Accretion Disk Density & Fusion: What You Need to Know

[discord73]

Can an accretion disk get dense enough to start fusion? How dense does something have to be in order to start fusion?

Does it depend on the material?

is there a way of measuring the density of accretion disks?

 

[Chronos]

It takes about 100 Jupiter masses to trigger hydrogen fusion. This is the lower limit for a brown dwarf star. Small is not bad, though, such a star can burn steadily for 100 billion years.

 

[wil3]

Yes, but the accretion disk will not form a disk-shaped star- it will fail to reach a stable equilibrium, like stars do, and instead just burn off super fast. This event is known as a nova.

If the accretion disk gets massive enough that a white dwarf passes the Chandrasekhar limit, carbon fusion occurs and the event is known as a Type 1A supernova.