CDROM/APJS/V111/P377 Hgamma & Hdelta Absorption Features (Worthey+ 1997) ================================================================================ Hgamma and Hdelta Absorption Features in Stars and Stellar Populations Guy Worthey and D. L. Ottaviani <1997, ApJS, 111, 377> =1997ApJS..111..377W ================================================================================ Abstract: The Hgamma and Hdelta 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 (~20 A) and a wide (~40 A) 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. Keywords: galaxies: evolution -- galaxies: stellar content -- line: profiles -- stars: abundances File Summary: -------------------------------------------------------------------------------- File Name Lrecl Records Explanations -------------------------------------------------------------------------------- table2.dat 59 49 Index measurements -------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1-10 A10 --- HD Henry Draper number 11-26 A16 --- Other1 First alternate star name 27-36 A10 --- Other2 Second alternate name 37-44 F8.2 0.1nm HdeltaA *[]? Index equivalent width 45-52 F8.2 0.1nm HgammaA *[]? Index equivalent width 53-60 F8.2 0.1nm HdeltaF *[]? Index Equivalent width 61-68 F8.2 0.1nm HgammaF *[]? Index equivalent width 69-72 I4 --- NdA Number of HdeltaA measurements 73-76 I4 --- NgA Number of HgammaA measurements 77-80 I4 --- NdF Number of HdeltaF measurements 81-84 I4 --- NgF Number of HgammaF measurements 85-87 I3 --- Qual *Quality -------------------------------------------------------------------------------- Notes for file: table2.dat -------------------------------------------------------------------------------- HdeltaA, HgammaA, HdeltaF, HgammaF: The "A" means that the wider (~40 A) definition measures most of the absorption present in A stars, and the narrower (~20 A) "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. 1985, ApJS, 57, 711, 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. 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. -------------------------------------------------------------------------------- ================================================================================ (End) Lee Brotzman [ADS] 25-Jul-97