Hydrogen Lines in DA White Dwarfs: Improved Stark Broadening

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

2. Hydrogen-line (DA) white dwarfs

3. Spectroscopic Technique : Bergeron et al. (1992)

4. Photosphere at 20,000 K

5. Mihalas, Hummer & Däppen 1988Occupation probability formalism

6. Mihalas, Hummer & Däppen1988Occupation probability formalism T=10,000 K T=20,000 K charged - neutral

7. W WD0205+250"old models" priorto 1992

8. Mike Seaton (1990) : MHD88 effects should also be included in line profiles calculations. Bergeron (1993) : ad-hoc parameter, used in all codes (TLUSTY) VCS βcritx2

9. Stark Broadening - Hydrogen

10. + + Constant Electric FieldLinear Stark Effect - + + + +

11. Microfield Distribution β=E/Eo P(β)dβ MHD88 : Holtsmark Nayfonov (1999) : Hooper

12. r=Rdebye Vidal, Cooper & Smith (1973)Lemke (1997) v Ψ(H) e- ρ Constant Electric FieldLinear Stark Effect H Ψ(e) r=Rmin

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

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

15. Mihalas, Hummer & Däppen 1988Occupation probability formalism Bound state Free State ΔE

16. βcrit value not arbitrary! Βcrit }electronic collisions

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

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

19. 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.

20. VCSThis WorkM. Seaton (Lemke 1997) T=10,000 K Log Ne =17

21. Wiese et al. (1972)

23. 0.7 M 0.55 M 0.7 M 0.55 M

24. 0.7 M 0.55 M 0.7 M 0.55 M

26. ΔTeff =+100 KΔlog g = +0.06

27. HZ43 GD71 This work VCS βcritx2

28. Independent constraints

29. 40 Eri B

30. 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 Teff, UV lines and DO white dwarfs.