The planetary nebula NGC 6826

Feibelman, W. A.

doi:10.1086/130914

Cited by 7 publications

(5 citation statements)

References 6 publications

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“…7 × 8. 7 (Feibelman 1981), an outer ring of 36 × 36 (Coleman et al 1975), and a halo with a diameter of 142 (Millikan 1974). The inner ring is formed by a fast wind into the earlier expelled material, with a resulting hot interior bubble which pushes the older gas ahead of it to form a bright rim.…”

Section: Ngc 6826 With Its Cspn Kic 12071221mentioning

confidence: 99%

Stochastic Brightness Variations in the Central Star of Planetary Nebula NGC 6826

Jevtić

Stine

Nilsen

et al. 2012

ApJ

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One year of continuous Kepler Space Telescope data for the central object of planetary nebula NGC 6826 (KIC 12071221) were analyzed. KIC 12071221 has long-cadence light curves with stochastic brightness variations and broadband power spectra. The exception is a one-month long period during which variability was detected with a period of 14.8 hr. In search of the origin of this periodicity and in an attempt to better understand the complex NGC 6826 system, long-cadence KIC 12071221 data were analyzed using nonlinear time series methods. Nonlinear projective noise reduction from a phase-space dimension of six lowered the tail of the power spectra at the higher frequencies by factors of 38-133, an unexpected result for light curves with no obvious dominant frequencies. Even more notable is the identification of a structured distribution of trajectories, or coherence, in the reconstructed phase space for vectors spanning an interval of 1.5 hr. Organization weakens as the delay increases and is lost for phase-space vectors spanning times longer than 10 hr. This may be indicative of a binary object which shares a common envelope and/or pulsations but for a complete understanding one or both may have to be combined with wind structure. Thus, an estimate is made of the timescale of the response to what we propose is stochastic driving. This estimate of the timescale of the organized response is made by monitoring the loss of structure in the distribution of trajectories in phase space, a novel application of nonlinear methodology that may be used on data sampled with any sampling time.

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Section: Ngc 6826 With Its Cspn Kic 12071221mentioning

confidence: 99%

Stochastic Brightness Variations in the Central Star of Planetary Nebula NGC 6826

Jevtić

Stine

Nilsen

et al. 2012

ApJ

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“…Kohoutek (1979) identified the central star of PN Sh 2-71 8 to be the bright (V ∼ 13.5 mag) object slightly east of the PN's center, and measured this object to have a light variation with an amplitude of ∼0.7 mag. Feibelman (1999) detected a variable Mg II line at 2800 Å and concluded that the variability is either caused by the orbiting hot companion or by star spots on the cooler star. However, noticed a hot star in the geometric center of the PN with a magnitude consistent with it being the central star (considering published values for the distance and reddening to this PN).…”

Section: A3 Other Photmetrically-variable Objectsmentioning

confidence: 99%

Binary Central Stars of Planetary Nebulae Discovered Through Photometric Variability. I. What We Know and What We Would Like to Find Out

Marco

Hillwig

Smith

2008

The Astronomical Journal

106

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Shaping axisymmetric planetary nebulae is easier if a companion interacts with a primary at the top of the asymptotic giant branch. To determine the impact of binarity on planetary nebula formation and shaping, we need to determine the central star of planetary nebula binary fraction and period distribution. The short-period binary fraction has been known to be 10-15% from a survey of ∼100 central stars for photometric variability indicative of irradiation effects, ellipsoidal variability, or eclipses. This survey technique is known to be biased against binaries with long periods and this fact is used to explain why the periods of all the binaries discovered by this survey are smaller than 3 days. In this paper we assess the status of knowledge of binary central stars discovered because of irradiation effects. We determine that, for average parameters, this technique should be biased against periods longer than 1-2 weeks, so it is surprising that no binaries were found with periods longer than 3 days. Even more puzzling is the fact that 9 out of 12 of the irradiated binaries have periods smaller than 1 day, a fact that is starkly at odds with post-common envelope predictions. We suggest that either all common envelope models tend to overestimate post-common envelope periods or this binary survey might have suffered from additional, unquantified biases. If the latter hypothesis is true, the currently known short-period binary fraction is put in serious doubt. We also introduce a new survey for binary-related variability, which will enable us to better quantify biases and determine an independent value for the short-period binary fraction.

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“…The very high effective temperature of the ionizing source of 129 000 K was determined by Preite-Martinez et al (1989) and confirmed by (Kaler et al, 1990 andBohigas, 2001). Feibelman (1999) showed a variable Mg II λ 2800 emission line superposed on a variable stellar continuum. Jurcsik (1993) revealed the periodical light variations of the central star with the period of 68.064 d, variations of the colours in UBV(RI) C system she found insignificant.…”

Section: Introductionmentioning

confidence: 66%

“…3. Unpublished VRI CCD photometry made by M. Zejda, P. Hájek, O. Pejcha, J.Šafář, P. Sobotka at Brno in1999 -2002 and Vyškov Observatories in 2001 -2002…”

mentioning

confidence: 99%

Preliminary Analysis of Photometric Variations of the Central Star of the Planetary Nebula Sh 2–71

Mikulášek

Kohoutek

Zejda

et al.

Zdeněk Kopal’s Binary Star Legacy

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The planetary nebula NGC 6826

Abstract: NGC 6826 is established as one of only three known triple-shell, "giant halo" type planetary nebulae. Some confusing errors concerning its size and structure in the recent literature are discussed.

Cited by 7 publications

References 6 publications

Stochastic Brightness Variations in the Central Star of Planetary Nebula NGC 6826

Stochastic Brightness Variations in the Central Star of Planetary Nebula NGC 6826

Binary Central Stars of Planetary Nebulae Discovered Through Photometric Variability. I. What We Know and What We Would Like to Find Out

Preliminary Analysis of Photometric Variations of the Central Star of the Planetary Nebula Sh 2–71

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