departures from axisymmetry in pne and sn1987a
DESCRIPTION
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 PresentationTRANSCRIPT
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!