K2-157b
K2-157b (previously designated EPIC 201130233.01) is a small Earth-sized exoplanet, likely rocky, orbiting a Sun-like star. Discovered by the Kepler space telescope during its K2 “Second Light” mission, K2-157b was validated alongside 94 other planets in February 2018. It has an extremely short orbital period of about 9 hours, one of the shortest of any known exoplanet and similar to that of K2-141b and Kepler-78b. Therefore, despite being very similar in size to Earth, it is far too hot to support life.[1]
Characteristics
Mass, radius, and temperature
K2-157b was detected using the transit method, where a planet passes in front of its star and blocks a tiny fraction of its light. Therefore, the only well-determined physical characteristic of this planet is its radius, which is notable for being close to that of Earth. K2-157b is 1.06+0.15
−0.10 R⊕, or about 6% larger than Earth.[1] This means that the planet is most likely terrestrial in nature. However, K2-157b is very close to its host star and as a result is extremely hot. The planet’s equilibrium temperature is around 2,273 K (2,000 °C; 3,632 °F), far above the melting point of iron.[2]
Orbit
K2-157b is notable for having one of the shortest and closest orbits of any known exoplanet. One full orbit takes a mere 0.365 days (about 8.8 hours) to complete.[1] The planet orbits at an average distance of about 0.0098 AU, less than 1% the distance between Earth and the Sun. For comparison, the innermost planet in our Solar System, Mercury, takes 88 days to orbit the Sun at a distance of 0.38 AU.
Host star
K2-157b orbits the Sun-like star K2-157. It is about 88% the radius and 94% the mass of the Sun. It has a temperature of 5456 K and a currently unknown age. For comparison, the Sun has a temperature of 5778 K and is 4.5 billion years old. K2-157 is relatively metal-rich, with a metallicity of about +0.13 [Fe/H].[1]
See also
References
- ↑ 1.0 1.1 1.2 1.3 "Archived Copy" (PDF). Archived from the original (PDF) on 2018-03-24. Retrieved 2018-03-20.CS1 maint: Archived copy as title (link)
- ↑ "Archived Copy". Archived from the original on 2019-09-05. Retrieved 2018-03-20.CS1 maint: Archived copy as title (link)
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