Kappa Coronae Borealis


Kappa Coronae Borealis, Latinized from κ Coronae Borealis, is a star approximately 98 light years away in the constellation of Corona Borealis. The apparent magnitude is +4.82 and the absolute magnitude is +2.35. It is an orange K-type subgiant star of spectral type K1IV, meaning it has nearly completely exhausted its hydrogen supply in its core. It is 1.32 times as massive as the Sun yet has brightened to 11.6 times its luminosity. Around 2.5 billion years old, it was formerly an A-type main sequence star.

Dust disk

In March 2013, it was announced that resolved images of at least one dust disk surrounding Kappa Coronae Borealis were captured, making it the first subgiant to host such circumstellar belt. The disk extends out to 120 AU.

Planetary system

In October 2007, a giant planet was found by Johnson et al., who used the radial velocity method. In 2012 it was confirmed.
This planet was assumed to be outside the habitable zone on the assumption that the star is K1IVa. Given the star's luminosity, the planet is more likely on the zone's inner edge.
The width of the circumstellar belt suggests the presence of a second planetary companion of the star, either within it or between two narrower belts.