Hydrogen Lines in DA White Dwarfs: Improved Stark Broadening

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Hydrogen Lines in DA White Dwarfs Improved Stark
Broadening
Pier-Emmanuel Tremblay Pierre
BergeronUniversité de Montréal
E
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Hydrogen-line (DA) white dwarfs
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Spectroscopic Technique Bergeron et al. (1992)
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Photosphere at 20,000 K
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Mihalas, Hummer Däppen 1988Occupation
probability formalism
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Mihalas, Hummer Däppen 1988Occupation
probability formalism
T10,000 K
T20,000 K
charged - neutral
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W
WD0205250"old models" priorto 1992
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Mike Seaton (1990) MHD88 effects should also be
included in line profiles calculations. Bergeron
(1993) ad-hoc parameter, used in all codes
(TLUSTY)
VCS ßcritx2
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Stark Broadening - Hydrogen
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Constant Electric FieldLinear Stark Effect
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Microfield Distribution

• ßE/Eo
• P(ß)dß

MHD88 Holtsmark Nayfonov (1999) Hooper
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rRdebye
Vidal, Cooper Smith (1973)Lemke (1997)
v
?(H)
e-
?
Constant Electric FieldLinear Stark Effect
H
?(e)
rRmin
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Non-adiabatic quantum calculations
n5
n4
electronic collisions no-quenching
n3
n2
n1
t
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V(r) qEz
Hydrogen Atom V(r)
V(z)
V(z)
z
z
Saddle point
?E
Energy of Nth level
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Mihalas, Hummer Däppen 1988Occupation
probability formalism
Bound state
Free State
?E
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ßcrit value not arbitrary!

• ?crit

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

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

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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.

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VCS This Work M. Seaton
(Lemke 1997)
T10,000 K Log Ne 17
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Wiese et al. (1972)
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0.7 M?
0.55 M?
0.7 M?
0.55 M?
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0.7 M?
0.55 M?
0.7 M?
0.55 M?
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?Teff 100 K ?log g 0.06
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GD71
HZ43
This work VCS ßcritx2
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Independent constraints
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40 Eri B
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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.