Structure and clumping in the fast wind of NGC 6543

Prinja, R. K.; Hodges, Steve; Massa, Derck; Fullerton, A. W.; Burnley, A. W.

doi:10.1111/j.1365-2966.2007.12360.x

Cited by 17 publications

(32 citation statements)

References 44 publications

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“…Ions with higher ionization potential tend to have P Cyg lines with a more extended blue wing. In addition, Prinja et al (2007) showed that the wind variability is present in the absorbtion component of the P v k1118/k1128 doublet but that O vi k1032/k1038 is more stable. The formation of the strong P Cyg lines is obviously complicated, and there is no easy explanation for their behavior.…”

Section: Stellar Parametersmentioning

confidence: 99%

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Non–Local Thermodynamic Equilibrium Model of NGC 6543’s Central Star and Its Relation to the Surrounding Planetary Nebula

Георгиев

Peimbert

Hillier

et al. 2008

ApJ

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We analyze the chemical composition of the central star of the planetary nebula NGC 6543 based on a detailed NLTE model of its stellar wind. The logarithmic abundances by number are H ¼ 12:00, He ¼ 11:00, C ¼ 9:03, N ¼ 8:36, O ¼ 9:02, Si ¼ 8:19, P ¼ 5:53, S ¼ 7:57, and Fe ¼ 7:24. Compared with the solar abundances, most of the elements have solar composition with respect to hydrogen, except C, which is overabundant by 0.28 dex, and Fe, which is depleted by $0.2 dex. Contrary to most previous work, we find that the star is not H-poor and has a normal He composition. These abundances are compared with those found in the diffuse X-ray plasma and the nebular gas. Compared to the plasma emitting in diffuse X-rays, the stellar wind is much less depleted in iron. Since the iron depletions in the nebular gas and X-ray plasma are similar, we conclude that the plasma emitting diffuse X-rays is derived from the nebular gas rather than the stellar wind. Excellent agreement is obtained between the abundances in the stellar wind and the nebular recombination line abundances for He, C, and O relative to H. On the other hand, the derived stellar N abundance is smaller than the nebular N abundance derived from recombination lines and agrees with the abundance found from collisionally excited lines. The mean temperature variation determined by five different methods indicates that the difference in the nebular abundances between the recombination lines and collisionally excited lines can be explained as due to the temperature variations in a chemically homogeneous medium. Subject headingg s: planetary nebulae: individual ( NGC 6543)

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Section: Stellar Parametersmentioning

confidence: 99%

“…A detailed analysis of the spectral variability was published by Prinja et al (2007). They found that ''Mostly the flux changes are at $10%Y20% of the continuum level and occur over localized blueward velocity regions, as opposed to the flux increasing or decreasing simultaneously over the entire absorption trough.''…”

Section: Modelmentioning

confidence: 99%

Non–Local Thermodynamic Equilibrium Model of NGC 6543’s Central Star and Its Relation to the Surrounding Planetary Nebula

Георгиев

Peimbert

Hillier

et al. 2008

ApJ

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“…The red component of the doublet is usually blended with the Si iv λ1128.3 line, and thus we have focused on the blue component. The P Cygni profiles of unsaturated P v λ1118, 1128 lines have been singled out as a sensitive diagnostic of variable conditions in the wind of CSPNe (Prinja et al 2007). …”

Section: Atlas Of Fuse P-cygni Profiles Of Cspnementioning

confidence: 99%

“…When necessary, we adopted the Notes. (a) The FUSE spectra of Hen 2-138 and NGC 6543 have been thoroughly investigated by Prinja et al (2007Prinja et al ( , 2010 and will not be discussed in the following sections.…”

