1. Magnetic fields in Planetary and Proto Planetary
Nebulae
Laurence Sabin (IAC ,SPAIN / Manchester,UK)‏
A.A. Zijlstra (Manchester,UK) and J.S. Greaves (St Andrews,UK)‏

2. 3 Shaping Models
✸Wind-Wind interaction. BUT need of initial axisymmetrical structure.
✸Binarity. BUT lack of observational evidence.
✸Magnetic fields (B): detectable, measurable (spectropolarimetry) , local (maser:H2O). AND Can a single star supply the energy necessary to create a strong Bfield ?

3. Magnetic Model I) Detection of global magnetic fields.
II) Characteristics of the field in 4 bipolar objects
III) Relation with the physical properties of the targets.
IV) What is the role of B in the shaping of Post- AGBs and PNe?

4. Observations SCUBA at the JCMT
Bands: 450 µm and 850 µm ( jiggle-map mode)‏
Dust distribution and polarization.
Dust grains have their long axis  B
No strength value

5. The Sample
Small : 4 objects
Unique : NO other known data
“Death” of SCUBA

6. NGC 6537
HST data

7. NGC 6537: HST vs SCUBA Submm size: ~ 20 x 20 arcsec² Strong Bipolar PN
Hot central star ( x 10^ 5 K)‏
O-rich
Submm size: ~ 20 x 20 arcsec²

8. NGC 6537 at 850µm: B  Well defined toroidal magnetic field.
Magnetic Field distribution:
- Does not cover all the nebula
- Organized (1 main direction)‏
- Consistent (small variation of polarization degree & no change in geometry)‏
Bfield in the SE-NW direction = equatorial plane
 Well defined toroidal magnetic field.
mp:(11.2 ± 2.2) %, ma: (26.5 ± 5.7) °

9. NGC 7027
Credit: W. B. Latter et al., HST, NICMOS

10. NGC 7027: HST vs SCUBA Young Bipolar PN C-rich
Submm size: ~ 40 x 36 arcsec²

11. NGC 7027 at 450 µm: B Toroidal magnetic field. B distribution :
-All over the nebula
-Mainly along the equatorial plane -Field disturbed in the SW.
-Lower degree of polarization in the center: no coherence of B (ionization)‏
Toroidal magnetic field.
NE: mp=8.9±0.9 % SW: mp=7.6±1.3 %

12. NGC 6302
2,2m ESO.Courtesy: R. Corradi & A. Zijlstra

13. NGC 6302: 2.2mESO vs SCUBA Bipolar PN O-Rich Submm size:
~ 1.7 x 1 arcmin²

14. NGC 6302 at 450 µm B distribution: -Does not cover all the nebula
-Few polarization vectors
-B consistent & organized
-No alignment with the equatorial plane
mp: (11.4 ±1.6) % ma: (32.7± 4.6)°

15. NGC 6302 at 450 µm
B localized and aligned at the radio core position : Not Toroidal

16. CRL 2688
HST data. Credit: R. Sahai, J. Trauger

17. CRL 2688: HST vs SCUBA PPN C-rich Binary?
Submm size: ~ 60 x 45 arcsec²
Composite: Visible+ IR
HST data. Credit: R. Sahai, J. Trauger, R. Thompson

18. CRL 2688 at 850 µm B distribution: - Covers the entire nebula
-Field locally broken
-Decrease of
polarization degree (torus interaction)‏
-Two main directions
POLOIDAL & TOROIDAL magnetic fields
mp: 1.4% % - 8.8%

19. CRL 2688 at 450 µm
B distribution: Same conclusion as for the 850µm data.
(higher resolution)‏
- Covers most of nebula
- Two main directions
- Undersampling

20. Relation between B and the physical properties of the PNe/PPN ?
1-Chemistry :
C-rich (CRL 2688 & NGC 7027) : Disorganized B located all over the nebula
O-rich (NGC 6537 & NGC 6302): Organized B near the central region
 Dependence on the nature , geometry and size of the dust grains. Need of models.

21. Relation between B and the physical properties of the PNe/PPN ?
2- Evolutionary stage:
Nebulae extent : CRL 2688, NGC 7027, NGC and NGC 6302.
Younger Nebulae: Disorganized B
Older Nebulae: Organized B
 Long lived B.
 Toroidal magnetic fields are becoming dominant while the nebulae evolve. Need of observations.

22. Scenario for PNe/PPN shaping with magnetic fields
AGB star = dipole-like
Action of companion for toroidal B ****
Poloidal field carried by the outflows
Toroidal field getting more organized and magnetic field becomes more important/dominant. 
AGB
PPN PN
**** Re-seeding process (J. Nordhaus, APN4)

23. Sabin L. , Zijlstra A.A, and Greaves J.S, 2007, MNRAS, Vol 376-378
More details:
Sabin L. , Zijlstra A.A, and Greaves J.S, 2007, MNRAS, Vol
Greaves J.S., 2002 , A&A, Vol 392, p L1-L4