Have you ever seen a star shine so bright and be so much bigger than the
rest? I'm not talking about the North star, I'm talking about Betelgeuse.
Betelgeuse is found on the shoulder of Orion's belt, and is the largest
star in our galaxy. When Betelgeuse was in the main sequence (the stage
at which stars spend most of their lives) it was probably 30 times more
massive than it is now.
Betelgeuse is 1000 times larger than our sun, 50,000 times more luminous
(visible), 600 times the diameter, but only 20 times more massive.
Betelgeuse has already lost a large amount of its mass. Betelgeuse is so
large that the outer layer is barley held together by gravity. In the 1830's
there was a tremendous outburst during which Betelgeuse became an object
that you could see with the naked eye. It let loose a large amount of gas
with a mass equal to the mass of our sun.
Betelgeuse is often referred to as an enormous "boiling ball" of gas heated
by the release of energy from its core (convection). Ultra violent wave
lengths showed that the star's atmosphere contains very hot gas about twice
the surface temperature. This star's atmosphere also contains lower-temperature
gas that is found near the surface of the star. Large amounts of dust and
gas are also expelled from this red super giant star.
Betelgeuse is about 20 times more massive than our sun. In 1836, Sir John
Herschele noticed that Betelgeuse was changing its brightness. This was
caused by the star's change in size over an approximate 6 year cycle. If
Betelgeuse were to extend into the Asteroid belt (which it is very close
to doing) it would swallow Mercury, Venus, Earth, and Mars.
Betelgeuse is a red star, a super giant star. Red stars are cool stars.
The brighter the star, the cooler it is. The bluer the star, the hotter
it is and the more gravity in its atmosphere. The amount of gravity it
has also has to do with the size and mass of the star, but not all stars
are colored. Some stars are so small that they do not have a color. But
not all stars are like that. The star Mira is also a super giant star but
it has no color. It is almost as big as the star Betelgeuse but it has
no specific color.
Stars come in all different colors, shapes and sizes. Not all stars are
the same. Not all stars are view able from the earth. You need some kind
of telescope to see them. Stars come in every shape and size and not all
of them are round. There are some octagonal shaped stars.
stars are a very beautiful thing, if you actually take the time to look
at them closely. Who knows, you may even be able see to Betelgeuse.
http://obsreve.ivv.nasa.gov/nasa/space/stellardeath/stellardeath_1count2.html
http://www.aoc.nrao.edu/pr/betel.html
http://earthsky.com/2000/es000127.html
http://observe.ivv.nasa.gov/nasa/space/stellardeath/ste