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)‏

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 ?

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?

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

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

NGC 6537 HST data

NGC 6537: HST vs SCUBA Submm size: ~ 20 x 20 arcsec² Strong Bipolar PN Hot central star (1.5-2.5 x 10^ 5 K)‏ O-rich Submm size: ~ 20 x 20 arcsec²

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) °

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

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

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 %

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

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

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)°

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

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

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

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% - 3.2 % - 8.8%

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

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.

Relation between B and the physical properties of the PNe/PPN ? 2- Evolutionary stage: Nebulae extent : CRL 2688, NGC 7027, NGC 6537 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.

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)

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 376-378 Greaves J.S., 2002 , A&A, Vol 392, p L1-L4