Rummaging inside the Eskimo's parka: Variable asymmetric PN fast wind and a binary nucleus?

Abstract

We report on high-resolution optical time-series spectroscopy of the central star of the `Eskimo' planetary nebula NGC~2392. Datasets were secured with the ESO 2.3m in 2006 March and CFHT 3.6m in 2010 March to diagnose the fast wind and photospheric properties of the central star. The HeI and HeII recombination lines reveal evidence for clumping and temporal structures in the fast wind that are erratically variable on timescales down to ~ 30 min. (i.e. comparable to the characteristic wind flow time). We highlight changes in the overall morphology of the wind lines that cannot plausibly be explained by line-synthesis model predictions with a spherically homogeneous wind. Additionally we present evidence that the UV line profile morphologies support the notion of a high-speed, high-ionization polar wind in NGC~2392. Analyses of deep-seated, near-photospheric absorption lines reveals evidence for low-amplitude radial velocity shifts. Fourier analysis points tentatively to a ~ 0.12-d modulation in the radial velocities, independently evident in the ESO and CFHT data. We conclude that the overall spectroscopic properties support the notion of a (high inclination) binary nucleus in NGC~2392 and an asymmetric fast wind.

arXiv commentMNRAS in press; 9 pages; 9 figures

References in corpus (7)

• The Chandra X-ray Survey of Planetary Nebulae (ChanPlaNS): Probing Binarity, Magnetic Fields, and Wind Collisions
• Indications of a Large Fraction of Spectroscopic Binaries Among Nuclei of Planetary Nebulae
• Analysis of Far-UV Data of Central Stars of Planetary Nebulae: Occurrence and Variability of Stellar Winds
• A Detailed Morpho-Kinematic Model of the Eskimo, NGC 2392. A Unifying View with the Cat's Eye and Saturn Planetary Nebulae
• PN fast winds: Temporal structure and stellar rotation
• Looking deep into the Cat's Eye: Structure and rotation in the fast wind of the PN central star of NGC6543
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• The Chandra Planetary Nebulae Survey (ChanPlaNS): III. X-ray Emission from the Central Stars of Planetary Nebulae
• Tomography of the unique on-going jet in the planetary nebula NGC 2392
• The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392
• Is the central binary system of the planetary nebula Henize 2-428 a Type Ia supernova progenitor?
• Variable Hard X-ray Emission From the Central Star of the Eskimo Nebula