2010A&A...513A..34S


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.15CEST08:25:58

2010A&A...513A..34S - Astronomy and Astrophysics, volume 513, A34-34 (2010/4-1)

The NIR CaII triplet at low metallicity. Searching for extremely low-metallicity stars in classical dwarf galaxies.

STARKENBURG E., HILL V., TOLSTOY E., GONZALEZ HERNANDEZ J.I., IRWIN M., HELMI A., BATTAGLIA G., JABLONKA P., TAFELMEYER M., SHETRONE M., VENN K. and DE BOER T.

Abstract (from CDS):

The NIR CaII triplet absorption lines have proven to be an important tool for quantitative spectroscopy of individual red giant branch stars in the Local Group, providing a better understanding of metallicities of stars in the Milky Way and dwarf galaxies and thereby an opportunity to constrain their chemical evolution processes. An interesting puzzle in this field is the significant lack of extremely metal-poor stars, below [Fe/H]=-3, found in classical dwarf galaxies around the Milky Way using this technique. The question arises whether these stars are really absent, or if the empirical CaII triplet method used to study these systems is biased in the low-metallicity regime. Here we present results of synthetic spectral analysis of the CaII triplet, that is focused on a better understanding of spectroscopic measurements of low-metallicity giant stars. Our results start to deviate strongly from the widely-used and linear empirical calibrations at [Fe/H]←2. We provide a new calibration for CaII triplet studies which is valid for -0.5≥[Fe/H]≥-4. We subsequently apply this new calibration to current data sets and suggest that the classical dwarf galaxies are not so devoid of extremely low-metallicity stars as was previously thought.

Abstract Copyright:

Journal keyword(s): stars: abundances - galaxies: dwarf - galaxies: evolution - Local Group - Galaxy: formation

Simbad objects: 11

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Number of rows : 11

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 HD 4306 SB* 00 45 27.1608069956 -09 32 39.781797287 9.80 9.75 9.02 8.75   G3/5w(A) 142 0
2 CD-38 245 Pe* 00 46 36.1954714218 -37 39 33.555736375   12.733 11.929 13.39 10.996 KIIvw 201 0
3 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1473 1
4 NAME Dwarf Elliptical Galaxy in Sex G 10 13 02.9 -01 36 53   12 10.4     ~ 706 0
5 HD 88609 Pe* 10 14 28.9854651931 +53 33 39.345145786 9.930 9.540 8.620 7.78 7.15 G5IIIw 186 0
6 HD 110184 Pe* 12 40 14.0784174924 +08 31 38.056629204 10.20 9.45 8.27 8.52   KIIvw 126 0
7 [NGW2008] 1137 RB? 13 58 33.8136936046 +14 21 08.487747327           ~ 18 0
8 HD 122563 Pe* 14 02 31.8456299772 +09 41 09.942736952 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 746 0
9 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2133 0
10 HD 216143 Pe* 22 50 31.0884300128 -06 54 49.557528724   8.78 7.81 7.44   G2/3(IV)(we) 128 0
11 NAME Local Group GrG ~ ~           ~ 6973 0

    Equat.    Gal    SGal    Ecl

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2020.07.15-08:25:58

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