Trevor J. David

A Neptune-sized transiting planet closely orbiting a 5–10-million-year-old star

Theories of the formation and early evolution of planetary systems postulate that planets are born in circumstellar disks, and undergo radial migration during and after dissipation of the dust and gas disk from which they formed. The precise ages of meteorites indicate that planetesimals—the building blocks of planets—are produced within the first million years of a star’s life. Fully formed planets are frequently detected on short orbital periods around mature stars. Some theories suggest that the in situ formation of planets close to their host stars is unlikely and that the existence of such planets is therefore evidence of large-scale migration. Other theories posit that planet assembly at small orbital separations may be common. Here we report a newly born, transiting planet orbiting its star with a period of 5.4 days. The planet is 50 per cent larger than Neptune, and its mass is less than 3.6 times that of Jupiter (at 99.7 per cent confidence), with a true mass likely to be similar to that of Neptune. The star is 5–10 million years old and has a tenuous dust disk extending outward from about twice the Earth–Sun separation, in addition to the fully formed planet located at less than one-twentieth of the Earth–Sun separation.

The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets

Age determination is undertaken for nearby early type (BAF) stars, which constitute attractive targets for high-contrast debris disk and planet imaging surveys. Our analysis sequence consists of acquisition of uvbyβ photometry from catalogs, correction for the effects of extinction, interpolation of the photometry onto model atmosphere grids from which atmospheric parameters are determined, and finally, comparison to the theoretical isochrones from pre-main sequence through post-main sequence stellar evolution models, accounting for the effects of stellar rotation. We calibrate and validate our methods at the atmospheric parameter stage by comparing our results to fundamentally determined T_(eff) and log g values. We validate and test our methods at the evolutionary model stage by comparing our results on ages to the accepted ages of several benchmark open clusters (IC 2602, α Persei, Pleiades, Hyades). Finally, we apply our methods to estimate stellar ages for 3493 field stars, including several with directly imaged exoplanet candidates.

K2 DISCOVERY OF YOUNG ECLIPSING BINARIES IN UPPER SCORPIUS: DIRECT MASS AND RADIUS DETERMINATIONS FOR THE LOWEST MASS STARS AND INITIAL CHARACTERIZATION OF AN ECLIPSING BROWN DWARF BINARY

We report the discovery of three low-mass double-lined eclipsing binaries in the pre-main sequence Upper Scorpius association, revealed by

Rotation in the Pleiades with K2. III. Speculations on origins and evolution

K2

NEW PLEIADES ECLIPSING BINARIES AND A HYADES TRANSITING SYSTEM IDENTIFIED BY K2

photometric monitoring of the region over

Discovery of a Low-mass Companion Around HR 3549

\sim

New Low-mass Eclipsing Binary Systems in Praesepe Discovered by K2

78 days. The orbital periods of all three systems are

K2 Discovers a Busy Bee: An Unusual Transiting Neptune Found in the Beehive Cluster

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HII 2407: An eclipsing binary revealed by K2 observations of the Pleiades

5 days. We use the

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

K2