J/A+A/486/437 CN and CH line strengths in 8 Galactic GlCl (Kayser+, 2008)
Comparing CN and CH line strengths in a homogeneous spectroscopic sample
of 8 Galactic globular clusters.
Kayser A., Hilker M., Grebel E.K., Willemsen P.G.
<Astron. Astrophys., 486, 437-452 (2008)>
=2008A&A...486..437K 2008A&A...486..437K
ADC_Keywords: Clusters, globular ; Abundances
Keywords: stars: abundances - Galaxy: globular clusters: general
Abstract:
Our work focuses on the understanding of the origin of CNO-anomalies,
which have been detected in several Galactic globular clusters. The
novelty and advantage of this study is that it is based on a
homogeneous data set of hundreds of medium-resolution spectra of stars
in eight Galactic globular clusters (M 15, M 22, M 55, NGC 288,
NGC 362, NGC 5286, Palomar 12, and Terzan 7). Two of the clusters
(Palomar 12 and Terzan 7) are believed to be former members of the
Sagittarius dwarf spheroidal (Sgr dSph) galaxy. The large homogeneous
data set allows for a detailed differential study of the line
strengths in the stellar spectra of the observed clusters. Our sample
comprises stars in different evolutionary states, namely the
main-sequence turn-off (MSTO) region, the subgiant branch (SGB) and
the base of the red giant branch (RGB). We compare the relative CN and
CH line strengths of stars in the same evolutionary states (with
similar logg and Teff).
Description:
The spectroscopic data were obtained in May 2002 and July 2004 at the
VLT/UT4 at ESO/Paranal (Chile) with the multi-slit spectroscopy
instrument FORS2/MXU. FORS2 provides a field of view of 6.8'x6.8'.
The observations of M 55 were obtained in 2002.
The observations obtained in 2004 were dedicated to CN and CH
measurements in seven further Galactic globular clusters (M 15, M 22,
M 55, NGC 288, NGC 362, NGC 5286, Palomar 12, and Terzan 7) spanning a
large range in metallicity (-2.26<[Fe/H]←0.58dex).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 110 412 List of spectroscopic sample stars, ordered
by increasing V magnitude
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See also:
VII/103 : Galactic Globular Clusters (Monella 1985)
VII/151 : Galactic Globular Clusters Structure Parameters (Webbink 1985)
J/AJ/106/154 : HST Observations in inner region of M15 (Ferraro+ 1993)
J/PASP/109/883 : Globular metallicity scale. I. (Rutledge+ 1997)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Name of star observed (Cluster-NN) (1)
14- 22 F9.5 deg RAdeg Right ascension in decimal degrees (J2000)
24- 32 F9.5 deg DEdeg Declination in decimal degrees (J2000)
34- 38 F5.2 mag Vmag Apparent V magnitude as determined by PSF
photometry with DAOPHOT II under IRAF
40- 44 F5.2 mag B-V B-V color from PSF photometry
46- 51 F6.3 mag CN Measured CN strength index S3839
53- 57 F5.3 mag e_CN rms uncertainty on CN
59- 63 F5.3 mag CH Measured CH band strength index CH4300
65- 69 F5.3 mag e_CH rms uncertainty on CH
71- 76 F6.3 mag dCN Calculated CN-excess parameter δCN
78- 83 F6.1 km/s RV Radial velocity (2)
85- 87 A3 --- Type Star position on HR diagram (3)
89-110 A22 --- SName Simbad name of the star
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Note (1): Nomenclature note:
M 22-NNN = Cl* NGC 6656 KHG NN in Simbad
M 15-NNN = Cl* NGC 7078 KHG NN in Simbad
NGC 288-NNN = Cl* NGC 288 KHG NN in Simbad
NGC 362-NNN = Cl* NGC 362 KHG NN in Simbad
NGC 5286-NNN = Cl* NGC 5286 KHG NN in Simbad
Pal12-NNN = Cl* Palomar 12 KHG NN in Simbad
Ter7-NNN = Cl* Terzan 7 KHG NN in Simbad
Note (2): as determined from cross-correlation with FXCOR under IRAF and
not corrected for systematic errors. Thus, these velocities are only
indicative.
Note (3): Type describes to which part of the CMD the star most probably
belongs:
RGB = red giant branch
HB = horizontal branch
SGB = sub giant branch
MS = main sequence
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 30-Sep-2008