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Title: THE BORN-AGAIN PLANETARY NEBULA A78: AN X-RAY TWIN OF A30

We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar wind and a point-like source at the position of the central star (CSPN). We present the spectral analysis of the CSPN, using for the first time an NLTE code for expanding atmospheres that takes line blanketing into account for the UV and optical spectra. The wind abundances are used for the X-ray spectral analysis of the CSPN and the diffuse emission. The X-ray emission from the CSPN in A78 can be modeled by a single C VI emission line, while the X-ray emission from its diffuse component is better described by an optically thin plasma emission model with a temperature of kT = 0.088 keV (T ≈ 1.0 × 10{sup 6} K). We estimate X-ray luminosities in the 0.2-2.0 keV energy band of L {sub X,} {sub CSPN} = (1.2 ± 0.3) × 10{sup 31} erg s{sup –1} and L {sub X,} {sub DIFF} = (9.2 ± 2.3) × 10{sup 30} erg s{sup –1} for the CSPNmore » and diffuse components, respectively.« less
Authors:
; ; ;  [1] ; ; ;  [2] ; ;  [3] ;  [4] ;  [5]
  1. Instituto de Astrofísica de Andalucía IAA-CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain)
  2. Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, D-14476 Potsdam (Germany)
  3. Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States)
  4. Leibniz-Institut Für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
  5. Instituto de Astronomía y Meteorología, Av. Vallarta No. 2602, Col. Arcos Vallarta, 44130 Guadalajara (Mexico)
Publication Date:
OSTI Identifier:
22364484
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COSMIC PHOTONS; COSMIC X-RAY SOURCES; KEV RANGE; LUMINOSITY; OPTICALLY THIN PLASMA; PLANETARY ATMOSPHERES; PLANETARY NEBULAE; SOFT X RADIATION; STARS; STELLAR WINDS