Corona Borealis

Corona Borealis /kɵˈroʊnə bɒriˈælɨs/ is a small constellation in the northern sky. Its name is Latin for "northern crown", a name inspired by its shape; its main stars form a semicircular arc. One of the 48 constellations listed by the 2nd century astronomer Ptolemy, it remains one of the 88 modern constellations. The brightest star is the 2.2-magnitude Alpha Coronae Borealis. Four star systems have been found to have exoplanets to date; three of these are orange giants, while the fourth—Rho Coronae Borealis—is a solar twin, very like our own Sun. Abell 2065 is a highly concentrated galaxy cluster located one billion light-years from our Solar System containing over 400 members, the brightest of which are 16th magnitude. ... Corona Borealis is a small constellation bordered by Bootes to the north and west, Serpens Caput to the south, and Hercules to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'CrB'. ... Stars. Johann Bayer gave twenty stars in Corona Borealis Bayer designations from Alpha to Upsilon in his 1603 star atlas Uranometria. The components of the double star Zeta have since been designated Zeta1 and Zeta2, and John Flamsteed equated his 20 and 21 Coronae Borealis with Nu1 and Nu2. The seven stars that make up the constellation's figure are all 4th-magnitude stars, except for the constellation's brightest star, Alpha Coronae Borealis. This blue-white main-sequence star, also called Alphekka and Gemma, is of magnitude 2.2, though it is an Algol-type eclipsing binary. It varies by 0.1 magnitudes with a period of 17.4 days. Alphekka is 75 light-years from Earth. The other six stars are Theta, Beta, Gamma, Delta, Epsilon, and Iota Coronae Borealis. ... Deep sky objects. Corona Borealis contains no bright deep-sky objects. Abell 2065 is a highly concentrated galaxy cluster containing over 400 members, the brightest of which are 16th magnitude. The cluster is more than one billion light-years from Earth. Another galaxy cluster in the constellation, RX J1532.9+3021, is located approximately 3.9 billion light years from Earth. At the cluster's center is a large elliptical galaxy containing the supermassive black hole. In November 2013 astronomers discovered the largest structure in the universe ever found—the Hercules–Corona Borealis Great Wall, which lies partly within this constellation's borders. [Corona Borealis. Wikipedia]