J/ApJ/663/296 UBV(RI)c phot. of omega Cen (NGC5139) subgiants (Villanova+, 2007)
The multiplicity of the subgiant branch of ω Centauri:
evidence for prolonged star formation.
Villanova S., Piotto G., King I.R., Anderson J., Bedin L.R., Gratton R.G.,
Cassisi S., Momany Y., Bellini A., Cool A.M., Recio-Blanco A., Renzini A.
<Astrophys. J., 663, 296-314 (2007)>
=2007ApJ...663..296V 2007ApJ...663..296V
ADC_Keywords: Clusters, globular ; Stars, giant ; Photometry, HST ;
Photometry, UBVRI
Keywords: Galaxy: abundances - globular clusters: individual (NGC 5139) -
Hertzsprung-Russell diagram
Abstract:
We combine spectroscopic and photometric data for subgiant stars of
ω Cen to extract results that neither data set could have
provided on its own. GIRAFFE@VLT spectra of 80 stars at R=6400 give
metallicities for all of them and abundances of C, N, Ca, Ti, and Ba
for a subset of them. The photometric data, which have unusually high
accuracy, come from a ∼10x10arcmin2 mosaic of HST ACS images
centered on the cluster center and on multicolor images of a
∼34x33arcmin2 field, taken with the camera. Stars with
[Fe/H]←1.25 have a large magnitude spread on the flat part of the
sub-giant branch (SGB). We interpret this as empirical evidence for an
age spread, and from theoretical isochrones we derive a relative age
for each star.
Description:
Our photometric Hubble Space Telescope (HST) study is based on a
mosaic of 3x3 HST Advanced Camera for Surveys (ACS) Wide Field
Channel (WFC) fields taken in GO-9442 (PI Cool).
The ground-based component of our photometry is based on 187 images
taken from 1999 to 2003 with the camera (hereafter WFI).
Exposure times cover the range 5-1800s in Johnson U, B, and V, and
in Cousins RC and IC, plus some observations with the 665 and
658nm narrowband filters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 22 Stars observed at HST
table2.dat 72 57 Stars observed at WFI
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See also:
J/AJ/108/1350 : Omega Cen FUV photometry (Whitney+, 1994)
J/AJ/114/1087 : Omega Cen radial velocities (Mayor+ 1997)
J/AJ/119/1225 : Stroemgren photometry of Omega Cen & NGC 6397 (Hughes+ 2000)
J/AJ/119/1824 : Caby photometry of Ω Centauri (Rey+, 2000)
J/A+A/400/521 : Omega Cen XMM observations (Gendre+, 2003)
J/A+A/420/173 : JK photometry of Omega Cen red giants (Sollima+, 2004)
J/AJ/127/980 : vby and BVI photometry of Omega Cen giants (Hughes+, 2004)
J/MNRAS/357/265 : BVI photometry of omega Cen red giants (Sollima+, 2005)
J/ApJ/661/L155 : Radial velocities Rgb stars in omega Cen (Pancino+, 2007)
J/A+A/445/503 : Radial velocities in Omega Cen (NGC5139) (Reijns+, 2006)
J/ApJ/654/915 : Deep FORS1 BR photometry of omega Cen (Sollima+, 2007)
J/MNRAS/382/1353 : Spectral atlas of omega Cen post-MS stars (Van Loon+, 2007)
J/AJ/135/1395 : omega Cen Spitzer photometry (Boyer+, 2008)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- PKD Sequential number,
Cl* NGC 5139 PKD NNNNN in Simbad
7- 16 F10.6 deg RAdeg Right ascension in decimal degrees (J2000.0)
18- 27 F10.6 deg DEdeg Declination in decimal degrees (J2000.0)
29- 33 F5.2 mag F435W HST F435W magnitude
35- 38 F4.2 mag F435W-F625W HST F435W-F625W colour index
40- 44 F5.2 mag Vmag Johnson V magnitude
46- 48 I3 km/s HRV Heliocentric radial velocity
50- 53 I4 K Teff Effective temperature
55- 57 F3.1 [cm/s2] logg Surface gravity
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- PKD Sequential number,
Cl* NGC 5139 PKD NNNNN in Simbad
7- 16 F10.6 deg RAdeg Right ascension in decimal degrees (J2000.0)
18- 27 F10.6 deg DEdeg Declination in decimal degrees (J2000.0)
29- 33 F5.2 mag Vmag Johnson V magnitude
35- 38 F4.2 mag B-V Johnson B-V colour index
40- 43 F4.2 mag V-Ic Johnson-Cousins V-I colour index
45- 48 F4.2 mag V-Rc Johnson-Cousins V-R colour index
50- 52 I3 km/s HRV Heliocentric radial velocity
54- 57 I4 K Teff Effective temperature
59- 61 F3.1 [cm/s2] logg Surface gravity
63- 67 F5.2 [-] [Fe/H] Metallicity
69- 72 F4.2 Gyr Age Estimated age
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Aug-2009