STARSPOTS-TRANSIT DEPTH RELATION OF THE EVAPORATING PLANET CANDIDATE KIC 12557548b

Kawahara, Hajime; Hirano, Teruyuki; Kurosaki, Kunihiko; Itō, Yūichi; Ikoma, Masahiro

doi:10.1088/2041-8205/776/1/l6

Cited by 45 publications

(84 citation statements)

References 48 publications

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“…It is interesting to note that depth (and apparently morphology) variations thatcorrelate with stellar rotational phase have been observed in the transits of the disintegrating planet KIC 12557548b (Kawahara et al 2013;Croll et al 2015). Additionally, Croll et al (2015) found morphological variations that correlated with the transit timing variations, such that late transits had shallower dips with a more gradual egress relative to the early or on-time transits.…”

Section: Light Curve Parameterizationmentioning

confidence: 91%

A Transient Transit Signature Associated with the Young Star RIK-210

David

Petigura

Hillenbrand

et al. 2017

ApJ

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We find transienttransit-like dimming events within the K2 time series photometry of the young star RIK-210 in the Upper Scorpius OB association. These dimming events are variable in depth, duration, and morphology. High spatial resolution imaging revealed thatthe star is singleand radial velocity monitoring indicated that the dimming events cannot be due to an eclipsing stellar or brown dwarf companion. Archival and follow-up photometry suggest the dimming events are transient in nature. The variable morphology of the dimming events suggests they are not due to a singlespherical body. The ingress of each dimming event is always shallower than egress, as one would expect for an orbiting body with a leading tail. The dimming events are periodic and synchronous with the stellar rotation. However, we argue it is unlikely the dimming events could be attributed to anything on the stellar surface based on the observed depths and durations. Variable obscuration by a protoplanetary disk is unlikely on the basis that the star is not actively accreting and lacks the infrared excess associated with an inner disk. Rather, we explore the possibilities that the dimming events are due to magnetospheric clouds, a transiting protoplanet surrounded by circumplanetary dust and debris, eccentric orbiting bodies undergoing periodic tidal disruption, or an extended field of dust or debris near the corotation radius.

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Section: Light Curve Parameterizationmentioning

confidence: 91%

A Transient Transit Signature Associated with the Young Star RIK-210

David

Petigura

Hillenbrand

et al. 2017

ApJ

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“…Perez-Becker & Chiang (2013) find that if the disintegrating planet model is correct, KIC 1255b is likely in its final stages of its existence, having already lost~70% of its mass and now being little more than an iron-nickel core. Kawahara et al (2013) find a small signal in the transit depths at the period of the rotation period of the host star, which they interpret as evidence that the evaporation is correlated with stellar magnetic activity, but which Croll et al (2015) attribute to starspots.…”

Section: Discovery and Evaporating Planet Modelmentioning

confidence: 95%

The Ĝ Search for Extraterrestrial Civilizations With Large Energy Supplies. Iv. The Signatures and Information Content of Transiting Megastructures

Wright

Cartier

Zhao

et al. 2015

ApJ

122

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Arnold, Forgan, and Korpela et al. noted that planet-sized artificial structures could be discovered with Kepler as they transit their host star. We present a general discussion of transiting megastructures, and enumerate 10 potential ways their anomalous silhouettes, orbits, and transmission properties would distinguish them from exoplanets. We also enumerate the natural sources of such signatures. Several anomalous objects, such as KIC 12557548 and CoRoT-29, have variability in depth consistent with Arnold's prediction and/or an asymmetric shape consistent with Forgan's model. Since well-motivated physical models have so far provided natural explanations for these signals, the ETI hypothesis is not warranted for these objects, but they still serve as useful examples of how nonstandard transit signatures might be identified and interpreted in a SETI context. Boyajian et al. recently announced KIC 8462852, an object with a bizarre light curve consistent with a "swarm" of megastructures. We suggest that this is an outstanding SETI target. We develop the normalized information content statistic M to quantify the information content in a signal embedded in a discrete series of bounded measurements, such as variable transit depths, and show that it can be used to distinguish among constant sources, interstellar beacons, and naturally stochastic or artificial, information-rich signals. We apply this formalism to KIC 12557548 and a specific form of beacon suggested by Arnold to illustrate its utility.

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“…The calculated mass-loss rate suggests that KIC 12557548b may be in the catastrophic end state of its life, which will destroy it entirely (Perez-Becker & Chiang 2013). Stellar activity may factor into the planet's destruction-the deepest transit depths during the Kepler observations tend to coincide with times at which the star spots face our line of sight and shallow transit depths occur when the stellar spots are rotated out of our line of sight (Kawahara et al 2013). This correlation has been confirmed with additional Kepler data, but there is also the possibility that occultations of star spots by the comet's tail affect the transit depth (Croll et al 2015b).…”

Section: Introductionmentioning

confidence: 99%

REDUCED ACTIVITY AND LARGE PARTICLES FROM THE DISINTEGRATING PLANET CANDIDATE KIC 12557548b

Schlawin

Herter

Zhao

et al. 2016

ApJ

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The intriguing exoplanet candidate KIC 12557548b is believed to have a comet-like tail of dusty debris trailing a small rocky planet. The tail of debris scatters up to 1.3% of the stellar light in the Kepler observatory's bandpass (0.42-0.9 μm). Observing the tail's transit depth at multiple wavelengths can reveal the composition and particle size of the debris, constraining the makeup and lifetime of the sub-Mercury planet. Early dust particle size predictions from the scattering of the comet-like tail pointed toward a dust size of ∼0.1 μm for silicate compositions. These small particles would produce a much deeper optical transit depth than near-infrared transit depth. We measure a transmission spectrum for KIC 12557548b using the SpeX spectrograph (covering 0.8-2.4 μm) simultaneously with the MORIS imager taking r′ (0.63 μm) photometry on the Infrared Telescope Facility for eight nights and one night in H band (1.63 μm) using the Wide-field IR Camera at the Palomar 200 inch telescope. The infrared spectra are plagued by systematic errors, but we argue that sufficient precision is obtained when using differential spectroscopic calibration when combining multiple nights. The average differential transmission spectrum is flat, supporting findings that KIC 12557548b's debris is likely composed of larger particles 0.5 μm for pyroxene and olivine and 0.2 μm for iron and corundum. The r′ photometric transit depths are all below the average Kepler value, suggesting that the observations occurred during a weak period or that the mechanisms producing optical broadband transit depths are suppressed.

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STARSPOTS-TRANSIT DEPTH RELATION OF THE EVAPORATING PLANET CANDIDATE KIC 12557548b

Cited by 45 publications

References 48 publications

A Transient Transit Signature Associated with the Young Star RIK-210

A Transient Transit Signature Associated with the Young Star RIK-210

The Ĝ Search for Extraterrestrial Civilizations With Large Energy Supplies. Iv. The Signatures and Information Content of Transiting Megastructures

REDUCED ACTIVITY AND LARGE PARTICLES FROM THE DISINTEGRATING PLANET CANDIDATE KIC 12557548b

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