K2-66b is a confirmed

mega-Earth A mega-Earth is a proposed neologism for a massive terrestrial exoplanet that is at least ten times the mass of Earth. Mega-Earths would be substantially more massive than super-Earths (terrestrial and ocean planets with masses around 5–10 Earth ...

orbiting the

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution of ...

K2-66, about form Earth in the direction of

Aquarius Aquarius may refer to: Astrology * Aquarius (astrology), an astrological sign * Age of Aquarius, a time period in the cycle of astrological ages Astronomy * Aquarius (constellation) * Aquarius in Chinese astronomy Arts and entertainme ...

. It is an extremely hot and dense planet heavier than

Neptune Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...

, but with only about half its radius.

Planet properties

Mass, radius, and temperature

K2-66b is a mega-Earth with radius and mass . The planet's temperature is highly variable due to the variability of its host star, and is currently estimated at .

Orbit

The

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

orbits every 5.07 days at 0.06 AU. It orbits within a "

photoevaporation Photoevaporation denotes the process where energetic radiation ionises gas and causes it to disperse away from the ionising source. This typically refers to an astrophysical context where ultraviolet radiation from hot stars acts on clouds of mat ...

desert", where orbiting exoplanets should be very uncommon. K2-66b's orbit is nearly circular.

Star

The star, K2-66 is a G1 sub-giant in

. It has a sun-like temperature of 5887 K, which corresponds to its

spectral class In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

and is very close to that of th
rotationally variable
sta
Kepler-130
It has a radius of and a mass of . Its

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as a ...

is −0.047, and its

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...

is 11.71.

References

External links