The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists

@article{Christiansen2018TheKS,
  title={The K2-138 System: A Near-resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists},
  author={Jessie L. Christiansen and Ian J. M. Crossfield and Geert Barentsen and Chris J. Lintott and Thomas Barclay and Brooke D. Simmons and Erik A. Petigura and Joshua E. Schlieder and Courtney D. Dressing and Andrew M. Vanderburg and Campbell Allen and Adam McMaster and Grant R. M. Miller and Marten Veldthuis and Sarah Allen and Zach Wolfenbarger and Brian Cox and Julia Zemiro and Andrew W. Howard and John H. Livingston and Evan Sinukoff and Timothy Catron and Andrew Grey and Joshua J. E. Kusch and Ivan A. Terentev and Martin Vale{\vs} and Martti H. Kristiansen},
  journal={The Astronomical Journal},
  year={2018},
  volume={155}
}
K2-138 is a moderately bright (V = 12.2, K = 10.3) main-sequence K star observed in Campaign 12 of the NASA K2 mission. It hosts five small (1.6–3.3 ) transiting planets in a compact architecture. The periods of the five planets are 2.35, 3.56, 5.40, 8.26, and 12.76 days, forming an unbroken chain of near 3:2 resonances. Although we do not detect the predicted 2–5 minute transit timing variations (TTVs) with the K2 timing precision, they may be observable by higher-cadence observations with… 
K2-138 g: Spitzer Spots a Sixth Planet for the Citizen Science System
K2 greatly extended Kepler’s ability to find new planets, but it was typically limited to identifying transiting planets with orbital periods below 40 days. While analyzing K2 data through the
An Updated Ephemeris for K2-138 d
K2-138 d (EPIC 245950175 d) is one of five planets in a chain of 3:2 mean motion resonances discovered by Christiansen et al. in K2 Campaign 12. An additional planet, confirmed with the Spitzer Space
Exoplanet characterisation in the longest known resonant chain: the K2-138 system seen by HARPS
The detection of low-mass transiting exoplanets in multiple systems brings new constraints to planetary formation and evolution processes and challenges the current planet formation theories.
K2-288Bb: A Small Temperate Planet in a Low-mass Binary System Discovered by Citizen Scientists
Observations from the Kepler and K2 missions have provided the astronomical community with unprecedented amounts of data to search for transiting exoplanets and other astrophysical phenomena. Here,
Three Small Planets Transiting the Bright Young Field Star K2-233
We report the detection of three small transiting planets around the young K3 dwarf K2-233 (2MASS J15215519−2013539) from observations during Campaign 15 of the K2 mission. The star is relatively
Confirming the 3:2 Resonance Chain of K2-138
The study of orbital resonances allows for the constraint of planetary properties of compact systems. K2-138 is an early K-type star with six planets, five of which have been proposed to be in the
Scaling K2. V. Statistical Validation of 60 New Exoplanets From K2 Campaigns 2–18
The NASA K2 mission, salvaged from the hardware failures of the Kepler telescope, has continued Kepler’s planet-hunting success. It has revealed nearly 500 transiting planets around the ecliptic
Detection of Hundreds of New Planet Candidates and Eclipsing Binaries in K2 Campaigns 0–8
We implement a search for exoplanets in campaigns zero through eight (C0–8) of the K2 extension of the Kepler spacecraft. We apply a modified version of the QATS planet search algorithm to K2 light
Six transiting planets and a chain of Laplace resonances in TOI-178
Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their
The TESS-Keck Survey. XI. Mass Measurements for Four Transiting Sub-Neptunes Orbiting K Dwarf TOI–1246
Multiplanet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf (V = 11.6, K = 9.9)
...
...

References

SHOWING 1-10 OF 63 REFERENCES
DOPPLER MONITORING OF FIVE K2 TRANSITING PLANETARY SYSTEMS
In an effort to measure the masses of planets discovered by the NASA K2 mission, we have conducted precise Doppler observations of five stars with transiting planets. We present the results of a
Eleven Multi-planet Systems from K2 Campaigns 1 & 2 and the Masses of Two Hot Super-Earths
We present a catalog of 11 multiplanet systems from Campaigns 1 and 2 of the K2 mission. We report the sizes and orbits of 26 planets split between seven two-planet systems and four three-planet
A resonant chain of four transiting, sub-Neptune planets
TLDR
The architecture of Kepler-223 is too finely tuned to have been formed by scattering, and numerical simulations demonstrate that its properties are natural outcomes of the migration hypothesis.
A seven-planet resonant chain in TRAPPIST-1
The TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit
Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets
HD 3167 is a bright (V = 8.9), nearby K0 star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site,
A DYNAMICAL ANALYSIS OF THE KEPLER-80 SYSTEM OF FIVE TRANSITING PLANETS
Kepler has discovered hundreds of systems with multiple transiting exoplanets which hold tremendous potential both individually and collectively for understanding the formation and evolution of
A Multi-planet System Transiting the V = 9 Rapidly Rotating F-Star HD 106315
We report the discovery of a multi-planet system orbiting HD 106315, a rapidly rotating mid F-type star, using data from the K2 mission. HD 106315 hosts a 2.51 ± 0.12 R⊕ sub-Neptune in a 9.5-day
Transit Timing Variation of Near-Resonance Planetary Pairs. II. Confirmation of 30 planets in 15 Multiple Planet Systems
Following on from Paper I in this series, I report the confirmation of a further 30 planets in 15 multiple-planet systems via transit timing variations (TTVs), using the publicly available Kepler
Two Small Transiting Planets and a Possible Third Body Orbiting HD 106315
The masses, atmospheric makeups, spin–orbit alignments, and system architectures of extrasolar planets can be best studied when the planets orbit bright stars. We report the discovery of three bodies
TWO SMALL PLANETS TRANSITING HD 3167
We report the discovery of two super-Earth-sized planets transiting the bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected by the K2 mission. The inner planet, HD 3167 b,
...
...