Background Opacities

¹ Space Telescope Science Division of ESA, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
² Kapteyn Institute, PO Box 800, 9700 AV Groningen, The Netherlands

Abstract

In NLTE computations of trace elements in stellar atmospheres, background opacities are generally treated in LTE. It is thus important to assess the impact of different methods of including this background opacity on the statistical equilibrium of the trace element and its resulting NLTE abundance. This article illustrates these effects using two examples, nitrogen in Vega and carbon in the Sun.