the dynamical evolution of planetary nebulae · 2015. 12. 2. · 70 yr 535 yr 1290 yr 1690 yr 1925...
TRANSCRIPT
The Dynamical Evolution of
Planetary Nebulae
D. Schonberner
Leibniz-Institut fur Astrophysik Potsdam (AIP)
In cooperation with M. Steffen, R. Jacob, & R. L. M. Corradi
• The physical system & its modelling
• Expansion velocities
– PNe of the Galactic disk
– Metal-poor PNe
• Soft X-ray emission
• Summary
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 1/22
The physical system (1)
Planetary Nebula:Relic of AGB wind, re-shaped by the steadily changingradiation field & wind of the post-AGB (= central) starwhile evolving across the HRD towards the WD stage
NGC 6826 AGB
♦ 103 yrs
3 M�
0.6 M�
RGB
Double-shellburning
Last TP cycle:strong mass lossterminatesevolution!
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 2/22
The physical system (2)
A typical round/elliptical PN –
Central star: Teff ' 100 000 K
Size of PN: Rpn ' 0.2 pc
⇒ kinematic PN age: ' 8 000 yr
Size of halo: Rhalo ' 0.6 pc
⇒ kinematic halo age: ' 40 000 yr
Halo –
Record of very final loss of stellar matter,enriched by freshly synthesized elementsdredged-up from the stellar interior bymixing processes
Planetary Nebula proper –
c© R. Corradi
2 nested shells: Bright RIM & attached fainter, much more massive SHELL,enclosing a “hole/cavity” containing the central star, and expanding
into the halo
⇒ A dynamical system with time-dependent boundary conditions !
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 3/22
The physical system, schematic (3)
Physical structure of a Planetary Nebula
fast
wind
hot
Bubble
106 .. 108 K
inner wind shock
Contact discontinuity
Rim 104 K
PN shaped by
colliding winds
fast central star wind
ÃÄ slow AGB wind
photoionization
by UV radiation
of hot central star
Slow
AGB
wind
Slow
AGB
wind
Shell 104 K outer shock
oute
r sh
ock
c© M. Steffen, AIP
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 4/22
Historical summary (1)
Early attempts – Matthews 1966, Ferch & Salpeter 1975
Expansion of a shell with initially ad hoc constant densityand velocity into vacuum, stellar radiation field constant
⇒• No sharp outer boundaries, shells disperse
• Backfill if no stellar wind (or radiation pressure on grains) for support
Authors claim fair agreement with observations, thoughno observables have been computed for comparisons !
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 5/22
Historical summary (2)
A breakthrough – Kwok, Purton & Fitzgerald 1978
Birth of the interacting stellar winds (ISW) theory⇒
• Fast, tenuous central-star wind sweeps-up slow, dense relic of AGB-wind
• Natural consequence is one nebular shell expanding into and engulfingupstream AGB-wind material (= halo, if ionised)
Kwok 1982/1983:
Stellar evolution considered, i.e. time-dependent stellar winds& radiation fields ⇒ Shells expanding with '20 km s−1 possible
BUT:Analytical solutions, thus hydrodynamics due to ionisation
could not be considered properly
Chu et al. 1987, based on deep CCD imaging of PNe:
PNe generally with double-shell structure (triple with halo)
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 6/22
Historical summary (3)
Modern simulations –
Schmidt-Voigt & Koppen 1989:• 1st radiation-hydrodynamics (RHD) study with time-dependent
ionisation of H & He, recombination discussed• Ad hoc initial shells around evolving central-star models (Schonberner),
simple wind model• Ionisation + stellar wind ⇒ double-shell structure, as observed!
Marten & Schonberner 1991: Like above but with better wind model
Mellema 1994/1995 . . . (& coauthors):• Better numerics, evolving & non-evolving stars, 1D & 2D (!)
