Capella is not one star but a system of four stars. The primary star, Capella Aa, is 12 times the size of the sun and has nearly three times the mass. Capella Ab is nine times the size of the sun and has slightly less mass than Capella Aa.
The Capellan system also has two red dwarf stars: Capella H and Capella L. Capella H has a little more than half the mass of the sun, while Capella L has about 0.19 the mass of the sun. Capella H is a little more than half the size of the sun, while the size of Capella L is unknown as of 2014.Learn More
While Capella appears to be a single star, it is actually a group of four stars that make up the sixth-brightest object in the night sky. The two stars that make up the brightest part of Capella have a surface temperature comparable to the Sun, about 4,900 degrees Kelvin.Full Answer >
Depending on the star's size, a supernova explosion can leave behind a neutron star, also known as a pulsar, or a black hole. A pulsar is an extremely dense ball of neutrons 10 to 20 miles in diameter that can rotate over 700 times per second. A black hole forms when a supernova remnant is so massive that no force of nature can stop its collapse.Full Answer >
The reason that stars swell in size after exhausting their hydrogen cores is that the stars begin fusing helium, according to the University of Michigan. The helium releases more energy during fusion than the hydrogen releases during the process. The amount of energy produced by the helium is greater than that needed to stave off gravitational collapse, which causes the star to swell greatly in size.Full Answer >
A dying star is a called a "red giant." This is a star whose diameter is many times greater than that of the sun (despite the fact that it is cooler). The brightness of a red giant comes from its shell, which is still burning hydrogen.Full Answer >