The census of exoplanets is incomplete for orbital distances larger than 1 AU. Here, we present 41long-period planet candidates in 38systems identified by Planet Hunters based on Kepler archival data (Q0-Q17). Among them, 17exhibit only one transit, 14have two visible transits, and 10have more than three visible transits. For planet candidates with only one visible transit, we estimate their orbital periods based on transit duration and host star properties. The majority of the planet candidates in this work (75%) have orbital periods that correspond to distances of 1-3 AU from their host stars. We conduct follow-up imaging and spectroscopic observations to validate and characterize planet host stars. In total, we obtain adaptive optics images for 33stars to search for possible blending sources. Six stars have stellar companions within 4″. We obtain high-resolution spectra for 6stars to determine their physical properties. Stellar properties for other stars are obtained from the NASA Exoplanet Archive and the Kepler Stellar Catalog by Huber et al. We validate 7 planet candidates that have planet confidence over 0.997 (3σ level). These validated planets include 3 single-transit planets (KIC-3558849b, KIC5951458b, and KIC-8540376c), 3 planets with double transits (KIC-8540376b, KIC-9663113b, and KIC10525077b), and 1 planet with four transits (KIC-5437945b). This work provides assessment regarding the existence of planets at wide separations and the associated false positive rate for transiting observation (17%-33%). More than half of the long-period planets with at least three transits in this paper exhibit transit timing variations up to 41 hr, which suggest additional components that dynamically interact with the transiting planet candidates. The nature of these components can be determined by follow-up radial velocity and transit observations.

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 R Å ) 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, for example, Spitzer or CHEOPS. The planets are amenable to mass measurement by precision radial velocity measurements, and therefore K2-138 could represent a new benchmark system for comparing radial velocity and TTV masses. K2-138 is the first exoplanet discovery by citizen scientists participating in the Exoplanet Explorers project on the Zooniverse platform.

In this paper we present a catalog of 4584 eclipsing binaries observed during the first two years (26 sectors) of the TESS survey. We discuss selection criteria for eclipsing binary candidates, detection of hitherto unknown eclipsing systems, determination of the ephemerides, the validation and triage process, and the derivation of heuristic estimates for the ephemerides. Instead of keeping to the widely used discrete classes, we propose a binary star morphology classification based on a dimensionality reduction algorithm. Finally, we present statistical properties of the sample, we qualitatively estimate completeness, and we discuss the results. The work presented here is organized and performed within the TESS Eclipsing Binary Working Group, an open group of professional and citizen scientists; we conclude by describing ongoing work and future goals for the group. The catalog is available from http://tessEBs.villanova.edu and from MAST.

Using Campaign 15 data from the K2 mission, we have discovered a triply-eclipsing triple star system: EPIC 249432662. The inner eclipsing binary system has a period of 8.23 days, with shallow ∼3% eclipses. During the entire 80-day campaign, there is also a single eclipse event of a third-body in the system that reaches a depth of nearly 50% and has a total duration of 1.7 days, longer than for any previously known thirdbody eclipse involving unevolved stars. The binary eclipses exhibit clear eclipse timing variations. A combination of photodynamical modeling of the lightcurve, as well as seven follow-up radial velocity measurements, has led to a prediction of the subsequent eclipses of the third star with a period of 188 days. A campaign of follow-up groundbased photometry was able to capture the subsequent pair of third-body events as well as two further 8-day eclipses. A combined photo-spectro-dynamical analysis then leads to the determination of many of the system parameters. The 8-day binary consists of a pair of M stars, while most of the system light is from a K star around which the pair of M stars orbits.1 In this paper, we use the following notations. The orbital elements of the inner and outer orbits are subscripted by numbers '1' and '2', respectively. Regarding the three stars, we label them as A, Ba, and Bb, where A denotes the brightest and most massive component, i.e., the distant, third star, while Ba and Bb refer to the primary and the secondary components of the close, inner 8-day binary. When we refer to physical quantities of individual stars, we use these subscripts. In such a way, for example, m A or m Ba stands for the masses of components A or Ba, respectively, but m B denotes the total mass of the inner binary, (m Ba + m Bb ), while m AB refers to the total mass of the entire triple system.

Exoplanets can evolve significantly between birth and maturity, as their atmospheres, orbits, and structures are shaped by their environment. Young planets (<1 Gyr) offer an opportunity to probe the critical early stages of this evolution, where planets evolve the fastest. However, most of the known young planets orbit prohibitively faint stars. We present the discovery of two planets transiting HD 63433 (TOI 1726, TIC 130181866), a young Sun-like ( =  M 0.99 0.03 * ) star. Through kinematics, lithium abundance, and rotation, we confirm that HD 63433 is a member of the Ursa Major moving group (τ=414±23 Myr). Based on the TESS light curve and updated stellar parameters, we estimate that the planet radii are 2.15±0.10 R ⊕ and 2.67±0.12 R ⊕ , the orbital periods are 7.11