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

Jevtić, N.; Stine, P.; Nilsen, Wayne; Schweitzer, J.S.; Jenkins, Jon M.; Klaus, Todd C.; Lie, Ji; McCauliff, Sean

doi:10.1088/0004-637x/756/1/9

Cited by 8 publications

(12 citation statements)

References 28 publications

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“…We also measured a weak radial velocity variability with a best period of 0.238 days (which is equivalent to one fifth of the 1.236 day periodcity), using measurements from the catalogue of Acker et al (1982). We discuss this peculiar behaviour further in § 8.3 where we compare our measurements with those of Jevtić et al (2012) and Handler et al (2013).…”

Section: The Analysis Of Ngc 6826mentioning

confidence: 91%

Identifying close binary central stars of PN with Kepler

Marco

Long

Jacoby

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Six planetary nebulae (PN) are known in the Kepler space telescope field of view, three newly identified. Of the 5 central stars of PN with useful Kepler data, one, J 193110888+4324577, is a short-period, post common envelope binary exhibiting relativistic beaming effects. A second, the central star of the newly identified PN Pa 5, has a rare O(He) spectral type and a periodic variability consistent with an evolved companion, where the orbital axis is almost aligned with the line of sight. The third PN, NGC 6826 has a fast rotating central star, something that can only be achieved in a merger. Fourth, the central star of the newly identified PN Kn 61, has a PG1159 spectral type and a mysterious semi-periodic light variability which we conjecture to be related to the interplay of binarity with a stellar wind. Finally, the central star of the circular PN A 61 does not appear to have a photometric variability above 2 mmag. With the possible exception of the variability of Kn 61, all other variability behaviour, whether due to binarity or not, would not easily have been detected from the ground. We conclude, based on very low numbers, that there may be many more close binary or close binary products to be discovered with ultra-high precision photometry. With a larger number of high precision photometric observations we will be able to determine how much higher than the currently known 15 per cent, the short period binary fraction for central stars of PN is likely to be.

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Section: The Analysis Of Ngc 6826mentioning

confidence: 91%

Identifying close binary central stars of PN with Kepler

Marco

Long

Jacoby

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…Recently,Douchin et al (2012) list NGC 6826 as a possible binary with a period of 0.619 days, butJevtić et al (2012) after a year of continuos observing with Kepler find only stochastic brightness variations in the central star of NGC 6826 Prinja, Massa & Cantiello (2012). consider that these brightness variations found byJevtić et al (2012) in the central star of NGC 6828 are possibly related to subsurface convective layers, just as the ones they have found in the -22central star of NGC 6543 and where they derive a high rotational velocity for the central star. High stellar rotation in the central star of a PN may be an indication of spin-up by a past merger, tidal interaction or mass accretion in a binary system.…”

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confidence: 99%

A Detailed Morpho-Kinematic Model of the Eskimo, NGC 2392: A Unifying View With the Cat's Eye and Saturn Planetary Nebulae

García-Díaz

López

Steffen

et al. 2012

ApJ

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The 3-D and kinematic structure of the Eskimo nebula, NGC 2392, has been notoriously difficult to interpret in detail given its complex morphology, multiple kinematic components and its nearly pole-on orientation along the line of sight.We present a comprehensive, spatially resolved, high resolution, long-slit spectroscopic mapping of the Eskimo planetary nebula. The data consist of 21 spatially resolved, long-slit echelle spectra tightly spaced over the Eskimo and along its bipolar jets. This data set allows us to construct a velocity-resolved [NII] channel map of the nebula with a resolution of 10 km s −1 that disentangles the different kinematic components of the nebula. The spectroscopic information is combined with HST images to construct a detailed three dimensional morpho-kinematic model of the Eskimo using the code SHAPE. With this model we demonstrate that the Eskimo is a close analog to the Saturn and the Cat's Eye nebulae, but rotated 90 • to the line of sight. Furthermore, we show that the main characteristics of our model apply to the general properties of the group of elliptical planetary nebulae with ansae or FLIERS, once the orientation is considered. We conclude that these kind of nebulae belongs to a class with a complex common evolutionary sequence of events.

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“…The effective noise reduction shown in Fig. 4 for the Q1 LC KIC 12071221 light curves even though no comb of frequencies is observable persists in all the quarters 1-4 as can Comparison of LC power spectra for Q1 for KIC 12071221 that have no pronounced lines prior to noise reduction (gray) and after nonlinear noise reduction (black) (from Jevtić et al 2012). be seen in Table 1.…”

Section: Case 2: No Observable Fundamental or Harmonics Kic 12071221 mentioning

confidence: 86%

“…The time delay d for light curves is chosen at a minimum of the AMI. Jevtić et al (2005Jevtić et al ( , 2012) present a detailed discussion on AMI. This time delay d is an integer number of sampling intervals.…”

Section: Nonlinear Time Series Analysismentioning

confidence: 99%

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Nonlinear time series analysis of Kepler Space Telescope data: Mutually beneficial progress

2012

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Nonlinear time series analysis, though a powerful tool, has not been used widely in astronomy and astrophysics because the principle requirements that the data be sampled uniformly and continuous are rarely met. Kepler Space Telescope variable-star light curves satisfy these and almost all other requirements. These data have allowed a more systematic study of the methodology and yielded new information. Nonlinear noise reduction is the aspect we focus on here. Nonlinear time series power spectra often have relevant information across all the frequencies in a spectrum. As opposed to traditional filtering that results in a loss of information at the high frequencies, nonlinear local projective noise reduction allows us to significantly reduce noise while keeping high-frequency information. Nonlinear noise reduction is discussed for a number of Kepler Space Telescope targets with different power-spectral characteristics. The extremely high quality of the Kepler data has also allowed us to explore the novel use of average mutual information (AMI) for distinguishing signal from noise in broadband spectra. We report on noise reduction for targets with power spectra that contain a fundamental and harmonics, power spectra with no such lines and spectra with high-frequency lines.

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

Cited by 8 publications

References 28 publications

Identifying close binary central stars of PN with Kepler

Identifying close binary central stars of PN with Kepler

A Detailed Morpho-Kinematic Model of the Eskimo, NGC 2392: A Unifying View With the Cat's Eye and Saturn Planetary Nebulae

Nonlinear time series analysis of Kepler Space Telescope data: Mutually beneficial progress

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