Do We Understand the PN K 4-47?
Photoionization x Shock-Excitation
Denise R. Gonçalves
Instituto de Astrofísica de Canarias
(IAC - Spain)
Collaborators:
R. Corradi (ING)
A. Mampaso (IAC)
M. Perinotto (U. di Firenze)
A. Riera (U. de Catalunya)
L. López-Martín (IAC)
Main (Large-Scale) Components of PNe
halo
rim
The rim is the result of the interaction
between the fast and slow winds.
The density structure of the attached
shell is determined by the ionization
front.
attached shell
The halo is ionized AGB matter, and
its edge is the signature of the last
thermal pulse.
Rims, shells and haloes are better
identified in the [OIII] and Hα
emission lines.
NGC 2022
Microstructures (LIS) of PNe
- very prominent in the low-ionization lines – [OII], [NII] and [SII];
- fainter in Hα;
- almost absent in [OIII].
(Corradi et al.`00)
(Corradi et al.`97)
NGC 6337
IC 4593
[OIII] [NII]
(Corradi et al.`99)
NGC 6826
K 1-2
[OIII] [NII]
(Balick et al.`98)
[OIII] [NII]
The Morphology and Kinematics of K 4-47
NOT data
(Corradi et al.`00)
K 4-47
Knot1
Core
[OIII] 5007Å
[NII] 6583Å
Knot2
Radial velocities:
Velocity separation (Knot1, Knot2):
105 kms-1 (Hα) and 115 kms-1 ([NII]).
Its kinematics is similar to that of the H-H
objects. Using planar and bow-shock
models of Hartigan et al. `87
=> Vexp = 150 – 200 kms-1
These high-velocity (highly supersonic) knots are likely to be shock excited!
The Morphology and Kinematics of K 4-47
NOT data
(Corradi et al.`00)
K 4-47
Knot1
Core
[OIII] 5007Å
[NII] 6583Å
INT – optical long-slit spectra (P.A.=41°):
- 3700Å to 6750Å
- 3.3Å/pix
- 0¨.70/pix
Knot2
Radial velocities:
Velocity separation (Knot1, Knot2):
105 kms-1 (Hα) and 115 kms-1 ([NII]).
Its kinematics is similar to that of the H-H
objects. Using planar and bow-shock
models of Hartigan et al. `87
=> Vexp = 150 – 200 kms-1
These high-velocity (highly supersonic) knots are likely to be shock excited!
(Gonçalves et al ´04)
Ne, Te and Main
Excitation
Knot1
Knot2
Core
Knot1
Ne and Te
Core
Knot2
Ne[SII] (cm-3)
4600 ±800
1900 ±400
2400 ±400
Te[NII] (K)
18900±2900
>21000
16900±2800
Te[OIII] (K)
>21000
19300 ±2300
16100±4400
(Gonçalves et al. `04)
Te are very high (104K, typical for PNe)!
⇒ the Core is mainly photoionized!
Core is analysed using CLOUDY.
⇒ the high-velocity knots
Knot1 and Knot2 are mainly shock heated!
Knots are modeled using MAPPINGS Ic.
Core: Pure Photoionization
He/H
Core
O/H
1.39E-1(14%) 7.37E-5(32%)
Type-I 1.3±0.018
(4.93 ±2.22)E-4
N/H
3.74E-4(40%)
Ne/H
1.74E-5(66%)
S/H
1.96E-6(48%)
(5.32 ±3.34)E-4 (1.25 ±0.63)E-4 (8.08 ±6.19)E-6
From O, Ne and S (and the large height on the Galactic plane)
⇒ halo PN, Peimbert´s Type-IV.
From He and N => extreme bipolar PN, Peimbert´s Type-I.
CLOUDY Inputs:
i) shape and intensity of the
radiation source;
ii) chemical composition;
iii) geometry, size and density.
CLOUDY Output: the “observe spectrum”
after correction by extinction.
