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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 1995 - PowerPoint PPT Presentation
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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!