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Magnetic fields in Planetary and Proto Planetary

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.

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Magnetic fields in Planetary and Proto Planetary

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

  8. NGC 6537 at 850µm: B 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 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 Bdistribution: • -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 • Bdistribution: • - 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%

  19. CRL 2688 at 450 µm • Bdistribution: 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 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.

  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. 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

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