Departures from Axisymmetry in PNe and SN1987A

M. Bobrowsky

Axisymmetry is well known. (It forms in the last part of the superwind phase -- e.g., see poster by Speck & Dijkstra)

Classifications and correlations done by:Balick 1987, 2007 (APN4)Corradi & Schwarz 1995Manchado et al. 1996, 2000Sahai et al. 2007Schwarz, Corradi, & Stanghellini 1992Shaw et al. 2001 Stanghellini et al. 1999, 2000, 2002

• Classification of deviations from axisymmetry

• Soker & Hadar (2002) considered several types of departure from axisymmetry

• Limited mainly to departures in the equatorial plane

Cause of departure — external or internalExternal (e.g., interaction with the ISM)Observations: Jacoby 1981; Tweedy & Kwitter

1994, 1996; Xilouris et al. 1996; Kerber et al. 2000, 2001; Muthu, Anandarao & Pottasch 2000, Rauch et al. 2000; Martin, Xilouris & Soker 2002

Theory: Borkowski, Sarazin, & Soker 1990; Soker, Borkowski, & Sarazin 1991; Villaver, Manchado, & Garcia-Segura 2000;Villaver, Garcia-Segura, & Manchado 2003; Villaver, Garcia-Segura, & Manchado 2003; Dgani & Soker 1998; see Dgani 2000 for a review

Internal Departure (e.g., binary companion)Observations

Soker, Rappaport, & Harpaz 1998; Soker 1994, 1999

Theory:Sahai 2000; Miranda et al. 2001; Miranda, Guerrero,

& Torrelles 2001

About 50% of all PNe in Soker and Hadar’s sample have large-scale departure (compared to a 25-30% incidence of binaries).

In the present work, 58% were found to have a departure from axisymmetry.

Questions to Answer

• What can we learn from the departures from axisymmetry?

• Can departures be generalized to other objects?

Types of Departure

Types of Departure

• Displacement of the Central Star

IC 418

(Also see poster by Morisset & Georgiev)

MyCn 18

MyCn 18

Hen 3-1357 (The Stingray Nebula)

Central Star Displacement in the Stingray Nebula

R/R ~10%

Assume: age = 104 yr, mass of companion = 1 Msun, and mass of central star = 1 Msun before losing mass.

--> orbital period = 7.3 104 yr

Distance of central star from CM of system = 1100 AU

Orbital velocity = 0.5 km s-1

--> During nebular formation, star moved 1/8 of a circle in its orbit -- approximately 45˚.

SN 1987A

Types of Departure

• Displacement of the central star

Types of Departure

• Displacement of the central star

• Unequal size and shape of two sides

IRAS 16268-4556 = Hen 2-166

IRAS 20119+2924 = Hen 2-459

Types of Departure

• Displacement of the central star

• Unequal size and shape of two sides

Types of Departure

• Displacement of the central star

• Unequal size and shape of two sides

• Bent planetary nebulae

IRAS 16409-1851 = Hen 2-180

IRAS 16409-1851 = Hen 2-180

NGC 6886

Types of Departure

• Displacement of the central star

• Unequal size and shape of two sides

• Bent planetary nebulae

Types of Departure

• Displacement of the central star

• Unequal size and shape of two sides

• Bent planetary nebulae

• Different lobe structures

IRAS 21282+5050 = J900

PK 130-11˚1

Why different structures?

• Instabilities in outer lobes when a fast wind interacts with jets? (See poster by Akashi, Soker, & Blondin.)

• Fragmentation of explosively launched clumps? (See poster by Dennis, Cunningham, Frank, Balick, & Mitran.)

• Other possibilities?

Podsiadlowski & Cumming 1994

SN 1987A Model

Morris & Podsiadlowski 2007, Science, 315, 1103

Podsiadlowski 2007, APN4

How to explain the additional 2 km sec-1 velocity?

Possibilities include:

• a non-radial pulsational mode excited during the early spiral-in phase

• orbital motion caused by a more distant low-mass third star in the system

Conclusions

• Departures from axisymmetry are significant and measurable.

• Orbital motion can give expelled mass additional velocity in the direction of orbital motion.

• Prospects for the Future: Generalize to other types of objects? Possibly, but use caution!