J/AJ/136/1039 CaII index of SMC red giant branch stars (Carrera+, 2008)
The chemical enrichment history of the Small Magellanic Cloud and its gradients.
Carrera R., Gallart C., Aparicio A., Costa E., Mendez R.A., Noel N.E.D.
<Astron. J., 136, 1039-1048 (2008)>
=2008AJ....136.1039C 2008AJ....136.1039C
ADC_Keywords: Magellanic Clouds ; Stars, giant ; Spectra, infrared ;
Radial velocities ; Photometry, VRI
Keywords: galaxies: evolution - galaxies: individual (SMC) -
galaxies: stellar content - Local Group - Magellanic Clouds
Abstract:
We present stellar metallicities derived from Ca II triplet
spectroscopy in over 350 red giant branch stars in 13 fields
distributed in different positions in the Small Magellanic Cloud,
ranging from ∼1° to ∼4° from its center. In the innermost fields,
the average metallicity is [Fe/H]~-1. This value decreases when we
move away toward outermost regions. This is the first detection of a
spectroscopic metallicity gradient in this galaxy. We show that the
metallicity gradient is related to an age gradient, in the sense that
more metal-rich stars, which are also younger, are concentrated in the
central regions of the galaxy.
Description:
The spectroscopic observations were carried on in service mode with
the VLT Antu telescope, at Paranal Observatory (Chile), through
program 074.B-0446.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 67 372 Red giants stars observed
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See also:
J/AJ/131/2514 : Radial velocities of red giants in the SMC (Harris+, 2006)
J/AJ/135/836 : Calcium triplet index in LMC stars (Carrera+, 2008)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of Right Ascension (J2000)
4- 5 I2 min RAm Minute of Right Ascension (J2000)
7- 10 F4.1 s RAs Second of Right Ascension (J2000)
12 A1 --- DE- Sign of the Declination (J2000)
13- 14 I2 deg DEd Degree of Declination (J2000)
16- 17 I2 arcmin DEm Arcminute of Declination (J2000)
19- 22 F4.1 arcsec DEs Arcsecond of Declination (J2000)
24- 28 F5.2 0.1nm W.CaT The CaT index (1)
30- 33 F4.2 0.1nm e_W.CaT The 1σ uncertainty in W.CaT
35- 39 F5.2 mag Vmag ?=99.99 The V band magnitude
41- 45 F5.2 mag Imag ?=99.99 The I band magnitude
47- 52 F6.1 km/s RV Radial velocity
54- 57 F4.1 km/s e_RV The 1σ uncertainty in RV
59- 67 A9 --- Comm Additional comment ("AGB", "AGB?" or
"No member")
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Note (1): Defined as ΣCa, the sum of the equivalent widths of the
three CaT lines (848.4-868.2nm). The metallicity
is given by: [Fe/H] =-2.95+0.3ΣCa+0.23MI,
where MI is the absolute I magnitude, and [Fe/H] is in the Carretta
& Gratton scale (1997, Cat. J/A+AS/121/95) metallicity scale.
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Nomenclature Note:
Sources identified as <[CGA2008] JHHMMSS.s+DDMMSS.s> in Simbad
History:
From electronic version of the journal
References:
Noel et al., Paper I 2007AJ....133.2037N 2007AJ....133.2037N
Carrera et al., Paper II 2007AJ....134.1298C 2007AJ....134.1298C, Cat. J/AJ/134/1298
Carrera et al., Paper III 2008AJ....135..836C 2008AJ....135..836C, Cat. J/AJ/135/836
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 06-Apr-2011