J/ApJ/700/523 Galactic star clusters in SDSS. II. Colors. (An+, 2009)
Galactic globular and open clusters in the Sloan digital sky survey.
II. Test of theoretical stellar isochrones.
An D., Pinsonneault M.H., Masseron T., Delahaye F., Johnson J.A.,
Terndrup D.M., Beers T.C., Ivans I.I., Ivezic Z.
<Astrophys. J., 700, 523-544 (2009)>
=2009ApJ...700..523A 2009ApJ...700..523A
ADC_Keywords: Clusters, globular ; Associations, stellar ; Photometry, SDSS ;
Effective temperatures ; Models ; Abundances
Keywords: globular clusters: individual (M3, M5, M13, M15, M71, M92) -
Hertzsprung-Russell (HR) diagram - open clusters and associations:
individual (M67, NGC 6791) - stars: evolution - surveys
Abstract:
We perform an extensive test of theoretical stellar models for
main-sequence (MS) stars in ugriz, using cluster fiducial sequences
obtained in the previous paper of this series. We generate a set of
isochrones using the Yale Rotating Evolutionary Code with updated
input physics, and derive magnitudes and colors in ugriz from MARCS
model atmospheres. These models match cluster MSs over a wide range of
metallicity within the errors of the adopted cluster parameters.
However, we find a large discrepancy of model colors at the lower MS
(Teff≲4500K) for clusters at and above solar metallicity. We also
reach similar conclusions using the theoretical isochrones of Girardi
et al. and Dotter et al., but our new models are generally in better
agreement with the data. Using our theoretical isochrones, we also
derive MS-fitting distances and turnoff ages for five key globular
clusters, and demonstrate the ability to derive these quantities from
photometric data in the Sloan Digital Sky Survey. In particular, we
exploit multiple color indices (g-r, g-i, and g-z) in the parameter
estimation, which allows us to evaluate internal systematic errors.
Our distance estimates, with an error of σ(m-M)=0.03-0.11mag
for individual clusters, are consistent with Hipparcos-based
subdwarf-fitting distances derived in the Johnson-Cousins or Stromgren
photometric systems.
Description:
Cluster photometry was obtained in Paper I (An et al.,
2008ApJS..179..326A 2008ApJS..179..326A) from the SDSS ugriz imaging data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 51 2107 Bolometric corrections and synthetic colors in ugriz
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See also:
J/MNRAS/405/1711 : VRIg'i' photometry of 7 M15 giants (Mcdonald+, 2010)
J/A+A/486/941 : Abundances in M71 (NGC 6838) (Alves-Brito+, 2008)
J/AJ/133/1585 : Stromgren photometry in NGC 6791 (Anthony-Twarog+, 2007)
J/A+A/320/757 : M3 stars CCD photometry (Ferraro+ 1997)
J/AJ/107/1745 : HST UVI photometry of M15. II. (Yanny+, 1994)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 F4.1 [Sun] [Fe/H] Metallicity
6- 8 F3.1 [Sun] [a/Fe] log(α/Fe) abundance ratio
10- 13 I4 K Teff Effective temperature
15- 17 F3.1 [cm/s2] log(g) Log of surface gravity
19- 24 F6.3 mag BC Bolometric correction for r band
26- 30 F5.3 mag u-g The SDSS (u-g) color index (1)
32- 37 F6.3 mag g-r The SDSS (g-r) color index (1)
39- 44 F6.3 mag g-i The SDSS (g-i) color index (1)
46- 51 F6.3 mag g-z The SDSS (g-z) color index (1)
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Note (1): The AB corrections for the SDSS magnitudes and empirical color
corrections are not applied.
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History:
From electronic version of the journal
References:
An et al. Paper I. 2008ApJS..179..326A 2008ApJS..179..326A
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 19-Jul-2011