Planet Candidates from K2 Campaigns 5–8 and Follow-up Optical Spectroscopy

Petigura, Erik A.; Crossfield, Ian J. M.; Isaacson, Howard; Beichman, Charles; Christiansen, Jessie L.; Dressing, Courtney D.; Fulton, Benjamin J.; Howard, Andrew W.; Kosiarek, Molly R.; Lépine, Sébastien; Schlieder, Joshua E.; Sinukoff, Evan; Yee, Samuel W.

doi:10.3847/1538-3881/aa9b83

Cited by 72 publications

(88 citation statements)

References 59 publications

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“…The bottom panel shows the full K2 observing baseline from Petigura et al (2016), and the insets show the fits to individual transit times. 9 For a more detailed discussion of K2 systematics, see Petigura et al (2018) and references therein.…”

Section: Spitzermentioning

confidence: 99%

Dynamics and Formation of the Near-resonant K2-24 System: Insights from Transit-timing Variations and Radial Velocities

Petigura

Benneke

Batygin

et al. 2018

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While planets between the size of Uranus and Saturn are absent within the solar system, the star K2-24 hosts two such planets, K2-24b and c, with radii equal to 5.4 Å R and 7.5 Å R , respectively. The two planets have orbital periods of 20.9days and 42.4days, residing only 1% outside the nominal 2:1 mean-motion resonance. In this work, we present results from a coordinated observing campaign to measure planet masses and eccentricities that combines radial velocity measurements from Keck/HIRES and transit-timing measurements from K2 and Spitzer. K2-24b and c have low, but nonzero, eccentricities of~ẽ e 0.08 1 2. The low observed eccentricities provide clues to the formation and dynamical evolution of K2-24b and K2-24c, suggesting that they could be the result of stochastic gravitational interactions with a turbulent protoplanetary disk, among other mechanisms. K2-24b and c are M , respectively; K2-24c is 20% less massive than K2-24b, despite being 40% larger. Their large sizes and low masses imply large envelope fractions, which we estimate at -+ 26 3 3 % and -+ 52 3 5 %. In particular, K2-24c's large envelope presents an intriguing challenge to the standard model of core-nucleated accretion that predicts the onset of runaway accretion when f env ≈50%.

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Section: Spitzermentioning

confidence: 99%

Dynamics and Formation of the Near-resonant K2-24 System: Insights from Transit-timing Variations and Radial Velocities

Petigura

Benneke

Batygin

et al. 2018

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“…From then on, we process the data using a photometric pipeline that has been described in detail in past works by members of our team (e.g., Crossfield et al 2015;Petigura et al 2015Petigura et al , 2018. In brief, we follow an approach similar to that originally outlined by Vanderburg & Johnson (2014).…”

Section: Time-series Photometrymentioning

confidence: 99%

“…Details of the vetting process are described in Crossfield et al (2016) and Petigura et al (2018). TERRA produces a set of diagnostics for every TCE, which we use to classify the event as a candidate planet, eclipsing binary, periodic variable, or noise.…”

Section: Triage and Vettingmentioning

confidence: 99%

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Planetary Candidates from K2 Campaign 16

Crossfield

Schlieder

et al. 2018

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Given that Campaign 16 of the K2 mission is one of just two K2 campaigns observed so far in "forward-facing" mode, which enables immediate follow-up observations from the ground, we present a catalog of interesting targets identified through photometry alone. Our catalog includes 30 high-quality planet candidates (showing no signs of being non-planetary in nature), 48 more ambiguous events that may be either planets or false positives, 164 eclipsing binaries, and 231 other regularly periodic variable sources. We have released light curves for all targets in C16 and have also released system parameters and transit vetting plots for all interesting candidates identified in this paper. Of particular interest is a candidate planet orbiting the bright F dwarf HD73344 (V=6.9, K=5.6) with an orbital period of 15 days. If confirmed, this object would correspond to a 2.56±0.18 R ⊕ planet and would likely be a favorable target for radial velocity characterization. This paper is intended as a rapid release of planet candidates, eclipsing binaries, and other interesting periodic variables to maximize the scientific yield of this campaign, and as a test run for the upcoming TESS mission, whose frequent data releases call for similarly rapid candidate identification and efficient follow up.

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“…Mann et al (2017a) derived a stellar effective temperature T eff of 6120 ± 90K using the color-temperature relations of Ramírez & Meléndez (2005) and Pinsonneault et al (2012). This estimate agrees with the value of T eff =6180 and log g = 4.51 independently derived by Petigura et al (2018) matching empirical templates to a Keck HIRES spectrum. Sousa et al (2018) derived a slightly cooler T eff of 5981±44K, log g = 4.32 ± 0.15, and [Fe/H] = +0.18 ± 0.04 (a metallicity consistent with the Praesepe mean) by a line-by-line analysis on a VLT-UVES echelle spectrum.…”

Section: Stellar Parametersmentioning

confidence: 53%

Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

Gaidos

Hirano

Mann

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We obtained high-resolution infrared spectroscopy and short-cadence photometry of the 600-800 Myr Praesepe star K2-100 during transits of its 1.67-day planet. This Neptune-size object, discovered by the NASA K2 mission, is an interloper in the "desert" of planets with similar radii on short period orbits. Our observations can be used to understand its origin and evolution by constraining the orbital eccentricity by transit fitting, measuring the spin-orbit obliquity by the Rossiter-McLaughlin effect, and detecting any extended, escaping hydrogen-helium envelope with the 10830Å line of neutral helium in the 2s 3 S triplet state. Transit photometry with 1-min cadence was obtained by the K2 satellite during Campaign 18 and transit spectra were obtained with the IRD spectrograph on the Subaru telescope. While the elevated activity of K2-100 prevented us from detecting the Rossiter-McLaughlin effect, the new photometry combined with revised stellar parameters allowed us to constrain the eccentricity to e < 0.15/0.28 with 90%/99% confidence. We modeled atmospheric escape as an isothermal, spherically symmetric Parker wind, with photochemistry driven by UV radiation that we estimate by combining the observed spectrum of the active Sun with calibrations from observations of K2-100 and similar young stars in the nearby Hyades cluster. Our non-detection (< 5.7mÅ) of a transit-associated He I line limits mass loss of a solar-composition atmosphere through a T ≤ 10000K wind to < 0.3 M ⊕ Gyr −1 . Either K2-100b is an exceptional desert-dwelling planet, or its mass loss is occurring at a lower rate over a longer interval, consistent with a core accretion-powered scenario for escape.

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Planet Candidates from K2 Campaigns 5–8 and Follow-up Optical Spectroscopy

Cited by 72 publications

References 59 publications

Dynamics and Formation of the Near-resonant K2-24 System: Insights from Transit-timing Variations and Radial Velocities

Dynamics and Formation of the Near-resonant K2-24 System: Insights from Transit-timing Variations and Radial Velocities

Planetary Candidates from K2 Campaign 16

Zodiacal exoplanets in time – X. The orbit and atmosphere of the young ‘neptune desert’-dwelling planet K2-100b

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