• Question: what is a dead star ?

    Asked by to Sarah on 16 Jun 2014. This question was also asked by , .
    • Photo: Sarah Casewell

      Sarah Casewell answered on 16 Jun 2014:

      White dwarfs are dead stars. They are what used to be the core of a star like our sun. Stars are held up against gravity by burning hydrogen into helium. This releases heat which keeps the star inflated. When it runs out of fuel (hydrogen), it can’t keep itself up against gravity and so it collapses in on itself.
      The core is all that is left and they are very dense, and hot – maybe 100 000 degrees! But when they form, they just cool with time.

      Most stars become white dwarfs – they are small – about the size of the Earth and have the entire mass of the sun squeezed into it.
      Any gas that is left over that doesn’t become the white dwarf, is ejected into space and becomes a nebula. Eventually new stars will form here.

Comments