Section: Near-uv Datamentioning

confidence: 99%

“…The limited spectral resolution and sensitivity of IUE and the lack of complete time-series data prevented the search for patterns in the variability of the winds of these CSPNe. More recently, detailed studies of the time variability of the stellar winds of the CSPNe of IC 418, IC 2149, IC 4593, NGC 6543, NGC 6826 and Hen 2-138 have been obtained by Prinja et al (2007Prinja et al ( , 2010Prinja et al ( , 2012b using Far Ultraviolet Spectroscopic Explorer (FUSE) observations. These studies indicate that the stellar wind of these CSPNe are variable and, in the case of NGC 6543, this variability can be linked to the rotation of the star and so it has been used to measure its rotational velocity (Prinja et al 2012a).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of far-UV data of central stars of planetary nebulae: Occurrence and variability of stellar winds

Guerrero

Marco

2013

A&A

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The occurrence of stellar wind in the central star of a planetary nebula (CSPN) can be revealed by the presence of P Cygni profiles of high-excitation lines overimposed on its stellar continuum. We examined the entire Far-Ultraviolet Spectroscopic Explorer (FUSE) archive and merged all useful spectroscopic observations of CSPNe to produce the highest quality spectra that can be used to assess the frequency of stellar winds. Furthermore, the individual spectra of each CSPN were compared to search for variability in the P Cygni profile. P Cygni profiles of high-excitation lines have been found in 44 CSPNe, with a clear correlation between the ionization potential of the lines and the effective temperature of the star. We introduce a prescription to derive the terminal wind velocity (v ∞ ) from saturated and unsaturated P Cygni profiles and provide new values of v ∞ for these stars. Another 23 CSPNe do not show P Cygni profiles, or else their data in the FUSE archive are not conclusive enough to determine the occurrence of P Cygni profiles. Variability in the P Cygni profile of high-excitation, far-UV lines is found for the first time in six CSPNe, namely Hen 2-131, NGC 40, NGC 1535, NGC 2392, Sp 3, and SwSt 1. This increases up to 13 the number of CSPNe with variable P Cygni profiles in the UV, including those previously reported using IUE or FUSE observations. Variability is seen primarily in the unsaturated P v and Si iv lines, but also in saturated C iii and O vi lines. The CSPNe with variable P Cygni profiles have similar stellar properties (relatively low log (g) and T eff ) that suggest they are less evolved CSPNe. Some of the CSPNe with variable P Cygni profiles show O vi lines, while their effective temperature is insufficient to produce this ion. We suggest that this ion is produced by Auger ionization from X-rays associated to shocks in their stellar winds, as is the case in massive OB stars of high ionization potential ions that cannot be abundantly produced by photoionizations.

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

Guerrero

2011

Proc. IAU

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Abstract. The photospheric emission from the hottest central stars of planetary nebulae (CSPNe) is capable to extend into the X-ray domain, with emission peaking at 0.1-0.2 keV and vanishing above 0.4 keV. Unexpected, intriguing hard X-ray emission with energies greater than 0.5 keV has been reported for several CSPNe and for a number of white dwarfs (WDs). Different mechanisms may be responsible for the hard X-ray emission from CSPNe and WDs: coronal emission from a late-type companion, shocks in fast winds as in OB stars, leakage from underneath the star photosphere, or accretion of material from a disk, a companion star, or the circumstellar medium. Therefore, the hard X-ray emission associated with CSPNe may have significant implications for our understanding of the formation of PNe: binary companions, disks, and magnetic fields are thought to play a major role in the shaping of PNe, whereas clumping in the stellar wind may have notable effects in the PN evolution by modifying the stellar mechanical energy output. Here I present the results of different observational efforts to search for hard X-ray emission from CSPNe and discuss the different mechanisms for the production of hard X-rays.

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Structure and clumping in the fast wind of NGC 6543

Cited by 17 publications

References 44 publications

Non–Local Thermodynamic Equilibrium Model of NGC 6543’s Central Star and Its Relation to the Surrounding Planetary Nebula

Non–Local Thermodynamic Equilibrium Model of NGC 6543’s Central Star and Its Relation to the Surrounding Planetary Nebula

Analysis of far-UV data of central stars of planetary nebulae: Occurrence and variability of stellar winds

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

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