Physical conditions of the shocked regions in collimated outflows of planetary nebulae

Angels Riera (UPC)

OUTLINE

• Identification: morphology and kinematics.• Physical conditions in shocked regions of PNe:

NGC 6543, NGC 7009, IC 4634.• Irradiated shocks: observational properties and

numerical simulations.

IDENTIFICATION

Small-scale structures which Small-scale structures which differdiffer from their from their surroundings in emission line spectra (low-surroundings in emission line spectra (low-excitation spectra) and velocities. excitation spectra) and velocities.

• Morphology Pair or string of knots, jet-like structures which

appear in opposite symmetrical pairs, or point-symmetrical features.

• Kinematics

The first high-velocity collimated outflow in a PN was found by Gieseking, Becker & Solf (1985) in NGC 2392, Vexp = 200 km s-1

Jets and “ansae”:

NGC 6543 (Miranda & Solf 1992): Vexp = 130 (250) km s-1

Hubble 4 (López, Steffen & Meaburn 1997): Vexp= 200 km s-1

MyCn 18 (O’Connor et al. 2000): V in excess of 500 km s-1

NGC 7009 (Fernández, Monteiro & Schwarz 2004) : proper motion measurements Vexp = 115 km s-1

Reviews: López (2000, 2002), Gonçalves (2004), Corradi (2006).

• FLIERs (Fast Low Ionization Emission Region) Balick et al. (1987, 1993, 1994) Morphology of jets or knots (axial symmetry). Sizes = few x 1016 cm. Doppler shifts ± 25 – 50 km s-1.

• BRETs (Bipolar, Rotating, Episodic jeT) (López et al. 1993) Point-symmetric pair or string of knots.

• LIS (Low Ionization Structures) (Corradi et al. 1996, Gonçalves et al. 2001).

Sub-class of jet-like structures (moderate to high expansion velocities).

↓ associated with collimated outflows

Studies of the Physical Conditions of shock-excited features.Balick et al. (1993, 1994), Hajian et al. (1997), Balick et al. (1998),Gonçalves et al. (2003), Perinotto et al. (2004).

• Spectral properties: high low ionization lines ([O I], [N II], [S II], [O II]).

• Kinematics: Doppler shifts ± 25 to 50 km s-1

• Ionization stratification: decreasing gradient of ionization with distance from the star (HST + WFPC2).

• Moderate temperatures and densities.

Figure from Balick et al. (1998)

Shocks or photoionization ?

NGC 6543

Credit: NASA, ESA,HEIC, and the Hubble Heritage Team (STScI/AURA).

IC 4634: Bow-shaped structures A,A’, B, B’

Guerrero et al. (in preparation)

Hα, [N II] and [O III] composite pictures of A, A’.

K 4-47

M 2-48

Figure from Gonçalves et al. (2004)

Figure from Gonçalves et al. (2004)

Figure from Vázquez et al. (2000)

Physical conditions in shock-excited PPNe and PNe

Name

Region (ref.)

Ne [SII](cm-3)

Te [N II]

Te [O III]

Hen 3-1475 NW1 (1) 2960 25200 --

SE1 (1) 1260 - 1880 16500 -26900

NW2 (2) 3200 15500 --

SE2 (2) 2800 18000 --

CRL 618 (3) 2.0 x 104 18000 --

E lobe (4) 3.2 x 104 18000 --

W lobe (4) 2.0 x 104 11000 --

M 1-92 NW lobe (4) 9000 < 16000 --

SE lobe (4) 5000 < 13000 --

M 2-56 (4) 800 < 20000 --

M 2-48 Core (5) 1260 10700 10850

s1 (5) 180 20100 --

B1 (5) < 100 -- --

K 4-47 Core (6) 1900 21000 19300

Knot 1 (6) 4600 19000 > 21000

Knot 2 (6) 2400 17000 16100

(1) Riera, Binette & Raga (2006) HST + STIS spectroscopy (2) Riera et al. (1995) Long-slit spectroscopy (3) Schmidt & Cohen (1981) Spectropolarimetry (4) Trammell, Dinerstein & Goodrich (1993) Spectropolarimetry (5) López-Martín et al. (2002) Long-slit spectroscopy (6) Gonçalves et al. (2004) Long-slit spectroscopy

STIS data of NGC 7662 (Perinotto et al. 2004): FLIERs are denser than the nebular gas (104 cm-3); Te [N II] from 9800 to 12000 k.

