J/ApJS/111/377 Hγ & Hδ absorption features (Worthey+ 1997)
Hγ and Hδ absorption features in stars and stellar populations
Worthey G., Ottaviani D.L.
<Astrophys. J. Suppl. Ser. 111, 377 (1997)>
=1997ApJS..111..377W 1997ApJS..111..377W
ADC_Keywords: Populations, stellar ; Equivalent widths ; Balmer lines
Keywords: galaxies: evolution - galaxies: stellar content - line: profiles -
stars: abundances
Abstract:
The Hγ and Hδ absorption features are measured in a sample
of 455 (out of an original 460) Lick IDS stars with pseudo-equivalent
width indices. For each Balmer feature, two definitions, involving a
narrow (∼20Å) and a wide (∼40Å) central bandpass, were measured.
These four new Balmer indices augment 21 indices previously determined
by Worthey et al., and polynomial fitting functions that give index
strengths as a function of stellar temperature, gravity, and [Fe/H]
are provided. The new indices are folded into models for the
integrated light of stellar populations, and predictions are given for
single-burst stellar populations of a variety of ages and
metallicities. Contrary to our initial hopes, the indices cannot break
a degeneracy between burst age and burst strength in poststarbust
objects, but they are successful mean-age indicators when used with
sensitive metallicity indicators. An appendix gives data, advice, and
examples of how to transform new spectra to the 25-index Lick IDS
system.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 87 455 Index measurements
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD ? Henry Draper (Cat. III/135) number
7- 8 A2 --- m_HD Multiplicity index on HD
11- 25 A15 --- Other1 First alternate star name
27- 36 A10 --- Other2 Second alternate name
39- 44 F6.2 0.1nm HdeltaA *? Index equivalent width
47- 52 F6.2 0.1nm HgammaA *? Index equivalent width
55- 60 F6.2 0.1nm HdeltaF *? Index Equivalent width
63- 68 F6.2 0.1nm HgammaF *? Index equivalent width
71- 72 I2 --- NdA Number of HδA measurements
75- 76 I2 --- NgA Number of HγA measurements
79- 80 I2 --- NdF Number of HδF measurements
83- 84 I2 --- NgF Number of HγF measurements
87 I1 --- Qual *Quality
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Note on HdeltaA, HgammaA, HdeltaF, HgammaF:
The "A" means that the wider (∼40Å) definition measures most of the
absorption present in A stars, and the narrower (∼20Å) "F" definition
catches most of the absorption of an F star but very little of the very wide
profile of an A star.
Spectra for HR 296, HR 1726, HR 2047, HR 2503, and HR 2506 were lost
subsequent to Faber et al. (1985ApJS...57..711F 1985ApJS...57..711F), and do not appear in this
table. Most other missing data are due to the spectrograph settings in some
runs that excluded the bluest parts of the spectrum. Other data were deleted
if irregularities were present in the spectra.
Note on Qual:
The quality parameter is normally one, but is 2 if the errors are
judged about twice as large as the value in Table 1 of the printed
paper, and 3 if the errors are judged three times the Table 1 value
or larger.
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Origin: AAS CD-ROM series, Volume 9, 1997 Lee Brotzman [ADS] 25-Jul-97
(End) [CDS] 06-Feb-1998