Alpha Coronae Borealis (α CrB, α Coronae Borealis) is a binary star in the constellation Corona Borealis. It is located about 75 light years from the Solar System.
The primary component is a white main sequence star that has a stellar classification of A0V and 2.6 times the mass of the Sun. Estimates of the star's radius range from 2.89 to 3.04 times the radius of the Sun.[2][5] An excess of infrared radiation at 24 μm and 70 μm has been detected about the primary star by the IRAS.[7] This suggests the presence of a large disc of dust and material around Alphecca, prompting speculation of a planetary or proto-planetary system similar to that currently assumed around Vega.
The secondary component is a yellow main sequence star with an estimated stellar class of G5, 0.92 times the Sun's mass and 0.90 times the Sun's radius. The X-ray luminosity of this star is 6 × 1028 erg s-1, which is 30 times greater than the peak activity level of the Sun. This higher activity level is expected for a young star of this class. The corona has a temperature of about 5 MK, which is much hotter than the Sun's corona. The upper limit of 14 km/s for the equatorial rotation velocity is equivalent to a rotation period of 3 days. More likely, the rotation period is 7–9 days.[2][5]
The stars are orbiting about each other in an eccentric orbit one every 17.36 days. Because the plane of this orbit is inclined at an angle of 88.2° to the line of sight to the Earth,[5] the pair form an eclipsing binary system similar to Algol (β Per). The periodic eclipses result in a magnitude variation of +2.21 to +2.32,[8] which is hardly noticeable to the unaided eye.
The space velocity components of this star system are U = +14.257, V = +0.915 and W = +3.147 km/s. α CrB is believed to be a member of the Ursa Major Moving Group of stars that have a common motion through space.[9]
Excerpt from Wikipedia.