Schonberner et al. 1997: & follow-up Papers I–VIII, 2004–2013• 1st consistent RHD simulation up the AGB & across the PN region
towards the white-dwarf stage, with a detailed mass-loss prescription• Time-dependent ionisation, recombination, heating & cooling for
Villaver et al. 2002:• Consistent RHD simulations based on mass-loss & AGB/post-AGB
models of Vassiliadis & Wood (1994)• No time-dependent ionisation, heating or cooling
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 7/22
Simulations (1a)
Consistent modelling the evolution of Star & wind envelope
5.5 5.0 4.5 4.0 3.5log Teff/K
2.0
2.5
3.0
3.5
4.0
log
L/L O •
ages in 103 yrs
025
10
15
0 5 10 15Post-AGB age [103 yr]
-2
0
2
4
log
L/L O •
L <912
Lbol
Lwind
10-1110-10
10-9
10-8
10-7
10-6
dM/d
t [M
O • /y
r] Reimers
Pauldrach et al.
0 5 10 15Post-AGB age [103 yr]
101
102
103
104
105
V [k
m/s
]
0.595 M�
1D-hydrodynamics of circumstellar envelope with time-dependent physics
• ionisation, recombination, heating, cooling for 9 elem., 12 ion. stages
• inner boundary condition (ri = 5×1014 cm):
– Star radiates as a black body with Teff(t)
– V∞(t), ρi(t) ∼ M(t)/r2i /V∞(t) from the wind model
Comput. of observables: line strengths & profiles, intensity distributions,X-ray emission (heat conduction incl.)
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 8/22
Simulations (1b)
5.5 5.0 4.5 4.0 3.5log (Teff / K)
2.5
3.0
3.5
4.0
log (
LC
S / L
O • )
0.696 MO • ,
0.625 MO • ,
0.605 MO • ,
0.595 MO • ,
0.585 MO • ,
0.836 MO • ,
0.565 MO • ,
70 yr
535 yr1290 yr1690 yr1925 yr
90 yr
2930 yr
time marks @ {0.3, 1, 3, 10, 30}x103 yr
The post-AGB tracksused for the simulations –
Post-AGB evolutionextremely sensitiveto remnant masses interms of luminosity &
time scale
Limiting luminosity fora '0.6 M� remnantwithin 30 000 years:'125 L�
RHD simulations for
• various post-AGB remnamts: 0.565. . . 0.696 M�• various initial envelope config., e.g. ρ ∝ r−α, α = 2, . . .3.5,
& by hydrodynamics of dusty AGB winds
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 9/22
Simulations (2a)
Match between models & real objects – No fits aimed at!
Young model:0.595 M�,age = 3364 yr,Teff = 39 300 K
rim
shell
Shell (or I-shell) bright in in Hα or [N II]
Rim (or W-shell) bright in [O III]
PN structure mainly determined by ionisation !
Winds interaction still not dominant !
NOTE: V[N II] > V[O III]
for young, optically thick PNe !
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 10/22
Simulations (2b)
Doppler-velocities V[N II] vs. V[O III] Jacob et al. 2013 (Paper VIII)
-2 0 2 4
0
1
2
3
4
V [N
II] /
V [O
III]
6 7 8
MV
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
0
1
2
3
4
-2 0 2 4
0
1
2
3
4
V [N
II] /
V [O
III]
6 7 8
MV
0.585 MO • , α=2.5
0.595 MO • , α=3
0.595 MO • , Hydro
0.605 MO • , Hydro
0.625 MO • , α=2
0.696 MO • , α=2
Cool luminous stars hot, faint starsOpt. thick PNe opt. thick PNe
Objects from thelocal sample of
Frew 2008
Open symbols:D ≤ 1 kpc
Filled symbols:D > 1 kpc
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 11/22
Simulations (3)
Match between models & real objects – No fits aimed at!
