GJ 3998 is a planetary system about 58 light-years away in the constellation Ophiuchus. Its magnitude, 10.8, implies that you need at least a small telescope to see it. It is made of a star and at least two planets. The planets were discovered thanks to HARPS-N and announced in 2016.
The star is a red dwarf of spectral type M1 whose radius and mass are about half of those of the Sun. Its temperature is about 3720 kelvins (3450 °C) and its metallicity (relative content of elements heavier than hydrogen and helium) is about 70% of that of the Sun.
GJ 3998 b is the innermost of the two planets. It is a small super-Earth with a minimum mass of 2.5 Earth masses. It orbits very close to its star, at a distance of only 0.029 astronomical unit, i.e. about 34 times less than the Earth-Sun distance.
GJ 3998 c is the outermost of the two planets. It is a larger super-Earth, or a small Neptune-like planet, with a minimum mass of 6.3 Earth masses. It orbits about 3 times farther than GJ 3998 b, at about 0.089 astronomical unit of its star.
The post GJ 3998 appeared first on NCCR PlanetS.