What Is A White Dwarf Star?
A white dwarf is the final stage of the evolution of a star that is between .07 and 1.4 solar masses. White dwarfs are supported by electron degeneracy. They are found to the lower left of the main sequence of the Hertsprun Russel diagram. White dwarf stars got their name because the first to be discovered had a white color. They are characterized by a low luminosity, a mass close to that of our sun, and a radius only that of the earth. These stars are extremely dense because their large mass and small area White Dwarf stars are very dense. Their density is almost 1,000,000 time that of water. White dwarfs also have a low luminosity. This makes it so they have be within a few hundred parsecs away from earth to be observed (1 parsec = 3.26 light years). Facts About White Dwarfs! When a star stops burning the stars with less than 1.4 solar masses shrink greatly in size. While they shrink they start to become very faint. The value of 1.4 solar masses is referred to as the Chandrasekhar li
To astronomers, dwarf is a general term for smaller stars. The color of a star is an indication of the temperature at its surface. Very hot objects emit more blue-white light, while cooler objects emit more red light. Our Sun is termed a yellow dwarf and there are many stars cooler than the Sun called red dwarfs. So a white dwarf is a relatively small star with a very hot surface. In 1844, an astronomer named Friedrich Bessel noticed that Sirius, the brightest star in the sky, appeared to wobble slightly as it moved through space. He inferred that there must be something in orbit around it. Sure enough, in 1862 the faint companion was observed visually by Alvan Clark (a telescope maker) and was given the name “Sirius B”. By the 1920’s, the companion had completed one full orbit of Sirius and its mass was calculated, using Newton’s laws, to be roughly the same as the Sun. When astronomers measured its spectrum, they found that it emitted much more blue light than red, implying that it
