article for September 28, 2020
Article of the day for September 28, 2020 is Rigel . Rigel is a blue supergiant star in the constellation of Orion, approximately 860 light-years (260 pc) from Earth. It is the brightest and most massive component of a star system of at least four stars that appear as a single blue-white point of light to the naked eye. A star of spectral type B8Ia, Rigel is calculated to be anywhere from 61,500 to 363,000 times as luminous as the Sun, and 18 to 24 times as massive. Its radius is over 70 times that of the Sun, and its surface temperature is 12,100 K. Rigel varies slightly in brightness, its apparent magnitude ranging from 0.05 to 0.18. It is classified as an Alpha Cygni variable. It is generally the seventh-brightest star in the night sky and is usually the brightest star in Orion, though it is occasionally outshone by Betelgeuse. With an estimated age of 7 to 9 million years, Rigel has exhausted its core hydrogen fuel, expanded and cooled to become a supergiant. It wil...
