Signatures of Magnetic Field Structure in Planetary Nebulae P. J. Huggins, New York University PNe as MHD systems PNe as MHD systems

Can we see MHD in PNe ? ample evidence for mag fields in PNe: jet origin – binary disks/single stars fields in AGB envelopes and proto/young-PNe surface fields CS PNe (Jordan et al. 05) can we identify direct effects of MHD in PN images is the complex structure in PNe caused by MFs ? can structure be used to probe MF ? we divide the question into 3 parts: what to look for ? is there morphological evidence in PN images ? are the fields strong enough ?

Morphology of magnetic fields 1.4 GHz Lang et al Angstrom TRACE strong field cases: longitudinal coherence

Molecular Clouds gravity thermal pressure turbulence magnetic field right: filaments in Orion 850  emission polarized Johnstone & Bally 99 left: elephant trunks in Rosette Nebula H  Carlqvist et al. 03

Looking for MHD in PNe morphological signature: connectedness – filaments PNe are different from the molecular cloud case: turbulence weak, radial velocity helps preserve geometry source of magnetic fields: central star 10” at 500 pc ~ cm, B~r n, n= 1,2,3 – uncertain strategy search for connected structures examine what fields are needed to provide coherence we present 3 examples

NGC ” x 61”

tangential, multi-stranded, looped width ~ cm, l/w >60 proposal: magnetic filaments n ~ 10 5 cm -3, P ~ dyne cm -2 NGC 3132 [O III] [N II] 12” x 19”

tangential, l/w>40, like spaghetti proposal: magnetic filaments n~ cm -3, P~10 -7 dyne cm -2 IC 418 H  un-sharp mask 18” x 18”

tangential, l/w>40, like spaghetti proposal: magnetic filaments n~ cm -3, P~10 -7 dyne cm -2 IC 418 [N II], H  un-sharp mask 18” x 18”

NGC 6537 H , [N II] field 9” x 8” filaments part of torus n~10 4 cm -3, P~ dynes

If filaments are magnetic are the fields strong enough ? rough field estimates:  = 8  P/B 2 ~ 1, pressure  = B 2 /4  v 2 ~ 1, n v exp compare with AGB fields our estimates are upper limits  1/10 still robust likely compression AGB – PN transition “magnetic filament” concept consistent with AGB fields ~ mG at cm

Summary & Conclusions Magnetic fields produce connected structures – filaments PNe described here exhibit extreme filaments large length/width ratios & tangential, curved geometry field estimates consistent with fields in AGB envelopes Proposal: filaments are signatures of magnetic field difficult to produce in any other way Conclude: PN fields are localized and stringy Not convinced? Challenge: form similar filaments without fields