Stark Broadening of Carbon and Oxygen Lines in Hot DQ White Dwarf Stars: Recent Results and Applications

Abstract

White dwarf stars are traditionally found to have surface compositions made primarily of hydrogen or helium. However, a new family has recently been uncovered, the so-called Hot DQ white dwarfs, which have surface compositions dominated by carbon and oxygen with little or no trace of hydrogen and helium (Dufour et al. 2007(Dufour et al. , 2010. Deriving precise atmospheric parameters for these objects (such as the effective temperature and the surface gravity) requires detailed modeling of spectral line profiles. Stark broadening parameters are of crucial importance in that context. We present preliminary results from our new generation of model atmosphere including the latest Stark broadening calculations for CII lines and discuss the implications as well as future work that remains to be done.

On the Stark broadening of Cr VI spectral lines in astrophysical plasma

“…Spectral lines of highly charged chromium ions, including Cr VI, have been observed in the spectra of white dwarf atmospheres where, as it has been demonstrated several times [12,13,14,15,16,17,18,19,20,21,10], Stark broadening is usually dominant line broadening mechanism. With the results obtained here, we also wish to demonstrate the importance of Stark broadening in DO white dwarf atmospheres, which effective temperature is within the range 40 000 K < T ef f < 120 000 K.…”

Stark broadening of B iv spectral lines

“…Lanz et al (1988); Popović et al (1999a); Popović et al (1999b); Popović et al (2001a,b); Tankosić, Popović & Dimitrijević (2003); Simić et al (2005a,b)). In white dwarfs, especially Stark broadening is the dominant collisional line broadening mechanism in all important layers of the atmosphere (Popović et al 1999b;Tankosić, Popović & Dimitrijević 2003;Milovanović et al 2004;Simić et al 2006;Dimitrijević et al 2011;Dufour et al 2011;Larbi-Terzi et al 2012;Simić, Dimitrijević & Sahal-Bréchot 2013;Simić, Dimitrijević & Popović 2014). The theory of Stark broadening is well applied, especially for accurate spectroscopic diagnostics and modelling.…”

On the stark broadening of Ar VII spectral lines

“…An important topic where Stark broadening data are needed are astrophysical plasmas (Beauchamp et al, 1997;Dimitrijević & Sahal-Bréchot, 2014b ), in particular at mospheres of white dwarfs, pre white dwarf stars, and post AGB (Asymptotic Giant Branch) stars (Tankosić et al, 2003;Milovanović et al, 2004;Simić et al, 2006;Dufour et al, 2011). Additionally, since for temperatures higher than around 10 000 K hydrogen is mainly ionized, Stark broadening is, in such a case, the principal pressure broadening mechanism (Griem, 1974).…”