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J/ApJ/706/1277       Stromgren photometry in ω Cen       (Calamida+, 2009)

Stromgren photometry of Galactic globular clusters. II. Metallicity distribution of red giants in ω Centauri. Calamida A., Bono G., Stetson P.B., Freyhammer L.M., Piersimoni A.M., Buonanno R., Caputo F., Cassisi S., Castellani M., Corsi C.E., Dall'Ora M., Degl'Innocenti S., Ferraro I., Grundahl F., Hilker M., Iannicola G., Monelli M., Nonino M., Patat N., Pietrinferni A., Prada Moroni P.G., Primas F., Pulone L., Richtler T., Romaniello M., Storm J., Walker A.R. <Astrophys. J., 706, 1277-1298 (2009)> =2009ApJ...706.1277C
ADC_Keywords: Clusters, globular ; Photometry, uvby ; Photometry, infrared Keywords: globular clusters: general - globular clusters: individual (Omega Centauri) - stars: abundances - stars: evolution Abstract: We present new intermediate-band Stromgren photometry based on more than 300 u, v, b, y images of the Galactic globular cluster ω Cen. Optical data were supplemented with new multiband near-infrared (NIR) photometry (350 J, H, Ks images). The final optical-NIR catalog covers a region of more than 20x20arcmin squared across the cluster center. We use different optical-NIR color-color planes together with proper-motion data available in the literature to identify candidate cluster red-giant (RG) stars. By adopting different Stromgren metallicity indices, we estimate the photometric metallicity for ∼4000 RGs, the largest sample ever collected. We identify four distinct subpopulations, namely, MP ([Fe/H]≤-1.49), metal-intermediate (MI; -1.49<[Fe/H]≤-0.93), metal-rich (MR; -0.95<[Fe/H]≤-0.15), and solar metallicity ([Fe/H]∼0). The last group includes only a small fraction of stars (∼8%±5%) and should be confirmed spectroscopically. Moreover, using the difference in metallicity based on different photometric indices, we find that the 19%±1% of RGs are candidate CN-strong stars. Description: A set of 110 uvby Stromgren images centered on the cluster ω Cen was collected by one of us L. Freyhammer (LF) over 11 nights between 1999 March 27 to April 9, with the 1.54m Danish Telescope (ESO, La Silla). This data set has been supplemented with 30 uv by images of the SW quadrant of ω Cen collected by one of us F. Grundahl (FG) during four nights in 1999 April and two nights in 1999 June with the Danish Telescope. Together with the aforementioned images, we also acquired 210 vby images collected with the same telescope by two of us (M. Hilker (MH), T. Richtler (TR)) in two observing runs (1993 and 1995; see Hilker 2000A&A...355..994H). See Figure 1. NIR J-, H-, and Ks-band images of ω Cen were collected in two different runs - 2001 February 5, 7, and 2002 February 2, 3, 24, 25 - with the NIR camera SOFI at the NTT (ESO, La Silla). Moreover, we also retrieved from the ESO archive two more data sets collected during the nights 2004 June 3, 4 and 2005 April 2. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 74 135 Log of scientific CCD images of ω Cen collected by L. Freyhammer (central field) and by F. Grundahl (SW fields) table4.dat 74 193 Log of scientific CCD images of ω Centauri collected by M. Hilker (see fields in Figure 1) table6.dat 74 355 Log of scientific NIR CCD images of ω Centauri table7.dat 27 114 Set of Stroemgren standard stars observed by F. Grundahl (FG) table8.dat 26 88 Log of standard stars of the reference photometric night
See also: J/ApJ/698/2048 : Abundances of red giants in ω Cen (Johnson+, 2009) J/MNRAS/396/2183 : Radial velocities of red giants in ω Cen (Sollima+ 2009) J/MNRAS/357/265 : BVI photometry of omega Cen red giants (Sollima+, 2005) J/A+A/420/173 : JK photometry of Omega Cen red giants (Sollima+, 2004) J/AJ/127/1227 : Synthetic Stroemgren photometry (Clem+, 2004) J/AJ/119/1225 : Stroemgren photometry of Omega Cen and NGC 6397 (Hughes+, 2000) J/A+AS/104/429 : uvby Photometry of G-type dwarfs (Olsen 1994) J/A+AS/102/89 : uvby-beta Photometry of G5 stars (Olsen 1993) Byte-by-byte Description of file: table3.dat table4.dat table6.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Run Observation run identification 14- 27 A14 --- Frame Frame identification 29- 32 A4 --- Field Field identification 34- 43 A10 "YYYY/MM/DD" Date UT Day of the observation 45- 56 F12.4 d HJD Heliocentric Julian Date 58- 61 I4 s Exp Individual exposure time (G2) 63- 69 A7 --- Filt Stromgren or near-IR filter used (G1) 71- 74 F4.2 arcsec See Individual seeing
Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Star name (1) 10- 19 A10 "YYYY/MM/DD" Date UT Day of the observation (2) 21- 27 A7 --- Filt [u,v,b,y] Filter used (u,v,b,y together)
Note (1): Standard stars have been selected from catalogs of photometric standards of Olsen (1993, Cat. J/A+AS/102/89) and Schuster & Nissen (1988A&AS...73..225S). See text for more details. Note (2): Data set collected between April 1999 and June 1999 with the 1.54m Danish Telescope available at ESO (La Silla).
Byte-by-byte Description of file: table8.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Name Star name (1) 10- 21 F12.4 d HJD Heliocentric Julian Date 23- 24 I2 s Exp Individual exposure time 26 A1 --- Filt [buvy] Filter used (Stromgren b,u,v or y)
Note (1): HD standard stars have been observed during the night of June the 6th, 1999, with the 1.54m Danish Telescope available at ESO (La Silla).
Global Notes: Note (G1): filters are: * either the u, v, b, y Stromgren filters of the 1.54m Danish Telescope (ESO, La Silla) in tables 3 and 4 * or the J, H, Ks NIR filters of the NTT Telescope (ESO, La Silla). "NB_" data were collected using two narrowband filters centered on λ=1.21um and λ=2.19um from the NIR camera ISAAC at the VLT (ESO, Paranal) in table 6. Note (G2): Exp is the total exposure time: ET=DIT*NDIT (with DIT: detector integration time and NDIT: number of DIT).
History: From electronic version of the journal References: Calamida et al. Paper I. 2007ApJ...670..400C
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 15-Dec-2011
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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