Binary Central Stars of Planetary Nebulae Identified With Kepler/K2. (arXiv:2104.07934v3 [astro-ph.SR] UPDATED)

Binary Central Stars of Planetary Nebulae Identified With Kepler/K2. (arXiv:2104.07934v3 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Jacoby_G/0/1/0/all/0/1">George H. Jacoby</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hillwig_T/0/1/0/all/0/1">Todd C. Hillwig</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jones_D/0/1/0/all/0/1">David Jones</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martin_K/0/1/0/all/0/1">Kayla Martin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marco_O/0/1/0/all/0/1">Orsola De Marco</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kronberger_M/0/1/0/all/0/1">Matthias Kronberger</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hurowitz_J/0/1/0/all/0/1">Jonathan L. Hurowitz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crocker_A/0/1/0/all/0/1">Alison F. Crocker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dey_J/0/1/0/all/0/1">Josh Dey</a>

We present the identification of 34 likely binary central stars (CSs) of
planetary nebulae (PNe) from {it Kepler/K2} data, seven of which show
eclipses. Of these, 29 are new discoveries. Two additional CSs with more
complicated variability are also presented. We examined the light curves of all
`possible’, `likely’ and `true’ PNe in every {it Kepler/K2} campaign (0
through 19) to identify CS variability that may indicate a binary CS. For
Campaigns 0, 2, 7, 15, and 16 we find 6 likely or confirmed variables among 21
PNe. Our primary effort, though, was focused on Campaign 11 which targeted a
Galactic bulge field containing approximately 183 PNe, in which we identified
30 candidate variable CSs. The periods of these variables range from 2.3~h to
30~d, and based on our analysis, most are likely to be close binary star
systems. We present periods and preliminary classifications (eclipsing, double
degenerate, or irradiated systems) for the likely binaries based on light curve
shape. From our total sample of 204 target PNe, with a correction for
incompleteness due to magnitude limits, we calculate a binary fraction of PN
central stars to be 20.7 percent for all the observed PNe, or 23.5 percent if
we limit our sample only to `true’ PNe. However these fractions are almost
certainly lower limits due to the large angular size of the emph{Kepler}
pixels, which leads to reduced sensitivity in detecting variability, primarily
as a result of dilution and noise from the nebula and neighbouring stars. We
discuss the binary population of CSs based on these results as part of the
total known sample of close binary CSs.

We present the identification of 34 likely binary central stars (CSs) of
planetary nebulae (PNe) from {it Kepler/K2} data, seven of which show
eclipses. Of these, 29 are new discoveries. Two additional CSs with more
complicated variability are also presented. We examined the light curves of all
`possible’, `likely’ and `true’ PNe in every {it Kepler/K2} campaign (0
through 19) to identify CS variability that may indicate a binary CS. For
Campaigns 0, 2, 7, 15, and 16 we find 6 likely or confirmed variables among 21
PNe. Our primary effort, though, was focused on Campaign 11 which targeted a
Galactic bulge field containing approximately 183 PNe, in which we identified
30 candidate variable CSs. The periods of these variables range from 2.3~h to
30~d, and based on our analysis, most are likely to be close binary star
systems. We present periods and preliminary classifications (eclipsing, double
degenerate, or irradiated systems) for the likely binaries based on light curve
shape. From our total sample of 204 target PNe, with a correction for
incompleteness due to magnitude limits, we calculate a binary fraction of PN
central stars to be 20.7 percent for all the observed PNe, or 23.5 percent if
we limit our sample only to `true’ PNe. However these fractions are almost
certainly lower limits due to the large angular size of the emph{Kepler}
pixels, which leads to reduced sensitivity in detecting variability, primarily
as a result of dilution and noise from the nebula and neighbouring stars. We
discuss the binary population of CSs based on these results as part of the
total known sample of close binary CSs.

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