forstjarna

Forstjarna, also known as the Northern Crown, is a constellation located in the Northern Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy and remains one of the 88 modern constellations recognized by the International Astronomical Union. The constellation is relatively small, covering an area of 194 square degrees, and is positioned between the larger constellations of Hercules and Boötes.

Forstjarna is notable for containing the star Alphecca, also known as Alpha Coronae Borealis, which is a binary star system. The primary star, Alphecca A, is a white main-sequence star, while the secondary star, Alphecca B, is a red dwarf. The constellation also includes the variable star T Coronae Borealis, which is a recurrent nova that has erupted several times in the past, most recently in 1946.

The constellation's name, Forstjarna, is derived from the Old Norse words "forn" meaning "ancient" and "stjarna" meaning "star," reflecting its historical significance in Norse astronomy. The constellation is visible from latitudes between +90° and -40°, making it a prominent feature in the night sky of the Northern Hemisphere during the summer months.