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 !!!