J/ApJ/682/1217 Abundances in red giants in 7 globular clusters (Kirby+, 2008)
Metallicity and alpha-element abundance measurement in red giant stars from
medium-resolution spectra.
Kirby E.N., Guhathakurta P., Sneden C.
<Astrophys. J., 682, 1217-1233 (2008)>
=2008ApJ...682.1217K 2008ApJ...682.1217K
ADC_Keywords: Clusters, globular ; Abundances, [Fe/H] ; Photometry, UBVRI ;
Stars, giant ; Spectroscopy
Keywords: globular clusters: individual (M13, M15, M71, M79, NGC 2419, NGC 7006,
NGC 7492) - stars: abundances
Abstract:
We present a technique that applies spectral synthesis to
medium-resolution spectroscopy (MRS; R∼6000) in the red
(6300Å<λ<9100Å) to measure [Fe/H] and [α/Fe] of
individual red giant stars over a wide metallicity range. We apply our
technique to 264 red giant stars in seven Galactic globular clusters
and demonstrate that it reproduces the metallicities and
α-enhancements derived from high-resolution spectroscopy (HRS).
The MRS technique excludes the three CaII triplet lines and instead
relies on a plethora of weaker lines. Unlike empirical metallicity
estimators, such as the equivalent width of the CaII triplet, the
synthetic method presented here is applicable over an arbitrarily wide
metallicity range and is independent of assumptions about the
α-enhancement.
Description:
We present observations of seven globular clusters with the Deep
Imaging Multi-Object Spectrometer (DEIMOS) on the Keck II telescope,
in 2006 Feb 2, 2007 Oct 12 and 2007 Nov 13,14,15.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 31 48236 Line list
table6.dat 155 264 Abundances for individual stars
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See also:
II/248 : UBV photometry and proper motions in M13 (Kadla, 1966)
J/A+A/505/117 : Abundances of red giants in 15 globular clusters (Carretta+,
2009)
J/A+A/505/139 : Abundances of red giants in 17 globular clusters (Carretta+,
2009)
J/A+A/486/941 : Abundances in M71 (NGC 6838) (Alves-Brito+, 2008)
J/AJ/129/1607 : Equivalent widths of 4 RGB in NGC 7492 (Cohen+, 2005)
J/PASP/117/37 : BVRI photometry in NGC 2419, Pal 4, and Pal 14 (Saha+, 2005)
J/A+AS/144/227 : BV photometry of M71 (Geffert+, 2000)
J/AJ/112/601 : UV photometry in M79 (Hill+ 1996)
J/AJ/107/230 : BVRI CCD photometry of NGC 1904 (Alcaino+, 1994)
J/A+AS/26/353 : UBV observations in globular NGC 1904 (Alcaino+, 1976)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 8 F8.3 0.1nm lambda Wavelength in Angstroms
10- 16 F7.3 --- Ion Species identification (1)
18- 23 F6.3 eV ExPot Excitation potential (2)
25- 31 F7.3 [-] log(gf) Log of oscillator strength (3)
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Note (1): A code representing the atomic or molecular species. The integer
part of the code is the element's atomic number. Codes greater than
100 represent molecules. For example, 607 represents CN. The first
decimal place of the code is the ionization state, where 0 is neutral.
Remaining decimal places are mass numbers for isotopic hyperfine
transitions.
Note (2): Any Fe I line with fewer than three decimal places of excitation
potential is invented to account for a line in the Sun and/or
Arcturus.
Note (3): The transitions that we modified have oscillator strengths with
fewer than three decimal places.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Cluster Cluster name
10- 11 I2 h RAh Hour of Right Ascension (J2000)
13- 14 I2 min RAm Minute of Right Ascension (J2000)
16- 19 F4.1 s RAs Second of Right Ascension (J2000)
21 A1 --- DE- Sign of the Declination (J2000)
22- 23 I2 deg DEd Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 29 I2 arcsec DEs Arcsecond of Declination (J2000)
31- 35 F5.2 mag Bmag ? B band magnitude (1)
37- 40 F4.2 mag e_Bmag ? Uncertainty in Bmag (1)
42- 46 F5.2 mag Vmag V band magnitude (1)
48- 51 F4.2 mag e_Vmag Uncertainty in Vmag (1)
53- 57 F5.2 mag Imag ? I band magnitude (1)
59- 62 F4.2 mag e_Imag ? Uncertainty in Imag (1)
64- 67 I4 K Teff Effective temperature
69- 72 F4.2 [cm/s2] log(g) Log of surface gravity
74- 78 F5.2 [Sun] [Fe/H]M Metallicity from Medium resolution spectroscopy
80- 83 F4.2 [Sun] e_[Fe/H]M Uncertainty in [Fe/H]M
85- 89 F5.2 [Sun] [a/Fe]M α enhancement from Medium resolution
spectroscopy
91- 94 F4.2 [Sun] e_[a/Fe]M Uncertainty in [a/Fe]M
96-100 F5.2 [Sun] [Fe/H]H ? Metallicity from High resolution spectroscopy
102-105 F4.2 [Sun] e_[Fe/H]H ? Uncertainty in [Fe/H]H
107-111 F5.2 [Sun] [a/Fe]H ? α enhancement from High resolution
spectroscopy (2)
113-116 F4.2 [Sun] e_[a/Fe]H ? Uncertainty in [a/Fe]H
118-135 A18 --- HRSaut High resolution spectroscopy author's reference
137-155 A19 --- BibCode High resolution spectroscopy bibcode
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Note (1): P. B. Stetson has generously provided this photometry, which is
preliminary pending his own publication of these data.
Note (2): See Section 5.3 for a discussion on [α/Fe]HRS
measurements of Sneden et al., 1997AJ....114.1964S 1997AJ....114.1964S, Sneden et al.,
2000AJ....120.1351S 2000AJ....120.1351S and Sneden et al., 2004AJ....127.2162S 2004AJ....127.2162S.
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Nomenclature note:
Individual stars are <[KGS2008] JHHMMSS.s+DDMMSS> in Simbad.
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 24-Nov-2010