White Dwarf :-
Stars like sun becomes white dwarf when they exhausts their nuclear fuel.
Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula. Only the hot core of the star remains. This core becomes a very hot white dwarf, with a temperature exceeding 100,000 Kelvin. A teaspoonful of their matter would weigh as much on Earth as an elephant—5.5 tons. White dwarfs typically have a radius just .01 times that of our own sun, but their mass is about the same.Fusion in a star's core produces heat and outward pressure, but this pressure is kept in balance by the inward push of gravity generated by a star's mass. When the hydrogen used as fuel vanishes, and fusion slows, gravity causes the star to collapse in on itself.
Since our Sun won't be hot enough to ignite the carbon it its core, it will succumb to gravity again. When the core of the star contracts, it will cause a release of energy that makes the envelope of the star expand. Now the star has become an even bigger giant than before! Our Sun's radius will become larger than Earth's orbit!
The Sun will not be very stable at this point and will lose mass. This continues until the star finally blows its outer layers off. The core of the star, however, remains intact, and becomes a white dwarf. The white dwarf will be surrounded by an expanding shell of gas in an object known as a planetary nebula. They are called this because early observers thought they looked like the planets Uranus and Neptune. There are some planetary nebulae that can be viewed through a backyard telescope. In about half of them, the central white dwarf can be seen using a moderate sized telescope.
 |
| Add caption |
Since our Sun won't be hot enough to ignite the carbon it its core, it will succumb to gravity again. When the core of the star contracts, it will cause a release of energy that makes the envelope of the star expand. Now the star has become an even bigger giant than before! Our Sun's radius will become larger than Earth's orbit!The Sun will not be very stable at this point and will lose mass. This continues until the star finally blows its outer layers off. The core of the star, however, remains intact, and becomes a white dwarf. The white dwarf will be surrounded by an expanding shell of gas in an object known as a planetary nebula. They are called this because early observers thought they looked like the planets Uranus and Neptune. There are some planetary nebulae that can be viewed through a backyard telescope. In about half of them, the central white dwarf can be seen using a moderate sized telescope.
0 Comments