Limits to the magnetic field in the planetary nebula NGC 246 from faraday rotation

• We present radio continuum observations of the linearly polarized extragalactic source J0047-1150, whose line of sight traverses the galactic planetary nebula NGC 246. We determine the position angle of the electric vector at seven frequencies between 1.3 and 1.8 GHz, finding no evidence of Faraday rotation and setting a 4-sigma upper limit to the rotation measure of 9.6 rad m(-2), which implies an upper limit to the average line-of-sight component of the magnetic field in NGC 246 of 1.3 mu G. However, we show that the rotation measure across a source with a dipolar magnetic field morphology practically cancels out. Therefore, if the magnetic field has this morphology, the local values of the magnetic field in NGC 246 could be much larger and will not be evident in a Faraday rotation experiment.

Ämnesord

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Nyckelord

polarization

plasmas

planetary nebulae: individual (NGC 246)

ISM: magnetic fields

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)