Kepler-23

Kepler-23 is a G-type main-sequence star about 2860 ly away in the northern constellation of Cygnus, the swan. With an apparent visual magnitude of 13.5, it is too faint to be seen with the naked eye. This star is similar in mass and temperature to the Sun, but is larger and more luminous. Kepler-23 is orbited by three known exoplanets.

Planetary system
Three transiting exoplanets orbit this star, discovered using the Kepler space telescope. Two planets, Kepler-23b and Kepler-23c, were discovered in 2011 and were confirmed in 2012. A third planet, Kepler-23d, was confirmed in 2014 as part of a study validating hundreds of Kepler candidates. All three planets are between Earth and Neptune in size (sub-Neptunes), and their masses have been measured via transit-timing variations, showing that they have lower densities than Earth.