- + Hydrogen Lines in DA White Dwarfs: Improved Stark Broadening E Pier-Emmanuel Tremblay & Pierre Bergeron Université de Montréal

Hydrogen-line (DA) white dwarfs

Spectroscopic Technique : Bergeron et al. (1992)

Photosphere at 20,000 K

Mihalas, Hummer & Däppen 1988 Occupation probability formalism

charged - neutral T=10,000 KT=20,000 K

W WD "old models" prior to 1992

Mike Seaton (1990) : MHD88 effects should also be included in line profiles calculations. Bergeron (1993) : ad-hoc parameter, used in all codes (TLUSTY) VCS β crit x2

Stark Broadening - Hydrogen

Constant Electric Field Linear Stark Effect

Microfield Distribution β =E/E o P( β )d β MHD88 : Holtsmark Nayfonov (1999) : Hooper

H e-e- v r=R debye r=R min Ψ(H) Ψ(e) ρ Vidal, Cooper & Smith (1973) Lemke (1997) Constant Electric Field Linear Stark Effect

t n=1 n=2 n=3 n=4 n=5 Non-adiabatic quantum calculations electronic collisions no-quenching

Hydrogen Atom : V(r) V(r) + qEz V(z) z z Saddle point ΔEΔE Energy of Nth level

ΔEΔE Bound state Free State Mihalas, Hummer & Däppen 1988 Occupation probability formalism

β crit value not arbitrary! Βcrit } electronic collisions

Seaton (1990) Low Fields High Fields Seaton (1990) : first non-ideal profiles using approximate electronic broadening profiles Bergeron (1993) : ad-hoc parameter.

This work Vidal, Cooper & Smith (1973) electron broadening theory. Non-ideal correction for proton perturbations (MHD 88, Seaton 90).

This work Non-ideal correction for electron perturbations (MHD 88). It accounts for about 10% of the non-ideal effects. Consistent implementation of the MHD88 Theory.

T=10,000 K Log Ne =17 VCS This Work M. Seaton (Lemke 1997)

Wiese et al. (1972)

0.55 M  0.7 M  0.55 M 

0.7 M  0.55 M 

ΔTeff =+100 K Δlog g = +0.06

GD71 HZ43 This work VCS β crit x2

Independent constraints

40 Eri B

Conclusion Spectroscopic technique (Bergeron et al. 1992). Current model atmospheres use MHD88 EOS and VCS Stark broadening profiles (Lemke 1997 tables) Here we add MHD88 inside the VCS broadening theory in a consistent way for the first time. We are currently looking at further implications at low and high T eff, UV lines and DO white dwarfs.