Influence of NLTE calculations on the hydrogen lines in chromospheric models

¹ Hamburger Sternwarte, University of Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
² St. Mary's University, Halifax, NS B3H 3C3, Canada e-mail: bfuhrmeister@hs.uni-hamburg.de

Received: 7 July 2005
Accepted: 3 March 2006

Abstract

We present extensive NLTE calculations for a semi-empirical solar 1D chromosphere model based on the VAL C model. We report on a significant influence of nitrogen, oxygen, and sulfur on the emergent hydrogen emission with respect to LTE vs. NLTE calculations for these elements. Moreover, we present a model spectrum with 20 light and iron group elements computed in NLTE. We compare this to an observed solar spectrum and to a photospheric model spectrum. We find that the agreement for this model with the data is less good than the original VAL C model especially in the UV. This may imply the need of changes in the chromospheric temperature structure or may point to general problems of static 1D chromospheric models.