Astronomers have discovered a ‘super-Earth’ exoplanet orbiting a Sun-like star 473 light-years from Earth.
An artist’s impression of the super-Earth K2-265b. Image credit: Sci-News.com.
The newly-discovered super-Earth, named K2-265b, is 1.7 times the size of Earth, but it’s 6.5 times as massive.
This corresponds to a bulk density of 7.1 g/cm3, which is slightly higher than that of our planet’s density.
K2-265b was found using the transit method by Technical University of Berlin astronomer Kristine Wai Fun Lam and colleagues.
“Super-Earths are absent in our own Solar System. Therefore, they are of particular interest in the study of planet formation and evolution,” they said.
“To probe the formation histories of these small planets, it is necessary to derive the planetary masses and radii with precision better than a few percent in order to differentiate their internal compositions in the context of planet evolution models.”
K2-265b’s host is a 6-billion-year-old bright star of spectral type G8V, designated K2-265 (also known as EPIC 206011496 and BD-15 6276).
The super-Earth has an orbital period of just 2.4 days and is much closer to the star than our planet is to the Sun.
The planet’s surface temperature reaches 1,890 degrees Fahrenheit (1,030 degrees Celsius), which is hot enough to boil any liquid reservoirs away.
“Due to its close proximity to the host star, K2-265b is exposed to strong stellar irradiation. The planet’s atmosphere could be evaporated as a result,” the astronomers said.
“Given the high equilibrium temperature of the planet, water would be in the gaseous and supercritical phases, which are less dense than the liquid phase.”
The discovery will be described in the journal Astronomy & Astrophysics.
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K.W.F. Lam et al. 2018/ K2-265 b: A Transiting Rocky Super-Earth. A&A, in press; arXiv: 1809.08869
