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Hot Gas in Planetary NebulaeHot Gas in Planetary Nebulae
You-Hua ChuYou-Hua Chu Robert A. Gruendl Robert A. Gruendl Martín A. Guerrero Martín A. Guerrero Univ. of Illinois Univ. of Illinois
Hot Gas Expected in Interacting Winds
Fast wind is shocked to 107 - 108 KHot gas in bubble interior 106 KConduction layer 105 K
Complications and Problems
• Fast stellar wind - isotropic? collimated? - constant velocity? - constant mass loss rate?
• Mixing with nebular gas - thermal evaporation - dynamic ablation - presence of magnetic field
• Non-equilibrium ionization - abundance, temperature, mass
When we can’t get potatos, we eat yams…
(massive star bubbles)
Interstellar and Circumstellar Bubbles
Low-mass RG, AGB CSPN
Slow wind Fast wind
Circumstellar Circumstellar
nebula bubble
Interstellar
bubble
Slow wind Fast wind
Massive RSG, LBV WR
Circumstellar Bubble NGC 6888
Chandra X-ray Image of NGC 6888
R: H G: [O III] B: X-rayGruendl, Guerrero, Chu 2003, in prep.
Circumstellar Bubble S308
XMM-Newton X-ray Image of S 308
HD 50896
* R: H G: [O III] B: X-rayChu et al. 2003, submitted
X-ray Spectra of Hot Gas in WR Bubbles
NGC 6888 (Chandra) S 308 (XMM)
X-ray Observations of Shocked Fast Wind
• Detection of hot gas associated with fast winds - 6 PNe, 2 WR bubbles, 2 superbubbles*
• Properties of the hot gas:
Te [106 K ] Ne [cm-3 ] LX [erg/s]
PN 2-3 106 100 1031 1032
WR 1-2 106 1 1034
SB 8 106 0.1 1033
(* Townsley et al. 2003, ApJ, in press - Rosette & Omega)
Pressure-driven bubble with heat conduction at interface
Lx (obs) / Lx (expected) = 10-1 to 10-3
Adjust fast wind- wind velocity- mass loss rate
Reduce heatconduction
Dynamically mix nebular material
More observations are needed.
and potato skins…
(105 K gas at the interface)
FUSE - Nebular OVI Absorption IC 418NGC 2392
Stellar P Cygni profile; nebular O VI absorption
H H
1037
1032
1037
1032
FUSE - Nebular OVI Emission
NGC 7009 NGC 6543
Stellar P Cygni profile; nebular O VI emission
Inside
Outside
Star
1032 1037
FUSE - Nebular OVI Emission
NGC 7293 NGC 3132
No stellar P Cygni profile; No nebular O VI emission
10371032
O IO IC II
Star
Inside
Hot gas is cool !!!