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J/AJ/127/840       VRI photometry of Fornax red giants            (Pont+, 2004)

The chemical enrichment history of the Fornax dwarf spheroidal galaxy from the infrared calcium triplet. Pont F., Zinn R., Gallart C., Hardy E., Winnick R. <Astron. J., 127, 840-860 (2004)> =2004AJ....127..840P
ADC_Keywords: Stars, giant ; Photometry ; Abundances, [Fe/H] ; Equivalent widths Keywords: galaxies: abundances - galaxies: individual (Fornax) - Local Group - stars: abundances Abstract: Near-infrared spectra were obtained for 117 red giants in the Fornax dwarf spheroidal galaxy with the FORS1 spectrograph on the VLT, in order to study the metallicity distribution of the stars and to lift the age-metallicity degeneracy of the red giant branch (RGB) in the color-magnitude diagram (CMD). Metallicities are derived from the equivalent widths of the infrared calcium triplet lines at 8498, 8542, and 8662Å calibrated with data from globular clusters, the open cluster M67, and the LMC. For a substantial portion of the sample, the strength of the calcium triplet is unexpectedly high, clearly indicating that the main stellar population of Fornax is significantly more metal-rich than could be inferred from the position of its RGB in the CMD. Description: The observations were obtained on the night of 1999 December 1, using the FORS1 instrument installed on the Cassegrain focus of the UT1 telescope (first 8.2m unit of the ESO Very Large Telescope) at Paranal, Chile. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 100 118 Fornax star data
See also: <I/185/> : Giant branch of Fornax dwarf spheroidal galaxy (Sagar+, 1990) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [PZG2004] Object identification number 5 I1 h RAh Hour of Right Ascension (J2000) 7- 8 I2 min RAm Minute of Right Ascension (J2000) 10- 14 F5.2 s RAs Second of Right Ascension (J2000) 16 A1 --- DE- Sign of the Declination (J2000) 17- 18 I2 deg DEd Degree of Declination (J2000) 20- 21 I2 arcmin DEm Arcminute of Declination (J2000) 23- 27 F5.2 arcsec DEs Arcsecond of Declination (J2000) 29- 34 F6.3 mag Vmag ? The V band magnitude (1) 36- 40 F5.3 mag e_Vmag ? The 1σ error in Vmag (1) 42- 47 F6.3 mag Rcmag ? The Cousins R band magnitude (1) 49- 53 F5.3 mag e_Rcmag ? The 1σ error in Rcmag (1) 55- 60 F6.3 mag Icmag The Cousins I band magnitude (1) 61 A1 --- u_Icmag Uncertainty flag on Imag 63- 67 F5.3 mag e_Icmag ? The 1σ error in Icmag (1) 69- 73 F5.3 mag V-Ic ? The (V-Ic) color (1) 75- 78 F4.2 0.1nm CaEW ? Weighted sum of the Ca widths (2) 80- 83 F4.2 0.1nm e_CaEW ? The 1σ error in CaEW 85- 89 F5.2 [Sun] [Fe/H] ? Metallicity 90 A1 --- u_[Fe/H] Uncertainty flag on [Fe/H] 92- 95 F4.2 [Sun] e_[Fe/H] ? The 1σ error in [Fe/H] 97- 99 A3 --- n_[PZG2004] Additional notes on [PZG2004] (3)
Note (1): Photometry from Gallart et al. (in prep.). Note (2): Where CaEW = 0.5w1 + w2 + 0.6w3, where w1, w2 and w3 are the equivalent widths of individual Calcium lines (λ 8498, 8542, 8662 Angstroms, respectively). Note (3): Notes are numbered as follows: 1 = suspected non-member from radial velocity 2 = visible double 3 = no second spectrum 4 = second spectrum truncated 5 = large dip in the spectrum at 8680Å 6 = faint visible companion 7 = sky noise >7% g = equivalent width from Gaussian fit
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 02-Jul-2004
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