J/MNRAS/427/2647 Sgr dSph stars spectral classification (McDonald+, 2012)
Carbon enrichment of the evolved stars in the Sagittarius dwarf spheroidal.
McDonald I., White J.R., Zijlstra A.A., Guzman Ramirez L., Szyszka C.,
van Loon J.T., Lagadec E., Jones O.C.
<Mon. Not. R. Astron. Soc., 427, 2647-2659 (2012)>
=2012MNRAS.427.2647M 2012MNRAS.427.2647M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, late-type ; Stars, carbon ;
Stars, luminous ; Radial velocities; Spectroscopy ;
MK spectral classification ; Photometry, infrared
Keywords: stars: AGB and post-AGB - stars: abundances - stars: carbon -
circumstellar matter - stars: mass-loss -
galaxies: individual: Sgr dSph
Abstract:
We present spectra of 1142 colour-selected stars in the direction of
the Sagittarius Dwarf Spheroidal (Sgr dSph) galaxy, of which 1058 were
taken with VLT/FLAMES multi-object spectrograph and 84 were taken with
the SAAO Radcliffe 1.9-m telescope grating spectrograph. Spectroscopic
membership is confirmed (at >99 per cent confidence) for 592 stars on
the basis of their radial velocity, and spectral types are given. Very
slow rotation is marginally detected around the galaxy's major axis.
We identify five S stars and 23 carbon stars, of which all but four
carbon stars are newly determined and all but one (PQ Sgr) are likely
Sgr dSph members. We examine the onset of carbon richness in this
metal-poor galaxy in the context of stellar models. We compare the
stellar death rate (one star per 1000-1700yr) with the known
planetary nebula dynamical ages and find that the bulk population
produce the observed (carbon-rich) planetary nebulae. We compute
average lifetimes of S and carbon stars as 60-250 and 130-500kyr,
compared to a total thermal-pulsing asymptotic giant branch lifetime
of 530-1330kyr. We conclude by discussing the return of carbon-rich
material to the interstellar medium.
Description:
The bulk of our observed spectra were obtained using the ESO
VLT/FLAMES+MEDUSA multi-fibre spectrograph in GIRAFFE+UVES mode. These
cover nine fields of the Sgr dSph core, each taken in four settings
(L714.2, L682.2, H651.5B and H710.5). Simultaneous spectra were taken
using the UVES instrument using the red arm, cross-disperser CD3 and a
central wavelength of 580nm.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 74 1058 Spectral types and radial velocities of
targets observed with the VLT
table3.dat 41 84 Spectral types of targets observed with the
SAAO Radcliffe 1.9-m
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See also:
J/A+A/414/503 : Abundances in the Sgr dSph (Bonifacio+, 2004)
J/A+A/465/815 : Abundances of Sgr dSph stars (Sbordone+, 2007)
J/A+A/513/A62 : Sgr dSph VIMOS photometry & radial velocity (Giuffrida+, 2010)
J/A+A/520/A95 : Abundances of red giants in M54 and Sgr dSph (Carretta+, 2010)
J/ApJ/708/1290 : A 2MASS view of the Sgr dSph. VI. (Chou+, 2010)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq Sequential number (1)
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30- 31 A2 --- SpType Spectral type (G1)
33- 37 F5.2 mag Ksmag 2MASS Ks magnitude
39- 42 F4.2 mag J-Ks 2MASS J-Ks colour index
44- 50 F7.2 km/s HRV Heliocentric radial velocity
52- 57 F6.2 km/s sigma Velocity dispersion
59- 64 F6.2 % Pmemb Probability of membership of the Sgr dSph
66- 69 F4.2 --- TiO TiO band strength index
71- 74 F4.2 --- ZrO ZrO band strength index
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Note (1): Stars with IDs ≥1016 were observed with UVES, the remainder
with GIRAFFE.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq Sequential number
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 16 F5.2 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 28 F4.1 arcsec DEs Declination (J2000)
30 A1 --- SpType [CMU] Spectral type (G1)
32- 36 F5.2 mag Ksmag 2MASS Ks magnitude
38- 41 F4.2 mag J-Ks 2MASS J-Ks colour index
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Note (G1): Spectral types as follows:
U = unclassifiable
C = carbon-rich
M = oxygen-rich
K = no molecular features
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Acknowledgements:
Iain McDonald, mcdonald(at)jb.man.ac.uk
(End) Patricia Vannier [CDS] 09-Aug-2013