Middle-aged model:0.595 M�,age = 6100 yr,Teff = 80 200 K
density / velocity
0 2 4 6 8r [1017 cm]
0
500
1000
1500
2000
2500
n [c
m−3
]
0
20
40
60
80
V [k
m/s
]
surface brightness
0
0.5
1.0
I/Im
ax
[O III]
line profiles
0
0.5
1.0
I/Im
ax
[O II
I] 5
007
Å
0 2 4 6 8r [1017 cm]
0
0.5
1.0
I/Im
ax
[N II]
−40 −20 0 20 40V [km/s]
0
0.5
1.0
I/Im
ax
[N II
] 65
83 Å
rim
shell
halo
RPNC D
Mrim = 0.07 M�, ISW !Mshell = 0.40 M�, ionisation !
0.0
0.2
0.4
0.6
0.8
1.0
norm
alis
ed in
tens
ity
[NII] 6583Å
[OIII] 5007Å
−40 −20 0 20 40V [km/s]
0.0
0.2
0.4
0.6
0.8
1.0
norm
alis
ed in
tens
ity
−40 −20 0 20 40V [km/s]
Double-shell structure: rim & shell,despite smooth initial density profile!
Distinct velocities for rim & shell
Again NOT compatible with the Interacting Stellar Winds (ISW) theory!
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 12/22
Expansion velocities (1)
What is the true expansion velocity of a planetary nebula?
The position of the shell’s shock defines the nebular radius, RPN
⇒ This shock’s propagation speed, RPN, is the true PN expansion velocity
However,
the shock velocity cannot be measured spectroscopically!
Measurable “expansion” velocities are:
1. Peak separation of Doppler split emission lines (= Vrim)
2. Half width of emission lines of spatially unresolved objects
3. Post-shock velocity Vpost = RPN/F , with F > 1, Corradi et al. 2007
Velocities to 1. & 2. may depend (!) on ion used, correspondence to RPN ?A typical mean value used in statistical studies is 20–25 km s−1
Only velocity to 3. is physically sound, independent (!) of the ion used,correction F depends on shock property, = 1.25± 0.05 Jacob et al. 2013
Spectroscop. measured velocity smaller than the true velocity!
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 13/22
Expansion velocities (1a)
Kinematical age 6= post-AGB age, agePN ' tpost−AGB − ttrans
Predictions by our model PNe:
0.81.0
1.2
1.4
1.6
1.8
2.0
2.2
po
st-
AG
B a
ge
/
(R
OU
T /
VP
OS
T)
0.585 MO • , α=2.5
0.595 MO • , α=3
0.595 MO • , Hydro
0.605 MO • , Hydro
0.625 MO • , α=2
0.0
0.5
1.0
1.5
2.0
2.5
3.0
po
st-
AG
B a
ge
/
(R
CD /
VR
IM )
0.00.2
0.4
0.6
0.8
1.0
1.2
1.4
po
st-
AG
B a
ge
/
(R
OU
T /
VR
IM )
4.6 4.8 5.0 5.2log Teff [K]
0.6
0.7
0.8
0.9
1.0
1.1
1.2
po
st-
AG
B a
ge
/
(R
OU
T /
VA
V )
Shell radius/post-shock velocity:
Reasonable, except youngest PNe
Rim velocity/rim velocity:
Underestimated, except youngest PNe
Shell velocity/rim velocity:
Overestimated, except oldest PNe
Shell velocity/average velocity:Gesicki et al. 1998
Reasonable, velocity field must be known!
