2009/04/30 by Lizette Guzman, Lizette Guzmán, Laurent Loinard +3 · 2 citations
Physics and Astronomy · #Angular diameter #Angular velocity #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Ionization #Nebula #Parallax #Planetary nebula #Stellar, planetary, and galactic studies #astro-ph.GA #astro-ph.SR
paper · pdf · doi:10.1088/0004-6256/138/1/46
Accepted in the Astronomical Journal
arxiv created 2009/04/30 · openalex publication_date 2009/05/21 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In this paper, we present radio continuum observations of the planetary nebula IC 418 obtained at two epochs separated by more than 20 years. These data allow us to show that the angular expansion rate of the ionization front in IC 418 is 5.8 ± 1.5 mas yr −1 . If the expansion velocity of the ionization front is equal to the expansion velocity of the gas along the line of sight as measured by optical spectroscopy, then the distance to IC 418 must be 1.1 ± 0.3 kpc. Recent theoretical predictions appropriate for the case of IC 418, however, suggest that the ionization front may be expanding about 20% faster than the material. Under this assumption, the distance to IC 418 would increase to 1.3 ± 0.4 kpc.