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 Irradiated shocks: observational properties and numerical simulations.

IDENTIFICATION Small-scale structures which differ from their surroundings in emission line spectra (low- 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 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) NGC 6543 Credit: NASA, ESA,HEIC, and the Hubble Heritage Team (STScI/AU RA).

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 Figure from Corradi et al. (2000) IC 4634 Guerrero et al. (in preparation)

K 4-47 M 2-48 Figure from Gonçalves et al. (2004) Figure from Vázquez et al. (2000)

PPNe Outflows : what can tell us? F555w blue F502N green F656N yellow-orange F673N orange-red F814W red Figure from Trammell & Goodrich (2002) A. Riera (UPC), P. García-Lario (ESA) & ESA

STIS data of NGC 7662 (Perinotto et al. 2004): FLIERs are denser than the nebular gas (10 4 cm -3 ); Te [N II] from 9800 to k.

NGC 7009 IC 4634 NGC 6543

Δ M1-92, M2-56, OH Trammell. Dinerstein & Goodrich (1993), Sánchez Contreras et al. (2000) □ Hen (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, OH □ Hen * 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 = 10 3 cm -3, T = 10 4 K, r = cm. V = 100 km s -1. Fully (singly) ionized (i.e. H + /H = 1, He + /He = 1).  Ambient gas: n = 10 2 cm -3, T = 10 4 K. Fully (singly) ionized.  Chemical abundances: mean PN abundances (Kingsburgh & Barlow 1994)  Stellar parameters: T * (BB) = K, L * = 5000 L Θ ModelDistance (cm) M13 x M M33 x 10 17

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.

M1M2M3

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.