Core Inputs
D (kpc)
Size (")
Ne (cm-3)
Teff (K)
L (Lsolar)
Dust grains
5.9
1.9 (opt)/0.25(radio)
Chemistry
Type-I PN
1900 (opt) up to 3E+5(radio)
120 000 K
550
ISM graphite + silicate
(Gonçalves et al. `04)
Important lines for diagnosis are well
reproduced ([NII], [SII], [OII], [OIII],
HeI, HeII, etc)!
The [OIII] 4363Å and [NII] 5755Å
are largely underestimated
(by a factor around 3) !
This model implies a Core size of
4" (twice the optical size) !
Core: Pure Photoionization
He/H
Core
O/H
1.39E-1(14%) 7.37E-5(32%)
Type-I 1.3±0.018
(4.93 ±2.22)E-4
N/H
3.74E-4(40%)
Ne/H
1.74E-5(66%)
S/H
1.96E-6(48%)
(5.32 ±3.34)E-4 (1.25 ±0.63)E-4 (8.08 ±6.19)E-6
From O, Ne and S (and the large height on
the Galactic plane)
Solution:
⇒ halo PN, Peimbert´s Type-IV.
a strong density stratification!
From He and N => extreme bipolar PN, Peimbert´s Type-I.
An inner core of extremely high density (3 10+5 cm-3) and
CLOUDY Inputs:
CLOUDY
Output:Nethedetermined
“observe spectrum”
an outerofzone
the empirical
from
i) shape and intensity
the matchingafter
correction
by
extinction.
the [SII] lines (2000 cm-3).
radiation source;
ii) chemical composition;
Important lines for diagnosis are well
iii) geometry, size and density.
reproduced ([NII], [SII], [OII], [OIII],
HeI, HeII, etc)!
Core Inputs
D (kpc)
Size (")
Ne (cm-3)
Teff (K)
L (Lsolar)
Dust grains
5.9
1.9 (opt)/0.25(radio)
Chemistry
Type-I PN
1900 (opt) up to 3E+5(radio)
120 000 K
550
ISM graphite + silicate
(Gonçalves et al. `04)
The [OIII] 4363Å and [NII] 5755Å
are largely underestimated
(by a factor around 3) !
This model implies a Core size of
4" (twice the optical size) !
Knots: MAPPINGS Bow-Shock Model
Bow-shock models are successful when applied to
H-H objects (Hartigan et al. `87; Beck et al. `04).
MAPPINGS Ic (Dopita et al. `84; Binette et al. `85).
Te[SII]
Knot1
Knot2
Vbol, to the right,
from 50 to 300 kms-1
Te[NII]
Te[OIII]
MAPPINGS INPUTS:
i) pre-ionization;
ii) chemical composition;
iii) geometry, size and density.
MAPPINGS Output: the “observe
spectrum” after correction by
extinction.
Knots move with 250 – 300 kms-1
They have Type-I PN abundances
Knot´s Te[NII] = 17800 K
The [OIII] (4959Å/4363Å) ratio is
underestimated by 30% (Knot1)
and 70% (knot2).
Caution: the pre-photoionization of the
knots was not considered!
(Gonçalves et al. `04)
Although our modeling pure photoionization for the core, and
pure shock excitation for the pairs of knots
…Do provide important clues…
PHOTO: He and N typical of Type-I (Galactic disk) and an
extreme O deficiency typical of the Galactic halo;
- However, these abundances would not be valid, if the strong density stratification is proved…
and also the Te [NII](6583Å/5755Å)
[OIII](4959Å/4363Å)
would be wrong, as the auroral and nebular lines involved would be formed in
different regions.
Note that, although unusual, such high density cores were found in other highly
collimated PNe (Corradi et al. ’95).
SHOCKS: K 4-47 is one of the few PNe in which the presence of shock-excited features
is confirmed (M 2-48, M 2-16, KjPn 8; Gonçalves ’03).
