Star Lifecycle

Star Lifecycle

A black dwarf is the stage after a white dwarf. It takes so long for stars to get to this stage that none has probably ever gotten to this stage. Our universe is so young and it will take a few times older than our universe even is for any sun to turn into a black dwarf. Our nearest star, Proxima Centauri is a red dwarf and scientists believe that it will take billions of years for it to end it's life cycle and eventually become a white dwarf and then a black dwarf. Black dwarfs are stars that are burnt out and do not have any light or heat anymore. Our Sun will probably become a black dwarf too someday.

A white dwarf only has the radius of 0.02 of the Sun and it's true brightness is 0.005 of the Sun. It's surface temperature is 45,000 degrees Fahrenheit or 25,000 degrees Celsius.  A white dwarf is not really white, its color depends on its temperature, and it can be from violet to deep red. A white dwarf can not be seen without a telescope. Did you know a teaspoon full of white dwarf would way 5 tonnes? A white dwarf is one of the last stages of a star from when the giant star releases its outer layers of gases and leaves the center or core of the star. The white dwarf is then only about the size of the Earth but still has 3/4 the mass of our Sun. 

A brown dwarf is when a star was being created but it didn't get enough mass to become a real star. It is a bit bigger than Jupiter or a white dwarf but smaller than our sun, but they actually have about 13 to 75 times Jupiter's mass. It has a radius of 0.1 of the Sun and has a true brightness of 0.00001 of the Sun. It's surface temperature is 1,300 degrees Fahrenheit or 720 degrees Celsius. Instead of staying the same size or expanding it will shrink and cool down and fade. The brightest brown dwarf sometimes resembles a red dwarf.

A red dwarf's radius is half of our Sun's radius and its true brightness is 0.05 of the Sun. A red dwarf is a low mass star, and since small stars take very long to slowly burn up there fuel they last a very very long time. A red dwarf can live for more than 10 times the present age of our universe, around 200 billion years at its regular rate. It's surface temperature is 6,000 degrees Fahrenheit or 3,300 degrees Celsius. Red dwarfs are the most popular type of sun and  make up just over half of all the stars in our entire galaxy! If our Sun was a red dwarf, from earth it wouldn't provide us with daylight it would only give us light like when our sun is rising or setting. Our nearest neighbour star Proxima Centauri is a red dwarf and it can't be seen in the sky because red dwarfs are usually not bright enough to be seen without a telescope. It is part of a triple star system.

A yellow dwarf is a star like our Sun. A yellow star lives around 10 billion years. Eventually a yellow star will bloat into a red giant and it's outer layer will shoot out into space leaving a white dwarf and then later a black dwarf. A yellow's sun's radius and true brightness is 1 of our Sun. Its surface temperature is 10,000 degrees Fahrenheit or 5,500 degrees Celsius. For more information about yellow stars you can look at the section called All About Our Sun.

A blue giant's radius is 10 Suns and its true brightness is 800,000 suns. Its surface temperature is 80,000 degrees Fahrenheit or 45,000 degrees Celsius. A blue giant is a star that was born a giant and later in its life cycle just like a yellow star it will bloat into a bigger star but instead of turning into a red giant it turns into a red supergiant. A blue giant usually lives a pretty short life. 

A red giant's radius is hundreds of times larger than the Sun and its surface temperature is relatively low. The surface temperature is around 8,540 degrees Fahrenheit or 4,727 degrees Celsius. A red giant is a star that increase in temperature and implodes and the heat energy it releases causes it to expand. A red giant is a star like our Sun after it expands and cools down and gets a bit dimmer. Once our Sun becomes a red giant it will turn all of our inner planets into cinder. 

A blue supergiant is an expanded blue giant. They have a surface temperature of 36,000 to 90,000 Fahrenheit or 20,000 to 50,000 degrees Celsius. There radius can be up to 25 of our Sun. They are rare and some of the brightest stars in the universe. As the blue supergiant's core reaction speeds up and slows down and the wind changes can change back and forth from a blue supergiant and a red supergiant. A blue supergiant has fast but rare wind compared to a red supergiant which has a slow wind. Blue supergiants are rarely found with older stars they are found with young stars.

A red supergiant has a radius of 500 Suns and a true brightness of 40,000 Suns. It has a surface temperature of 6,100 degrees Fahrenheit or 3,400 degrees Celsius. They are the biggest in size but not in mass or surface temperature or true brightness in the known universe. A red supergiant ends its life it in a super nova. A red supergiant is a star that is in its last phase of its life burning helium. A red supergiant is just a bigger version of a red giant. Red supergiants have no photosphere.

Source: http://www.odec.ca/projects/2008/lafl8s2/Whatdifferenttypesofstarsarethere.html