Is a white dwarf before or after a supernova?

Question

I am doing this science project, and I am trying to figure out that. So, someone please help me with this question. Thanks :]

why is it neither???

Answer 1

In one sense neither, and in another before.

It comes neither before nor after a supernova in most cases. White dwarfs are believed to be formed by old, but not very massive stars (like our Sun...), at the end of their active lifetime. At this point, with the specifics depending on the details of the star's size and past history, the outer layers of the star just kind of "puff" out (this is not an explosive event, it takes place over a long period of time [for us, not the star]). The result is that the core of the star is left sitting there, supported by quantum mechanical effects (the particular effect is called electron degeneracy pressure). This core is a white dwarf, and it in many if not most cases just sits around cooling off for several billion or trillion years. No supernova occured in its formation, and no supernova will necessarily happen after any amount of time.

This isn't to say that a white dwarf has nothing to do with supernovae. In particular, what is known as a Type Ia supernova (an important class in astronomy) is thought to be the result of a white dwarf exploding. What happens here is that if, say, a white dwarf has a companion star or other source of lots of mass near it, and it begins to pull this extra mass into itself. Now a white dwarf is mostly carbon and oxygen which was burned up in nuclear fusion because the star it had been a part of wasn't big enough to create the pressures and temperatures necessary to do so. But now, with this extra mass, eventually it does reach a point where it can burn carbon. The result is the astrophysical analogy of a spark in a room filled with gas and dry paper. The carbon gets burned very quickly, so quick that the process is explosive, and the white dwarf is more or less destroyed. This is a Type Ia supernova.

It's worth pointing out that not all white dwarves do this. It depends upon having a nearby source of mass to pull into it (enough so that you could make several thousand Earths of it). This is a chance arrangement, though not a hugely uncommon one. So some white dwarves will never become type Ia supernovae, and some will, depending upon circumstances.

Answer 2

A white dwarf will not go supernova under normal circumstances. The dwarf state is what happens to a small to medium sized star after first swelling into a red giant, then collapsing under it's own mass. These stars don't have sufficient mass to go supernova. On rare occasions, white dwarfs can generate an explosion (called a type Ia supernova), but such events are infrequent. They only occur in the milky way once every 1000 years or so, and considering the size of our galaxy (100,000 light years across), the odds of one happening near us any time soon aren't very high. Those who are saying that white dwarfs never go supernova are incorrect, though. A large, giant, or hyper-giant star does contain enough mass to generate a supernova explosion, however, such an event would only be harmful to the earth if one of the star's poles was facing towards us. Even a relatively close-by star wouldn't harm us, so long as its poles weren't directed at us. Sirius B won't go supernova. It burnt itself out long ago, and is currently in a white dwarf state, destined to cool off over many billions of years, first becoming a brown dwarf, and then a black dwarf. A near-earth supernova (less than 100 light years away) could deplete the ozone layer, exposing the surface to solar and cosmic radiation. Both sides of the earth would be equally affected, since it rotates (the gamma rays wouldn't pass by in a matter of minutes, the earth would be exposed to them for years), and the reactions within the ozone layer would affect the whole planet even if we were stationary. Some have theorized that a nearby supernova was the cause of at least one of the mass extinction events in earth's history. However, such an event is unlikely to occur anytime soon, so I wouldn't worry about it.

Answer 3

Before.
Although white dwarfs are not the remnants of a super nova like neutron stars or black holes it is thought that white dwarfs can explode as Type I super novas.
White dwarfs are the dead corpse of a small star like the sun. Their formation is not preceded by a supernova.

Stars at least 8 times more massive than the sun do die in a supernova. These are called Type II supernovae.

A white dwarf that is near 1.44 times as massive, or the Chandrasekhar limit, is on the verge of collapsing on itself. It the star had been just a little more massive it would have. But here it is juuust help up by the pressure of degenerate electrons. If the white dwarf is part of a binary star system eventually the other star will also become a giant star. When it does it can pass matter onto the white dwarf. It is pushed over the limit and all of it undergoes fusion and explodes in a Type I supernova.

Answer 4

Neither . If our sun had a companion star, and our sun turned into a white dwarf,it can strip off hydrogen from the companion star. When there is enough hydrogen on the surface of the white dwarf, there will be an explosion, like a hydrogen bomb. The white dwarf will go nova. As long as there is a companion that will supply hydrogen to the white dwarf, there can be repeated novas from the same white dwarf.

Answer 5

Neither..! A white dwarf is the end result of a star like our sun that has exhausted all its nuclear fuel, temporarily expanded into a red giant phase, then diminished down to a white dwarf star. The end result of a supernova is either a neutron star or a black hole.

Answer 6

Neither

Answer 7

after.

Answer 8

neither