STARS: ABUNDANCES; POPULATION II; GALAXY: ABUNDANCES
Abstract :
[en] A detailed analysis of neutral iron lines in a sample of 13 metal-poor dwarfs and subgiants is carried out on the basis of high resolution spectra obtained with the ESO Coude Echelle Spectrometer. The deduced iron abundance is found to depend on the excitation potential of the line used, higher excitation lines generally indicating higher abundances. This could be caused by departures from the local thermodynamic equilibrium (LTE) or by temperature inhomogeneities in the stellar atmospheres. The dependency of this effect on the stellar atmospheric parameters is investigated. From the comparison of iron lines with lines of other elements, it is concluded that the low excitation FeI lines are much more affected than the high excitation lines. The consequences of these effects for the classical abundance analyses are examined. It is found that they may explain, at least in part, some previously reported discrepancies between the results of different authors.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Magain, Pierre ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Zhao, G.
Language :
English
Title :
Empirical study of departures from the excitation equilibrium of FeI in metal-poor stars.