J/MNRAS/383/183 CaII triplet of RGB from VLT/FLAMES obs. (Battaglia+, 2008)
Analysis and calibration of CaII triplet spectroscopy of red giant branch stars
from VLT/FLAMES observations.
Battaglia G., Irwin M., Tolstoy E., Hill V., Helmi A., Letarte B.,
Jablonka P.
<Mon. Not. R. Astron. Soc., 383, 183-199 (2008)>
=2008MNRAS.383..183B 2008MNRAS.383..183B
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Stars, giant ;
Spectroscopy
Keywords: techniques: spectroscopic - stars: abundances - galaxies: dwarf -
galaxies: star clusters
Abstract:
We demonstrate that low-resolution CaII triplet (CaT) spectroscopic
estimates of the overall metallicity ([Fe/H]) of individual red giant
branch (RGB) stars in two nearby dwarf spheroidal galaxies (dSphs)
agree to ±0.1-0.2dex with detailed high-resolution spectroscopic
determinations for the same stars over the range -2.5<[Fe/H]←0.5.
For this study, we used a sample of 129 stars observed in low- and
high-resolution modes with VLT/FLAMES in the Sculptor and Fornax
dSphs. We also present the data-reduction steps we used in our
low-resolution analysis and show that the typical accuracy of our
velocity and CaT [Fe/H] measurement is ∼2km/s and 0.1dex,
respectively. We conclude that CaT[Fe/H] relations calibrated on
globular clusters can be applied with confidence to RGB stars in
composite stellar populations over the range -2.5<[Fe/H]←0.5.
Description:
The data sets presented here were collected between 2003 August and
2005 November. They consist of 15 pointings in the Sculptor dSph and
11 in the Fornax dSph spread over the galaxies. Some fields were
observed with 1h exposure time, whilst other fields have repeated
exposures of shorter integration time and two different plate set-ups,
with the aim of testing the reliability of the derived velocities, EWs
and the stability of the instrument.
All the low-resolution CaT observations were made using VLT/FLAMES in
Medusa mode.
Objects:
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RA (2000) DE Designation(s)
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00 24 05.2 -72 04 51 NGC 104 = Cl Melotte 1
15 18 33.8 +02 04 58 NGC 5904 = M 5
10 17 36.8 -46 24 40 NGC 3201 = C 1015-461
12 39 28.0 -26 44 34 NGC 4590 = M 68
01 00 09.4 -33 41 32 Sculptor = ESO 351-30
02 39 59.3 -34 26 57 Fornax = ESO 356-4
---------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 98 69 Sample of the relevant data for the stars in the
globular clusters NGC 104, NGC 3201, NGC 4590 and
NGC 5904 observed with VLT/FLAMES at low resolution,
and that we used in the analysis of the CaT-[Fe/H]
calibration.
table4.dat 112 129 Sample of the relevant data for the stars observed
with VLT/FLAMES at both low- and high-resolution and
in the Sculptor and Fornax dSphs, and used in the
analysis of the CaT-[Fe/H] calibration.
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See also:
J/MNRAS/327/918 : CaII in extragalactic red giants (Tolstoy+, 2001)
J/A+A/459/423 : VI and [Fe/H] of Fornax dSph RGB stars (Battaglia+, 2006)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Cluster Globular cluster name
10- 13 A4 --- --- [GB07]
15- 24 A10 --- GB07 Star identification (1)
27- 28 I2 h RAh Right ascension (J2000) (2)
30- 31 I2 min RAm Right ascension (J2000) (2)
33- 37 F5.2 s RAs Right ascension (J2000) (2)
39 A1 --- DE- Declination sign (J2000) (2)
40- 41 I2 deg DEd Declination (J2000) (2)
43- 44 I2 arcmin DEm Declination (J2000) (2)
46- 49 F4.1 arcsec DEs Declination (J2000) (2)
51- 56 F6.3 mag Vmag V magnitude (2)
58- 62 F5.3 mag e_Vmag rms uncertainty on Vmag (2)
64- 70 F7.2 km/s HV Heliocentric velocity
72- 75 F4.2 km/s e_HV rms uncertainty on HV
77- 81 F5.3 0.1nm EW Summed Ca triplet equivalent width (EW2+EW3)
83- 87 F5.3 0.1nm e_EW rms uncertainty on EW
89- 93 F5.2 [Sun] [Fe/H]LR Low-resolution metallicity (G1)
95- 98 F4.2 [Sun] e_[Fe/H]LR rms uncertainty on [Fe/H]LR
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Note (1): Star names are GB07 TUCNNNN for NGC 104, GB07 N3201-SNNN for
NGC 3201, GB07 M68-SNNN for NGC 4590 and GB07 M5-SNNNN for NGC 5904.
Note (2): The photometry and astrometry are from Stetson
(2000PASP..112..925S 2000PASP..112..925S).
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 A8 --- Galaxy Galaxy name (Sculptor or Fornax)
10- 13 A4 --- --- [GB07]
15- 19 A5 --- GB07 Star identification (1)
21 I1 h RAh Right ascension (J2000) (2)
23- 24 I2 min RAm Right ascension (J2000) (2)
26- 30 F5.2 s RAs Right ascension (J2000) (2)
32 A1 --- DE- Declination sign (J2000) (2)
33- 34 I2 deg DEd Declination (J2000) (2)
36- 37 I2 arcmin DEm Declination (J2000) (2)
39- 42 F4.1 arcsec DEs Declination (J2000) (2)
44- 49 F6.3 mag Vmag V magnitude (2)
51- 55 F5.3 mag e_Vmag rms uncertainty on Vmag (2)
57- 62 F6.2 km/s HV Heliocentric velocity
64- 67 F4.2 km/s e_HV rms uncertainty on HV
69- 73 F5.3 0.1nm EW Summed Ca triplet equivalent width (EW2+EW3)
75- 79 F5.3 0.1nm e_EW rms uncertainty on EW
81- 85 F5.2 [Sun] [Fe/H]LR Metallicity derived from low-resolution
observations
87- 90 F4.2 [Sun] e_[Fe/H]LR rms uncertainty on [Fe/H]LR
92- 96 F5.2 [Sun] [Fe/H]HR Metallicity derived from high-resolution
observations (G1)
98-101 F4.2 [Sun] e_[Fe/H]HR rms uncertainty on [Fe/H]HR
103-107 F5.2 [Sun] [Ca/Fe] ?=9.99 Ca abundance derived from high
resolution observations (3)
109-112 F4.2 [Sun] e_[Ca/Fe] rms uncertainty on [Ca/Fe]HR
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Note (1): Star names as GB07 SclNN for Sculptor and GB07 FnxNN for Fornax.
Note (2): The photometry and astrometry are from our ESO/WFI observations
(Tolstoy et al., 2004, Cat. J/MNRAS/327/918 and Battaglia et al.,
2006, Cat. J/A+A/459/423).
Note (3): Those stars with [Ca/Fe]=9.99 had too low S/N to allow a
determination of the HR [Ca/H].
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Global notes:
Note (G1):
Derived from the low-resolution observations applying equation (16).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 22-Apr-2008