only on their position in the colour-absolute-magnitude
diagram. Metallicities have been determined for 431 single K dwarfs
drawn from the Hipparcos catalogue, selecting the stars by absolute
magnitude and removing multiple systems. The sample is essentially a
complete reckoning of the metal content in nearby K dwarfs. We use
stellar isochrones to mark the stars by mass, and select a subset of
220 of the stars, which is complete within a narrow mass interval. We
fit the data with a model of the chemical evolution of the solar
cylinder. We find that only a modest cosmic scatter is required to fit
our age-metallicity relation. The model assumes two main infall
episodes for the formation of the halo-thick disc and thin disc,
respectively. The new data confirm that the solar neighbourhood formed
on a long time-scale of the order of 7Gyr.
Description:
Observations were made at Siding Spring Observatory (SSO), Australia,
between 1999 March 8 and 22. We measured Johnson-Cousins and
Stroemgren colours for all available Southern hemisphere stars of the
basic sample using the SSO 24-in telescope. We used the motorized
filter box with all eight filters U,B,V,R,I and Stroemgren v,b,y.
Further data were obtained at La Palma using the Swedish 60-cm
telescope in 2000 March. An SBIG charge-coupled device was used to
observe in the filters V, R and I.
We also obtained R-I colours for 108 stars from Bessell
(1990A&AS...83..357B 1990A&AS...83..357B), who observed all the stars in the Gliese
catalogue.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 118 431 Data set
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See also:
J/A+AS/129/237 : G and K dwarfs abundances (Feltzing+ 1998)
J/AJ/105/1962 : K and M dwarfs photometry (Weis, 1993)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HIP HIP (Cat. I/239) number
8- 13 I6 --- HD ?=-99999 HD (Cat. III/135) number
15- 19 F5.2 mag Vmag Visual magnitude
21- 24 F4.2 mag VMAG Absolute V magnitude, as computed from
the Hipparcos parallax
26- 29 F4.2 mag B-V B-V colour index
31- 38 F8.2 mag Rc-Ic ?=99999.00 Cousins R-I colour index
40- 47 F8.2 mag m1 ?=99999.00 Stroemgren m1 colour index
49- 56 F8.2 mag c1 ?=99999.00 Stroemgren c1 colour index
58- 65 F8.2 mag b1 ?=99999.00 Geneva b1 colour index
67- 74 F8.2 [Sun] [Fe/H]m1 ?=99999.00 Stroemgren-based metallicity
76- 83 F8.2 [Sun] [Fe/H]b1 ?=99999.00 Geneva-based metallicity
85- 90 F6.3 [Sun] [Fe/H]KF Luminosity-based metallicity
92- 99 F8.2 km/s Uvel ?=99999.00 U space velocity
101-108 F8.2 km/s Vvel ?=99999.00 V space velocity
110-117 F8.2 km/s Wvel ?=99999.00 W space velocity
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Acknowledgements: Eira Kotoneva
(End) Patricia Bauer [CDS] 24-Apr-2003