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HD 40307

31 May 2018, 13:04 UTC
HD 40307

K2-138 is the first extrasolar system whose planets were discovered by citizen scientists participating in the Exoplanet Explorers project on the Zooniverse platform. With a visual magnitude of 12.2, it is about 300 times too faint to be visible the naked eye.

 

The central star is a orange dwarf star (K1V spectral type) with a radius and a mass respectively about 86% and 93% of those of the Sun. Its temperature is 5100 °C, slightly smaller than the Sun’s 5500 °C. 

 

The five planets were discovered in 2018 thanks to the observation of their transits by the Kepler space telescope. All the planets are sub-Neptunes, with radii between 1.5 and 3.3 times that of the Earth. Each pair of planet is in or close to a 3:2 resonance, i.e. each planet does exactly or nearly exactly 2 orbits around the star when the planet just closer does 3.

Mass(MJ)
Radius (RJ)
Period (days)
Discovery

K2-138b

0.14
2.35
2018

K2-138c

0.23
3.56
2018

K2-138d

0.24
5.40
2018

K2-138e

0.29
8.26
2018

K2-138f

0.25
12.76
2018

The post HD 40307 appeared first on NCCR PlanetS.

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