2008/06/09 by R. R. Ransom, Ryan Ransom, B. Uyanker +5
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Dark nebula #Emission nebula #Interstellar medium #Nebula #Planetary nebula #Protoplanetary nebula #Stars #Stellar, planetary, and galactic studies #Ultraviolet astronomy #astro-ph
paper · pdf · doi:10.1086/590656
25 pages, 4 figures. Accepted for publication in the Astrophysical Journal
arxiv created 2008/06/09 · openalex publication_date 2008/09/04 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present 1420 MHz polarization images of a 2.5° × 2.5° region around the planetary nebula (PN) Sh 2-216. The images are taken from the Canadian Galactic Plane Survey (CGPS). An arc of low polarized intensity (size 0.2° × 0.7°) appears prominently in the northeast portion of the visible disk of Sh 2-216, coincident with the optically identified interaction region between the PN and the interstellar medium (ISM). The arc contains structural variations down to the ~1' resolution limit in both polarized intensity and polarization angle. Several polarization-angle "knots" appear along the arc. By comparison of the polarization angles at the centers of the knots and the mean polarization angle outside Sh 2-216, we estimate the rotation measure (RM) through the knots to be –43 ± 10 rad m −2 . Using this estimate for the RM and an estimate of the electron density in the shell of Sh 2-216, we derive a line-of-sight magnetic field in the interaction region of 5.0 ± 2.0 μ G . We believe it more likely the observed magnetic field is interstellar than stellar, although we cannot completely dismiss the latter possibility. We interpret our observations via a simple model which describes the ISM magnetic field around Sh 2-216, and comment on the potential use of old PNe as probes of the magnetized ISM.