47 Boötis

47 Boötis is a yellow subgiant star located approximately 46 light-years away in the constellation Boötes. It is also known by the Bayer designation d Boötis.

47 Boötis is slightly more massive and luminous than our Sun. Its spectral type is G0IV, indicating that it is evolving off the main sequence and has begun to exhaust the hydrogen fuel in its core. This evolutionary stage signifies that the star is in the process of becoming a red giant.

The star is host to three known extrasolar planets, designated 47 Boötis b, 47 Boötis c, and 47 Boötis d. All three are gas giants, with minimum masses ranging from approximately 0.9 to 3.9 times the mass of Jupiter. 47 Boötis b was one of the first extrasolar planets discovered around a main-sequence star, and its discovery was announced in 1996. The relatively close proximity of the 47 Boötis system to our solar system has made it a popular target for further observation and study to better understand planetary system formation and evolution. The system is considered a benchmark system for testing planet formation theories.