Kepler-351 is a planetary system made of at least one star and three planets.
The star is slightly smaller than the Sun (0.85 solar radii and 0.89 solar masses) but has a similar temperature (5370 °C, while the Sun’s is 5500 °C). It contains about 25% less metals (elements heavier than hydrogen and helium) than the Sun.
The three planets were discovered thanks to the Kepler space telescope (transits). Kepler-351 b and c, the inner two planets, were announced in 2014 while Kepler-351 d, the outermost planet, was announced in 2016. The masses of the planets are not known but all have radii about two and a half times larger than the Earth, so they are probably small Neptune-type planets. Compared to most known planets, they orbit quite far from their star since their orbital periods (their “years”) are 37, 57 and 142 days (to be compared to Mercury, whose year is 88 days, and the “hot Jupiters”, whose year is only a few Earth-day long).