Discovery of a halo around the Helix Nebula NGC 7293 in the WISE all-sky survey

Abstract

We report the discovery of an extended halo (40' in diameter) around the planetary nebula NGC7293 (the Helix Nebula) observed in 12micron band from the Wide-field Infrared Survey Explorer all-sky survey. The mid-infrared halo has an axisymmetric structure with a sharp boundary to the northeast and a more diffuse boundary to the southwest, suggesting an interaction between the stellar wind and the interstellar medium (ISM). The symmetry axis of the halo is well aligned with that of a northeast arc, suggesting that the two structures are physically associated. We have attempted to fit the observed geometry with a model of a moving steady-state stellar wind interacting with the ISM. Possible combinations of the ISM density and the stellar velocity are derived from these fittings. The discrepancies between the model and the observations suggest that the stellar mass loss has a more complicated history, including possible time and angle dependences.

15 pages, 2 figures, accepted by ApJ

References in corpus (10)

• A Debris Disk around the Central Star of the Helix Nebula?
• The interaction of planetary nebulae and their AGB progenitors with the interstellar medium
• Computing the dust distribution in the bowshock of a fast moving, evolved star
• Infrared Observations of The Helix Planetary Nebula
• Vortices in the wakes of AGB stars
• Double bow shocks around young, runaway red supergiants: application to Betelgeuse
• The Halos of Planetary Nebulae in the Mid-Infrared: Evidence for Interaction with the Interstellar Medium
• Cometary Astropause of Mira Revealed in the Far-Infrared
• Optical line profiles of the Helix planetary nebula (NGC 7293) to large radii
• The Halo and Rings of the Planetary Nebula NGC 40 in the Mid-Infrared

Cited by in corpus (11)

• A catalogue of integrated H-alpha fluxes for 1,258 Galactic planetary nebulae
• The Herschel Planetary Nebula Survey (HerPlaNS) I. Data Overview and Analysis Demonstration with NGC 6781
• Extended Structures of Planetary Nebulae Detected in H${}_2$ Emission
• The ionization structure of multiple shell planetary nebulae: I. NGC 2438
• Planck intermediate results. XVIII The millimetre and sub-millimetre emission from planetary nebulae
• Herschel imaging of the dust in the Helix Nebula (NGC 7293)
• Planetary Nebulae Research: Past, Present, and Future
• The bow-shock and high-speed jet in the faint, 40 arcmin diameter, outer halo of the evolved Helix planetary nebula (NGC 7293)
• Discovery of Extended Structures around Two Evolved Planetary Nebulae M 2-55 and Abell 2
• FAST search for circumstellar atomic hydrogen. II. Is BD+303639 an interacting planetary nebula?
• Current Unsolved Problems in Planetary Nebulae Research