Note that, very interestingly, its H2 emission is shock-exited –despite the fact that in most
PNe the H2 is excited by fluorescence (Lumsden et a. ’01).
Do we understand the PN K 4-47?
Not really…
because
photoionization
shock
Although our modeling pure
photoionization
for theand
core,
andheating are likely to be
simultaneously present
a real excitation
nebula. Suck
pureinshock
for analysis
the pairs needs:
of knots
⇒ more sophisticated codes that are not available;
provideofimportant
clues…
⇒ to be supported by the…Do
knowledge
the nebular
and stellar parameters.
PHOTO: He and N typical of Type-I (Galactic disk) and an
extreme O deficiency typical of the Galactic halo;
- However, these abundances would not be valid, if the strong density stratification is proved…
and also the Te [NII](6583Å/5755Å)
[OIII](4959Å/4363Å)
would be wrong, as the auroral and nebular lines involved would be formed in
different regions.
Note that, although unusual, such high density cores were found in other highly
collimated PNe (Corradi et al. ’95).
SHOCKS: K 4-47 is one of the few PNe in which the presence of shock-excited features
is confirmed (M 2-48, M 2-16, KjPn 8; Gonçalves ’03).
Note that, very interestingly, its H2 emission is shock-exited –despite the fact that in most
PNe the H2 is excited by fluorescence (Lumsden et a. ’01).
Shock excitation in other PNe with LIS
Dwarkadas & Balick `98 X Soker & Reveg `98 (instabilities; evolution)
None of the high-velocity pairs of LIS, imaged with HST, show either
bow-shock structures or shock excitation.
But, actually...
FLIERs and SLOWERs of NGC 7662, analysed with the WFPC2 and STIS,
are similar in terms of density contrast and main excitation mechanism.
NO SHOCK-EXCITED LIS WERE FOUND! Perinotto et al. `04
One problem with at least two possible solutions…
First: shock excitation in young PNe
M 1-16
M 2-48
Hα
[NII]
C
B
A
(Schwarz `99; Huggins et al. `00)
-This is a young PN in with
multiple ejections and with
line ratios characteristic of
shock-excited emission
(Schwarz `92).
Data from 2.2 and 3.5m telescopes
(Vázquez et al. `99)
-The pairs of knots are also
shock-excited.
Data from 2.1 and 2.2m telescopes
M 1-16 and M 2-48 are very similar to K 4-47:
- highly collimated bipolar PNe;
- with high-velocity structures (100 up to 300 km/s);
However, NGC 7009 seems to be more evolved
them M 1-16, M 2-48 and K 4-47.
⇒ So, shock excitation can be found, with small and
medium telescopes, but only associated with less
evolved PNe! Note that PNe have weak shocks…
Second: can large telescopes prove whether or
not evolved PNe have weak
(Perinotto et al. `04)
shocks?
⇒ NGC 7662 (STIS) is the PNe with FLIERs analyzed
with the highest spatial resolution;
But Perinotto et al. argue “the perhaps the thickness of the
shocked layer in FLIERs is too small to be resolved, even
with HST…in spite of the brightness of the nebula”!
⇒ We do not know the size of the shocked zone (or the
thickness of the working surface associated to the
shock), simulation are under development (Leiden
Group)…
STIS spatial scale: 0.1x0.2 arcsec;
0.05x0.05 arcsec
Could the NGST, the VLTI, with mas spatial scale, resolve shocks of evolved PNe?
Perhaps even SALT, GEMINI, … could resolve these shocks…
K 4-47’s Line Profiles
K 4-47
INT – long-slit spectra:
- 3700Å to 6750Å
⇒ LIS´s excitation;
- 3.3Å/pix
⇒ LIS´s chemical abundances. - 0¨.70/pix
⇒ LIS´s Te and Ne;
Knot1
Core
[OIII] 5007Å
[NII] 6583Å
Knot2
K 4-47 has a pair of lowionization jets or a pair of
knots (the tips of the jets).
(Gonçalves et al.`01)