The Helix Nebula is a low-density, stratified object with near-solar oxygen abundance (8.7), a ~1 dex sulfur deficit, and moderate helium/nitrogen enrichment placing it near the Type I boundary, with abundance variations attributed to ionization structure rather than chemical inhomogeneity.
The bow-shock and high-speed jet in the faint, 40 arcmin diameter, outer halo of the evolved Helix planetary nebula (NGC 7293)
2 Pith papers cite this work. Polarity classification is still indexing.
2
Pith papers citing it
abstract
In previous, very deep, optical images of NGC 7293 both a feature that has the morphology of a bow-shock and one with that of a jet were discovered in the faint 40 arcmin diameter halo of the nebula. Spatially resolved longslit profiles of the Halpha and [N II] 6548, 6584 A nebular emission lines from both features have now been obtained. The bow-shaped feature has been found to have Halpha radial velocities close to the systemic heliocentric radial velocity, -27 km/s, of NGC 7293 and is faint in the [N II] 6548, 6584 A emission lines. Furthermore, the full width of these profiles matches the relative motion of NGC 7293 with its ambient interstellar medium consequently it is deduced that the feature is a real bow-shock caused by the motion of NGC 7293 as it ploughs through this medium. The proper motion of the central star also points towards this halo feature which substantiates this interpretation of its origin. Similarly [N II] 6584 A line profiles reveal that the jet-like filament is indeed a collimated outflow, as suggested by its morphology, at around 300 km/s with turbulent widths of around 50 km/s. It's low Halpha/[N II] 6548, 6584 A brightness ratio suggests collisional ionization as expected in a high-speed jet.
years
2026 2verdicts
UNVERDICTED 2representative citing papers
Depositing stellar luminosity in an inner shell and cooling low-density outer cells produces a stable pulsating 3D red supergiant model for common envelope simulations without relaxation.
citing papers explorer
-
SDSS-V LVM: Revealing the Physical and Chemical Structure of the Helix Nebula
The Helix Nebula is a low-density, stratified object with near-solar oxygen abundance (8.7), a ~1 dex sulfur deficit, and moderate helium/nitrogen enrichment placing it near the Type I boundary, with abundance variations attributed to ionization structure rather than chemical inhomogeneity.
-
Building three-dimensional giant stellar models for common envelope simulations
Depositing stellar luminosity in an inner shell and cooling low-density outer cells produces a stable pulsating 3D red supergiant model for common envelope simulations without relaxation.