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 14/22
Expansion velocities (2)
Post-shock velocity of the shell – after Corradi et al. 2007
Example NGC 6862, Inflection point of the (outer) shell line profile
good measure of Vpost:
0.0
0.2
0.4
0.6
0.8
1.0
norm
alis
ed in
tens
ity
[NII] 6583Å
[OIII] 5007Å
−40 −20 0 20 40V [km/s]
−1.0
−0.5
0.0
0.5
1.0
norm
alis
ed d
eriv
ativ
es
−40 −20 0 20 40V [km/s]
Model predictions:
4.6 4.8 5.0 5.2log Teff [K]
1.0
1.1
1.2
1.3
1.4
1.5
RO
UT /
VP
OS
T
. 0.585 MO • , α=2.5
0.595 MO • , α=3
0.595 MO • , Hydro
0.605 MO • , Hydro
0.625 MO • , α=2
Robust value of F = Rout/Vpost:
(optically thin models):
1.25±0.05
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 15/22
Expansion velocities (3)
Results for 22 PNe – Tautenburg/NTT/NOT/CAT
Schonberner et al. 2014
4.5 4.6 4.7 4.8 4.9 5.0log Teff [K]
0
10
20
30
40
50
60
70
V [km
/s]
Vpost
Vrim
Vpost
Vrim
Vpost
Vrim
Vpost
Vrim
IC289
IC289
IC289
IC289
IC289
IC289
IC289
IC3568
IC3568
IC3568
IC3568
IC3568
IC3568
IC4593
IC4593
IC4593
IC4593
IC4593
IC4593
IC4593
IC4593
IC4593
IC4593
M1-4
6M
1-4
6
M2-2
M2-2
M2-2
M2-2
M2-2
M2-2
M2-2
M2-2
M2-2
NG
C2022
NG
C2022
NG
C2022
NG
C2022
NG
C2022
NG
C2022
NG
C2022
NG
C2022
NG
C2610
NG
C2610
NG
C2610
NG
C2610
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C3242
NG
C5882
NG
C5882
NG
C6543
NG
C6543
NG
C6543
NG
C6543
NG
C6629
NG
C6629
NG
C6629
NG
C6629
NG
C6826
NG
C6826
NG
C6826
NG
C6826
NG
C6826
NG
C6826
NG
C6826
NG
C6826
NG
C6884
NG
C6884
NG
C6884
NG
C6884
NG
C6891
NG
C6891
NG
C6891
NG
C6891
NG
C6891
NG
C6891
NG
C7009
NG
C7009
NG
C7009
NG
C7009
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7354
NG
C7662
NG
C7662
NG
C7662
NG
C7662
NG
C7662
NG
C7662
Tc1
Tc1
Vy2-3
Vy2-3
Vy2-3
Vy2-3
IC418
IC418
IC2448
IC2448
NG
C1535
NG
C2610
NG
C7662
My60
My60
My60• Vpost > Vagb (' 10 km s−1),
rapid increase of Vpost
from ≈ Vagb to ' 40 km s−1
• For logTeff <∼ 4.7:
Vrim < Vagb,
then increase of Vrim to
≈ 25–30 km s−1
• Vpost/Vrim can be as large as 6 !
Theoretical expectations:
SHELL: RPN (or Vpost) depends on Te & upstream density gradiente.g. Chevalier 1997
RIM: Vrim is constraint by upstream pressure of ionised/heated shell) &hot bubble pressure (winds interaction) – e.g. Kwok et al. 1978
first deceleration/stalling due to high shell pressure,
then acceleration due to increasing wind power11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 16/22
Expansion velocities (4)
Kinematics of shells –
0
10
20
30
40
50
60
Vp
ost [
km
/s]
MCS = 0.595 MO • , nAGB ~ r - α, VAGB = 10 km/s
MCS = 0.595 MO • , nAGB ~ r - 3, VAGB = 20 km/s
MCS = 0.595 MO • , nAGB & VAGB : hydro sim.
α=2.00
α=2.25α=2.50
α=2.75
α=3.00
α=3.25
α=3.50
4.5 4.6 4.7 4.8 4.9 5.0 5.1log Teff [K]
0
10
20
30
40
50
60
Vrim [km
/s]
α=2.00
α=2.25
α=2.50α=2.75α=3.00
α=3.25
α=3.50
0
10
20
30
40
50
60
Vp
ost [
km
/s]
MCS = 0.595 MO • , nAGB ~ r - α, VAGB = 10 km/s
MCS = 0.595 MO • , nAGB ~ r - 3, VAGB = 20 km/s
MCS = 0.595 MO • , nAGB & VAGB : hydro sim.
