X-ray observations of central stars of planetary nebulae and their winds

Guerrero, M. A.

doi:10.1017/s1743921312010964

Cited by 1 publication

(7 citation statements)

References 39 publications

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“…The orbital parameters of the newly discovered binary (Section 3) provide some additional insights into the mechanisms behind the X-ray emission. The X-ray spectrum consists of two apparent components: a mostly soft component peaking just after 1 keV and a hard X-ray tail of up to 5 keV (Guerrero 2012). Such a configuration most closely resembles that seen in the X-ray spectra of symbiotic stars (Muerset, Wolff, & Jordan 1997;Luna et al 2013).…”

Section: The X-ray Spectrum Of the Binary Nucleusmentioning

confidence: 56%

“…Previous spectral fitting of the X-ray spectrum of the central star of NGC 2392 involved fitting optically thin thermal plasmas (Guerrero 2012;Montez et al 2015). The orbital parameters of the newly discovered binary (Section 3) provide some additional insights into the mechanisms behind the X-ray emission.…”

Section: The X-ray Spectrum Of the Binary Nucleusmentioning

confidence: 99%

“…Although binary interactions offer the leading explanation for many phenomena (De Marco 2009;Jones & Boffin 2017), there are some phenomena that remain particularly enigmatic. The Chandra detection of relatively hard X-ray emission with peak energies > 0.5 keV in some central stars is one such phenomenon (Guerrero et al 2001, Guerrero, Chu, & Gruendl 2011Guerrero 2012Guerrero , 2015Kastner et al 2012;Freeman et al 2014;Montez et al 2015;Montez & Kastner 2013;Montez 2017). A wide range of explanations have been proposed (see Guerrero 2012 andMontez et al 2015 for comprehensive discussions) and include processes that can operate from central stars on their own (shocks in the stellar wind, emission from the atmosphere, and accretion of nebular or debris disk material) or in a binary system (colliding winds, accretion onto a companion, and coronal activity from late-type companions).…”

Section: Introductionmentioning

confidence: 99%

“…The Chandra detection of relatively hard X-ray emission with peak energies > 0.5 keV in some central stars is one such phenomenon (Guerrero et al 2001, Guerrero, Chu, & Gruendl 2011Guerrero 2012Guerrero , 2015Kastner et al 2012;Freeman et al 2014;Montez et al 2015;Montez & Kastner 2013;Montez 2017). A wide range of explanations have been proposed (see Guerrero 2012 andMontez et al 2015 for comprehensive discussions) and include processes that can operate from central stars on their own (shocks in the stellar wind, emission from the atmosphere, and accretion of nebular or debris disk material) or in a binary system (colliding winds, accretion onto a companion, and coronal activity from late-type companions). Some detections may be explained by coronal activity only when the presence of late-type stellar companions was already independently established (Montez et al 2010(Montez et al , 2015.…”

Section: Introductionmentioning

confidence: 99%

“…The hardest X-ray emission of any central star belongs to NGC 2392 a (PN G197.8+17.3, Figure 1) which exhibits a spectrum peaking above 1 keV and a hard energy tail up to 5 keV (Guerrero 2012;Montez et al 2015). Guerrero (2012) favoured accretion onto a compact companion to explain the X-ray spectrum. Despite considerable indirect evidence supporting such a companion in the literature, its existence has yet to be proven.…”

Section: Introductionmentioning

confidence: 99%

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The post-common-envelope X-ray binary nucleus of the planetary nebula NGC 2392

Miszalski

Manick²,

Winckel³

et al. 2019

Publ. Astron. Soc. Aust.

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The Chandra X-ray Observatory has detected relatively hard X-ray emission from the central stars of several planetary nebulae (PNe). A subset have no known late-type companions, making it very difficult to isolate which of several competing mechanisms may be producing the X-ray emission. The central star of NGC 2392 is one of the most vexing members, with substantial indirect evidence for a hot white dwarf (WD) companion. Here we report on the results of a radial velocity (RV) monitoring campaign of its central star with the HERMES échelle spectrograph of the Flemish 1.2 m Mercator telescope. We discover a single-lined spectroscopic binary with an orbital period of 1.902208 ± 0.000013 d and a RV semi-amplitude of 9.96 ± 0.13 km s −1 . The high degree of nebula ionisation requires a WD companion (M 0.6M ), which the mass-function supports at orbital inclinations 7 deg, in agreement with the nebula orientation of 9 deg. The hard component of the X-ray spectrum may be explained by the companion accreting mass from the wind of the Roche lobe filling primary, while the softer component may be due to colliding winds. A companion with a stronger wind than the primary could produce the latter and would be consistent with models of the observed diffuse X-ray emission detected in the nebula. The diffuse X-rays may also be powered by the jets of up to 180 km s −1 and active accretion would imply that they could be the first active jets of a post-common-envelope PN, potentially making NGC 2392 an invaluable laboratory to study jet formation physics. The 1.9 d orbital period rules out a double-degenerate merger leading to a Type Ia supernova and the weak wind of the primary likely also precludes a single-degenerate scenario. We suggest that a hard X-ray spectrum, in the absence of a late-type companion, could be a powerful tool to identify accreting WD companions.

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Section: The X-ray Spectrum Of the Binary Nucleusmentioning

confidence: 56%

Section: The X-ray Spectrum Of the Binary Nucleusmentioning

confidence: 99%