An independent planet search in the<i>Kepler</i>dataset

Ofir, A.; Dreizler, S.

doi:10.1051/0004-6361/201219877

Cited by 65 publications

(62 citation statements)

References 44 publications

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“…I use a T B vs. period distribution as a means to identify remaining false positives. I find that KOI 2272.01 (see also Ofir & Dreizler 2013), 2545.01 and 2636.01 are likely diluted eclipsing binaries. Among the 27 KOIs resulting from this geometric albedo based selection, 4 only have periods longer than 4 days and all have total albedos < 1.…”

Section: False Positive Assessment and Occultationmentioning

confidence: 75%

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

Demory

2014

ApJ

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Exoplanet research focusing on the characterization of super-Earths is currently limited to those handful targets orbiting bright stars that are amenable to detailed study. This Letter proposes to look at alternative avenues to probe the surface and atmospheric properties of this category of planets, known to be ubiquitous in our galaxy. I conduct Markov Chain Monte Carlo lightcurve analyses for 97 Kepler close-in R P 2.0R ⊕ super-Earth candidates with the aim to detect their occultations at visible wavelengths. Brightness temperatures and geometric albedos in the Kepler bandpass are constrained for 27 super-Earth candidates. A hierarchical Bayesian modeling approach is then employed to characterize the population-level reflective properties of these close-in super-Earths. I find median geometric albedos A g in the Kepler bandpass ranging between 0.16 and 0.30, once decontaminated from thermal emission. These super-Earths geometric albedos are statistically larger than for hot Jupiters, which have medians A g ranging between 0.06 and 0.11. A subset of objects, including Kepler-10b, exhibit significantly larger albedos (A g 0.4). I argue that a better understanding of the incidence of stellar irradiation on planetary surface and atmospheric processes is key to explain the diversity in albedos observed for close-in super-Earths.

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Section: False Positive Assessment and Occultationmentioning

confidence: 75%

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

Demory

2014

ApJ

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“…These resources are hardly commonly available, so if one wishes to make an independent search for transiting planets in the Kepler dataset (e.g. Ofir & Dreizler 2013) one should try to use the available resources efficiently. In this paper we show that by assuming Keplerian dynamics one can simultaneously reduce the computation time by two to (almost) three orders of magnitude and improve the sensitivity for shallow transit signals.…”

Section: Discussionmentioning

confidence: 99%

“…This is best seen by looking at the local scatter of the BLS trend curve; -the highest peak (at f = 2.615 × 10 −3 d −1 ) is the first harmonic of of the 191d planet candidate reported by Ofir & Dreizler (2013). Notably, the width of the peak is a few times 10 −6 d −1 (panel c).…”

Section: Normalizationmentioning

confidence: 94%

Optimizing the search for transiting planets in long time series

Ofir

2014

A&A

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Context. Transit surveys, both ground-and space-based, have already accumulated a large number of light curves that span several years. Aims. The search for transiting planets in these long time series is computationally intensive. We wish to optimize the search for both detection and computational efficiencies. Methods. We assume that the searched systems can be described well by Keplerian orbits. We then propagate the effects of different system parameters to the detection parameters. Results. We show that the frequency information content of the light curve is primarily determined by the duty cycle of the transit signal, and thus the optimal frequency sampling is found to be cubic and not linear. Further optimization is achieved by considering duty-cycle dependent binning of the phased light curve. By using the (standard) BLS, one is either fairly insensitive to long-period planets or less sensitive to short-period planets and computationally slower by a significant factor of ∼330 (for a 3 yr long dataset). We also show how the physical system parameters, such as the host star's size and mass, directly affect transit detection. This understanding can then be used to optimize the search for every star individually. Conclusions. By considering Keplerian dynamics explicitly rather than implicitly one can optimally search the BLS parameter space. The presented Optimal BLS enhances the detectability of both very short and very long period planets, while allowing such searches to be done with much reduced resources and time. The Matlab/Octave source code for Optimal BLS is made available.

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“…A5 -mid panel). Ofir & Dreizler (2013) proposed that such behavior is caused by pulsations, rather than transits or eclipses. Further we discovered that these additional features of the light curve slightly shifted in phase during the Kepler observations.…”

Section: Exoplanet Candidate Kic9030447mentioning

confidence: 99%

Search for circum‐planetary material and orbital period variations of short‐period Kepler exoplanet candidates

et al. 2014

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A unique short-period (P = 0.65356(1) d) Mercury-size Kepler exoplanet candidate KIC012557548b has been discovered recently by Rappaport et al. (2012). This object is a transiting disintegrating exoplanet with a circum-planetary material-comet-like tail. Close-in exoplanets, like KIC012557548b, are subjected to the greatest planet-star interactions. This interaction may have various forms. In certain cases it may cause formation of the comet-like tail. Strong interaction with the host star, and/or presence of an additional planet may lead to variations in the orbital period of the planet. Our main aim is to search for comet-like tails similar to KIC012557548b and for long-term orbital period variations. We are curious about frequency of comet-like tail formation among short-period Kepler exoplanet candidates. We concentrate on a sample of 20 close-in candidates with a period similar to KIC012557548b from the Kepler mission. We first improved the preliminary orbital periods and obtained the transit light curves. Subsequently we searched for the signatures of a circum-planetary material in these light curves. For this purpose the final transit light curve of each planet was fitted with a theoretical light curve, and the residuals were examined for abnormalities. We then searched for possible long-term changes of the orbital periods using the method of phase dispersion minimization. In 8 cases out of 20 we found some interesting peculiarities, but none of the exoplanet candidates showed signs of a comet-like tail. It seems that the frequency of comet-like tail formation among short-period Kepler exoplanet candidates is very low. We searched for comet-like tails based on the period criterion. Based on our results we can conclude that the short-period criterion is not enough to cause comet-like tail formation. This result is in agreement with the theory of the thermal wind and planet evaporation (PerezBecker & Chiang 2013). We also found 3 cases of candidates which showed some changes of the orbital period. Based on our results we can see that orbital period changes are not caused by comet-like tail disintegration processes, but rather by possible massive outer companions.

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An independent planet search in theKeplerdataset

Cited by 65 publications

References 44 publications

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

THE ALBEDOS OF KEPLER' S CLOSE-IN SUPER-EARTHS

Optimizing the search for transiting planets in long time series

Search for circum‐planetary material and orbital period variations of short‐period Kepler exoplanet candidates

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