α=2.00
α=2.25α=2.50
α=2.75
α=3.00
α=3.25
α=3.50
4.5 4.6 4.7 4.8 4.9 5.0 5.1log Teff [K]
0
10
20
30
40
50
60
Vrim [km
/s]
α=2.00
α=2.25
α=2.50α=2.75α=3.00
α=3.25
α=3.50
0
10
20
30
40
50
60
Vpost [
km
/s]
MCS = 0.595 MO • , nAGB ~ r - α, VAGB = 10 km/s
MCS = 0.595 MO • , nAGB ~ r - 3, VAGB = 20 km/s
MCS = 0.595 MO • , nAGB & VAGB : hydro sim.
α=2.00
α=2.25α=2.50
α=2.75
α=3.00
α=3.25
α=3.50
4.5 4.6 4.7 4.8 4.9 5.0 5.1log Teff [K]
0
10
20
30
40
50
60
Vrim [km
/s]
α=2.00
α=2.25
α=2.50α=2.75α=3.00
α=3.25
α=3.50
Vpost for a model grid withpower-law density profiles, ρ ∝ r−α,with α = 2 . . .3.5, Vagb = 10 km s−1,and for Mcspn = 0.595 M�:
PNe expand into (power-law)environments with initially α ≈ 2.8–3.4
Observed halo intensity distribution,SB ∝ r−γ ?
6 objects in common: 〈α〉 = 3.1± 0.1〈γ〉 = 5.2± 0.2 Schonberner et al. 2014
Since γ ' 2α− 1 ⇒ 〈α(γ)〉 ' 3.1
⇒ Observed post-shock velocities consistent with measured radialdensity profiles of halos
α > 2, ⇒ final mass loss on AGB “accelerated”! 〈RPN〉 ' 45 km s−1
(cf. Kwok, Volk & Hrivnak 2002 on density profiles of dusty envelopes around PPNe, α >∼ 2.5)
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 17/22
Expansion velocties (5)
Kinematics of rims –Sample objects with known Vcspn:
0 1000 2000 3000 4000VCSPN [km/s]
0
10
20
30
40
50
VR
IM [km
/s]
0.585 MO • , α=2.5
0.595 MO • , α=3
0.595 MO • , Hydro
0.605 MO • , Hydro
0.625 MO • , α=2
0
10
20
30
40
50
60
Vp
ost [
km
/s]
MCS = 0.595 MO • , nAGB ~ r - α, VAGB = 10 km/s
MCS = 0.595 MO • , nAGB ~ r - 3, VAGB = 20 km/s
MCS = 0.595 MO • , nAGB & VAGB : hydro sim.
α=2.00
α=2.25α=2.50
α=2.75
α=3.00
α=3.25
α=3.50
4.5 4.6 4.7 4.8 4.9 5.0 5.1log Teff [K]
0
10
20
30
40
50
60
Vrim [km
/s]
α=2.00
α=2.25
α=2.50α=2.75α=3.00
α=3.25
α=3.50
〈Vrim〉 ' 19 km s−1
Vcspn ∝ R−0.5cspn , and for Lcspn = const ⇒ Teff ∝ R−0.5
cspn ⇒ Vcspn ∝ Teff
Increasing stellar wind power, Mcs×V 2cs/2,
⇒ increase of bubble pressure⇒ acceleration of rim, sweep-up of upstream (shell) matter
Theory of radiatively-driven stellar winds predicts correct rim velocities11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 18/22
Expansion velocities (6)
Metal-poor PNe – Final test against the “universality” of the ISW theory!
