Dwarf questions

[Bufferz]

What happens to a white dwarf after it becomes one? I mean, once its a WD, it runs on the remaining material reactions within its remaining material, but when that runs out, does it just disappear into nothing, or just become another rocky piece of debris, and also, assuming the Earth, Mars, etc survive the Red Giant phase, would they still orbit the WD, or simply drift off into space since there would be so little mass as to create enough gravity to hold the planets in orbit around the sun?

[lunator]

Hi

In simple terms the white dwarf which is the core of the dying star will slowly cool down and become a 'black dwarf'. A star like the Sun will become a black dwarf eventually and if the earth survives the Red Giant phase (this is an area of debate) it will remain in orbit just futher out as the mass of the 'black Dwarf Sun' will still be significant mass.

Cheers

Ian

[Bufferz]

thanks for the quick reply, Ian, haven't heard of a black dwarf, just whites and browns, but surely Earth would survive as the sun (Gradually, its not going to happen overnight) increases in size, its gravitational pull will reduce and so Earth would have its orbit move outward (although the planet would be burnt to a crisp!)

[lunator]

Hi Phil

there is debate about this at present. It was thought that the earth would survive the Red Giant phase as the mass loss of the Sun would allow the orbit of the earth to increase.

The latest theory is that the earth will caught in the outer layers and this drag will counteract the reduced pull of the Sun's gravity and the earth will be pulled into the Sun.

Nothing is certain but opinion is moving towards a firery end.....

[Paxo]

Hi Phil

The latest theory is that the earth will caught in the outer layers and this drag will counteract the reduced pull of the Sun's gravity and the earth will be pulled into the Sun.

Nothing is certain but opinion is moving towards a firery end.....

There's nothing like a happy ending! :crybaby:

Steve..

[lunator]

Well hopefully the Human race will have moved on since then....

[InvaderXan]

Do you mind if I add a little something to this...?

A white dwarf will eventually cool and turn into a black dwarf, yes. Unless it manages to accrete more matter somehow (say, from a binary companion or a dense molecular cloud). In that scenario, should a white dwarf ever reach 1.4 solar masses it'll explode violently as a type Ia supernova.