SIMBAD references

2019ApJ...884..134G - Astrophys. J., 884, 134-134 (2019/October-3)

Variable hard X-ray emission from the central star of the Eskimo nebula.


Abstract (from CDS):

The central star of NGC 2392 shows the hardest X-ray emission among central stars of planetary nebulae (CSPNe). The recent discovery of a spectroscopic companion with an orbital period of 1.9 days could provide an explanation for its hard X-ray emission, as well as for the collimation of its fast outflow. Here, we analyze the available Chandra and XMM-Newton X-ray observations to determine accurately the spectral and temporal variation properties of the CSPN of NGC 2392. The X-ray emission can be described by an absorbed thermal plasma model with temperature 26–5+8 MK and X-ray luminosity (8.7 ± 1.0) x 1030 erg s–1. No long-term variability is detected in the X-ray emission level, but the Chandra light curve is suggestive of short-term variations with a period ∼0.26 days. The possible origins of this X-ray emission are discussed. X-ray emission from the coronal activity of a companion or shocks in the stellar wind can be ruled out. Accretion of material from an unseen main-sequence companion onto the CSPN or from the CSPN wind onto a white dwarf companion are the most plausible origins for its hard X-ray emission, although the mismatch between the rotational period of the CSPN and the modulation timescale of the X-ray emission seems to preclude the former possibility.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): Planetary nebulae - Planetary nebulae nuclei - X-ray stars - Stellar winds

Simbad objects: 12

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