We expect: Schonberner et al. 2014
• RPN (& Vpost) up if metallicity down because of
higher electron temperatures
• Vrim down if metallicity down because of lower wind power
Observations with VLT/Argus IFU of 4 metal-poor PNe,BoBn 1, M2-29, PRMG 1, Ps 1/K648
0.0
0.2
0.4
0.6
0.8
1.0
norm
alis
ed in
tens
ity
BoBn1 [OIII] 5007Å
M2−29 [OIII] 5007Å
−50 0 50V [km/s]
0.0
0.2
0.4
0.6
0.8
1.0
norm
alis
ed in
tens
itiy
PRMG1 [OIII] 5007Å
−50 0 50V [km/s]
Ps1 [OIII] 5007Å
4.5 4.6 4.7 4.8 4.9 5.0 5.1log Teff [K]
0
10
20
30
40
50
60
70
V [
km
/s]
Vpost
Vrim
Vpost
Vrim
Vpost
Vrim
Vpost
Vrim
4.5 4.6 4.7 4.8 4.9 5.0 5.1log Teff [K]
0
10
20
30
40
50
60
70
V [
km
/s]
BoB
n1
M2−
29
PR
MG
1
Ps1
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 19/22
Soft X-ray emission from PNe (1)“Hot bubble” of shocked stellar wind – filling the central cavityc©Ruiz et al. 2013 0.3–2.0 keV
IC 418:
TX ' 3 MK
LX ' 9×1029 erg/s
NGC 2392:
TX = 2.1 MK
LX = 1.8×1031 erg/s
NGC 6826:
TX = 2.3 MK
LX = 2.0×1030 erg/s
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 20/22
Soft X-ray emission from PNe (2)
Heat conduction – Soker 1994, Steffen et al. 2008
Heat conduction reduces characteristic bubble temperature TX &increases mean bubble density (hence X-ray emission measure)
X−ray Temperature ( 6 − 41 Å) over wind velocity
0 1000 2000 3000 4000 5000 6000Vwind [km/s]
5.5
6.0
6.5
7.0
7.5
log
Tx
[K]
IC 418
NGC 2392
NGC 3242
NGC 6543
NGC 6826
NGC 7009
BD+30
NGC 40
NGC 5315
PN X−ray observationsM=0.696 Mo, HC2M=0.595 Mo, HC2M=0.565 Mo, HC2 T0
adiabaticpost-shock temp.
X−ray luminosity ( 6 − 41 Å) over total luminosity
5.5 5.0 4.5 4.0log(Teff) [K]
−9
−8
−7
−6
−5
−4lo
g(L X
/Lst
ar)
IC 418
NGC 2392
NGC 3242
NGC 6543
NGC 6826
NGC 7009
BD+30
NGC 40
NGC 5315
PN X−ray observationsM=0.696 Mo, HC2M=0.595 Mo, HC2M=0.565 Mo, HC2
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 21/22
SUMMARY
Structure, expansion, & X-ray emission of PNe in generalagreement with predictions of full RHD simulations:
• Double-shell structure a natural consequence of ionisationand winds interaction (no distinct mass-loss events necessary!)
• The expansion of a PN is driven by ionisation,not by the central-star wind alone (as the ISW theory assumes)
• Expansion speed of the nebula’s outer edge depends onelectron temperature & upstream density profile only,
with mean value ' 45 km s−1
• Expansion of the rim driven by central-star wind (ISW !),with mean value ' 20 km s−1
• Mass-loss rate increases along final AGB evolution α ' 3.1
• Metal-poor PNe expand faster (Te ↑), their bright rimslower (Lwind ↓) as compared to the metal-rich counterparts
• Winds interaction important in PNe with WR central stars
• Heat conduction responsible for soft X-ray emission
11th Pac. Rim Conf. on Stellar Astrophys., Hong Kong, Dec. 14–17, 2015 c© D. Schonberner, AIP 22/22