Physical Structure of Planetary Nebulae. I. The Owl Nebula

Abstract

The Owl Nebula is a triple-shell planetary nebula with the outermost shell being a faint bow-shaped halo. We have obtained deep narrow-band images and high-dispersion echelle spectra in the H-alpha, [O III], and [N II] emission lines to determine the physical structure of each shell in the nebula. These spatio-kinematic data allow us to rule out hydrodynamic models that can reproduce only the nebular morphology. Our analysis shows that the inner shell of the main nebula is slightly elongated with a bipolar cavity along its major axis, the outer nebula is a filled envelope co-expanding with the inner shell at 40 km/s, and the halo has been braked by the interstellar medium as the Owl Nebula moves through it. To explain the morphology and kinematics of the Owl Nebula, we suggest the following scenario for its formation and evolution. The early mass loss at the TP-AGB phase forms the halo, and the superwind at the end of the AGB phase forms the main nebula. The subsequent fast stellar wind compressed the superwind to form the inner shell and excavated an elongated cavity at the center, but has ceased in the past. At the current old age, the inner shell is backfilling the central cavity.

arXiv comment10 pages, 6 figures, 1 table, to appear in the Astronomical Journal

References in corpus (5)

• The Dynamical Evolution of the Circumstellar Gas around Low- and Intermediate-Mass stars.II. The Planetary Nebula formation
• Sulfur, Chlorine, & Argon Abundances in Planetary Nebulae. I: Observations and Abundances in a Northern Sample
• From the Owl to the Eskimo: the Radiation-Gasdynamics of Planetary Nebulae IV
• The triple-shell structure and collimated outflows of the planetary nebula NGC 6891
• The ISM Interactions of a Runaway LBV Nebula in the LMC

Cited by in corpus (20)

• The jet feedback mechanism (jfm) in stars, galaxies and clusters
• (Sub)stellar companions shape the winds of evolved stars
• Evolution and Mass Loss of Cool Ageing Stars: a Daedalean Story
• The evolution of planetary nebulae. VIII. True expansion rates and visibility times
• Why a Single-Star Model Cannot Explain the Bipolar Nebula of Eta Carinae
• Spatially resolved spectroscopy of planetary nebulae and their halos I. Five galactic disk objects
• ATOMIUM: ALMA tracing the origins of molecules in dust forming oxygen rich M-type stars: Motivation, sample, calibration, and initial results
• SPH modelling of companion-perturbed AGB outflows including a new morphology classification scheme
• Bubbles in Planetary Nebulae and Clusters of Galaxies: Jet Properties
• Comparing Eta Carinae with the Red Rectangle
• The Binarity of Eta Carinae and its Similarity to Related Astrophysical Objects
• Bubbles in Planetary Nebulae and Clusters of Galaxies: Jet Bending
• Physical Structure of Planetary Nebulae. II. NGC 7662
• Physical Structure of Planetary Nebulae. III. The Large and Evolved NGC 1360
• Pairs of Bubbles in Planetary Nebulae and Clusters of Galaxies
• Counterparts of Far Eastern Guest Stars: Novae, supernovae, or something else?
• The Owl and other strigiform nebulae: multipolar cavities within a filled shell
• The nebula around the binary post-AGB star 89 Herculis
• Bubbles in Planetary Nebulae and Clusters of Galaxies: Instabilities at Bubble Fronts
• H${}_2$ molecular gas in the old planetary nebula NGC 3587