J/A+A/524/A44 CN and CH line strengths in 12 globulars (Pancino+, 2010)
Low-resolution spectroscopy of main sequence stars belonging to 12 Galactic
globular clusters.
I. CH and CN band strength variations.
Pancino E., Rejkuba M., Zoccali M., Carrera R.
<Astron. Astrophys. 524, A44 (2010)>
=2010A&A...524A..44P 2010A&A...524A..44P
ADC_Keywords: Clusters, globular ; Spectroscopy ; Stars, dwarfs ;
Stars, early-type
Keywords: stars: abundances - stars: early-type
Abstract:
Globular clusters show star-to-star abundance variations for light
elements that are not yet well understood. The preferred explanation
involves a self-enrichment scenario, within which two subsequent
generations of stars co-exist in globular clusters. Observations of
chemical abundances in the main sequence and sub-giant branch stars
allow us to investigate the signature of this chemically processed
material without the complicating effects caused by stellar evolution
and internal mixing.
Our main goal is to investigate the carbon-nitrogen anti-correlation
with low-resolution spectroscopy of 20-50 stars fainter than the first
dredge-up in seven Galactic globular clusters (NGC288, NGC1851,
NGC5927, NGC6352, NGC6388, and Pal12) with different properties. We
complemented our observations with 47Tuc archival data, with four
additional clusters from the literature (M15, M22, M55, NGC362), and
with additional literature data on NGC288.
Description:
In this first paper, we measured the strength of the CN and CH band
indices, which correlate with the N and C abundances, and we
investigated the anti-correlation and bimodality of these indices. We
compared rCN, the ratio of stars belonging to the CN-strong and
weak groups, with 15 different cluster parameters.
Objects:
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RA (2000) DE Designation(s)
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00 24 05.4 -72 04 53 NGC 104 = GCl 1
05 14 06.3 -40 02 50 NGC 1851 = GCl 9
00 52 45.3 -26 34 43 NGC 288 = GCl 2
15 28 00.4 -50 40 22 NGC 5927 = = GCl 35
17 25 29.2 -48 25 22 NGC 6352 = GCl 64
17 36 17.5 -44 44 08 NGC 6388 = GCl 70
19 10 51.8 -59 58 55 NGC 6752 = GCl 108
21 46 38.8 -21 15 03 Pal 12 = GCl 123
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 80 346 CH and CN bands index measurements
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See also:
J/A+A/486/437 : CN and CH line strengths in 8 Galactic GlCl (Kayser+, 2008)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- GGC Cluster name
10- 13 I4 --- Seq Star sequential number in cluster
15- 23 F9.5 deg RAdeg Right ascension (J2000.0)
25- 33 F9.5 deg DEdeg Declination (J2000.0)
35- 40 F6.3 --- CN S3839(CN) band strength index
42- 47 F6.3 --- dCN S3839(CN) corrected for Teff and logg effects
49- 53 F5.3 --- e_CN Poisson uncertainty on S3839(CN)
55- 59 F5.3 --- CH CH4300 band strength index
61- 66 F6.3 --- dCH CH4300 corrected for Teff and logg effects
68- 72 F5.3 --- e_CH Poisson uncertainty on CH4300
74- 77 I4 km/s HRV Heliocentric radial velocity
79- 80 I2 km/s e_HRV Uncertainty on radial velocity
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Acknowledgements:
Elena Pancino, elena.pancino(at)oabo.inaf.it
(End) Elena Pancino [INAF-OABo, Italy], Patricia Vannier [CDS] 13-Sep-2010