FLIERs: Physical conditions

Name

Region

Ne [SII](cm-3)

Te [N II]

Te [O III]

NGC 6543 (1) N Rim 4600 9300 8000

N Cap 5000 9000 7900

N Flier 2200 7400 8200

NGC 6543 (2) N Shell 7350 9250 8100

N Cap 9150 8450 7950

S Cap 5550 9000 7600

N Jet 2000 7600 9850

S Jet 1150 7000 9250

NGC 7009 (1) W Rim 4900 10000 9400

W Cap 4100 9600 9600

W Flier 1000 8100 11500

NGC 7009 (3) W Cap 5000 10400 10100

W Flier 1300 11700 10400

E Cap 4500 9400 9300

E Flier 2000 11000 9600

IC 4634 (4) BS A 2800 9600 11350

BS A’ 1500 11600 10700

Shell 10600 13150 9850

(1) Balick et al. (1994) (2) Gonçalves (2007) (3) Gonçalves et al. (2003) (4) Guerrero et al. (in preparation)

NGC 7009

IC 4634

NGC 6543

Δ M1-92, M2-56, OH238.1+4.2 Trammell. Dinerstein & Goodrich (1993), Sánchez Contreras et al. (2000)

□ Hen 3-1475 (STIS + HST, ground spectroscopy)

Riera et al. (1995, 2003)

* CRL 618 (STIS + HST) (Riera et al. In prep.)

□ BS M 2-48, K 4-47 (ground-spect.) López-Martín et al. (2002),

Gonçalves et al. (2004).

▲ Δ NGC 7009 (ground-spect.) Balick et al. (1994), Gonçalves et al.

(2003).

■ □ IC 4634 (ground-spect.) Guerrero et al. (in prep.)

● ○ NGC 6543 (ground-spect.) Balick et al. (1994)

Δ M1-92, M2-56, OH238.1+4.2□ Hen 3-1475

* CRL 618

□ BS M 2-48, K 4-47 ▲ Δ NGC 7009 (WFPC2)(reduced images provided by B. Balick). Balick et al. (1998)

■ □ IC 4634 (WFPC2)Guerrero et al. (in prep.)

● ○ NGC 6543 (WFPC2)(reduced images provided by B. Balick; Balick 2004). Lame, Harrington & Borkowski (1997)

Irradiated shocks: numerical simulations (Raga, Riera & Mellema in prep.)

• Description

2D, axisymmetric simulations of a high velocity bullet that moves away from the central star through the photoionized, nebular gas.

We include the radiation field from the central star that penetrates the recombination region behind the leading bow-shock in the direction from the post-shock to the pre-shock region.

Gasdynamic code (described in Mellema et al. (1997)) using a 3-level binary adaptative grid, that includes radiative, dielectronic and charge exchange recombinations, collisional ionization and photoionization for several species.

• Parameters

Clump: n = 103 cm-3 , T = 104 K, r = 1016 cm. V = 100 km s-1 . Fully (singly) ionized (i.e. H+/H = 1, He+/He = 1). Ambient gas: n = 102 cm-3 , T = 104 K. Fully (singly) ionized. Chemical abundances: mean PN abundances (Kingsburgh &

Barlow 1994) Stellar parameters: T* (BB) = 50000 K, L* = 5000 LΘ

Model Distance (cm)

M1 3 x 1018

M2 1018

M3 3 x 1017

• Results

M1 M2 M3

Density (cm-3) (top panels) and neutral fraction of H (bottom panels) at different integration times.

M2

Fraction of different ions of O for model M2 for an integration time of 200 years.

M1 M2 M3

• Diagnostic diagrams

● ○ Numerical simulations

CONCLUSIONS

• High spatial spectroscopy of shocked regions in PNe is needed: are FLIERs denser than the surrounding nebular gas?.

• Numerical simulations of “irradiated shocks” reproduce some of the properties observed in shock-excited regions in PNe, as the decreasing gradient of ionization with distance to the star.

We have to explore with larger values of the stellar temperature or/and the velocity of the clump.