Search

Analysis of the metallicities of more than 400 stars hosting 600 candidate extrasolar planets shows that the planets can be categorized by size into three populations — terrestrial-like planets, gas dwarf planets with rocky cores and hydrogen–helium envelopes, and ice or gas giant planets — on the basis of host star metallicity.

Whereas large planets, such as gas giants, are more likely to form around high-metallicity stars, terrestrial-sized planets are found to form around stars with a wide range of metallicities, indicating that they may be widespread in the disk of the Galaxy.

Two double-sun exoplanets have been discovered by the Kepler spacecraft, establishing a new class of ‘circumbinary’ exoplanets and suggesting that at least several million such systems exist in our Galaxy.

Two exoplanets of Earth’s size have been discovered in orbit around the star Kepler-20.

A population of extrasolar planets has been uncovered with minimum masses of 1.9–10 times the Earth's mass, called super-Earths, but atmospheric studies can be precluded by the distance and size of their stars. Here, observations of the transiting planet GJ 1214b are reported; it has a mass 6.55 times that of the Earth and a radius 2.68 times the Earth's radius. The star is small and only 13 parsecs away, permitting the study of the planetary atmosphere with current observatories.

Stellar data from the Kepler spacecraft are used to infer the existence of a sub-Mercury-sized exoplanet, the smallest yet discovered, in orbit around a Sun-like star.

A giant planet candidate roughly the size of Jupiter but more than 14 times as massive is observed by TESS and other instruments to be transiting the white dwarf star WD 1856+534.

When an extrasolar planet passes in front of its star (transits), its radius can be measured from the decrease in starlight and its orbital period from the time between transits. This study reports Kepler spacecraft observations of a single Sun-like star that reveal six transiting planets, five with orbital periods between 10 and 47 days plus a sixth one with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases.

Magnetospheres of exoplanets are vast, tenuous and hard to detect. Deep blue-shifted absorption lines observed in the extended region around HAT-P-11 b may provide evidence for a magnetosphere and magnetotail.

The giant planet KELT-9b has a dayside temperature of about 4,600 K, which is sufficiently high to dissociate molecules and to evaporate its atmosphere, owing to its hot stellar host.

Observations of the gas-giant exoplanet WASP-121b reveal near-infrared emission lines of water, suggesting that the planet has a stratosphere—a layer in the upper atmosphere where temperature increases with altitude.

Data from the Kepler spacecraft and the HARPS-N ground-based spectrograph indicate that the extrasolar planet Kepler-78b has a mean density similar to that of Earth and imply that it is composed of rock and iron.

Kepler-107 b and c have the same radius but, contrary to expectations, the outermost Kepler-107 c is much denser. This difference cannot be explained by photoevaporation by stellar high-energy particle flux and it suggests that Kepler-107 c experienced a giant impact event.