How does a star become a white dwarf?
The exact process of a star becoming a white dwarf depends on the mass of the star, but all stars less massive than about 8 times the mass of the Sun (99% of all stars) will eventually become white dwarfs. Normal stars fuse hydrogen into helium until the hydrogen deep in the center begins to run out. For very massive stars this may take only a million years – but for stars like the Sun the hydrogen lasts for 10,000 million years. When enough helium is produced from fusion, it begins to sink to the middle of the star and release some heat in the process. This messes up the internal balance of the star, and it begins to bloat into a red giant. If the star is massive enough, it may eventually get hot enough in the center to fuse the helium into carbon and oxygen. The star then enjoys another relatively stable period, though much shorter this time. The carbon and oxygen, in their turn, sink to the middle. If the star isn’t massive enough to reach the temperature needed to burn carbon and o
