Download When Stars Blow Up

When Stars Blow Up
What Stars Explode?
•Cataclysmic variables
•Novae
•Supernovae
Cataclysmic Variables
•Binary star systems incorporating a white dwarf
•Outbursts due to disk instabilities
GK Per = Nova Per 1901
Novae
Thermonuclear detonations on a white dwarf
•Hydrogen accumulates, mainly from accretion in a CV
•At the base of the accreted layer, electrons become
degenerate
•When the temperature reaches a few MK, fusion begins
•Degenerate fusion is a runaway.
•All the H fuses to He and heavier elements in a soundcrossing time (a few minutes)
•The star increases in brightness ~ 10,000 times
•Most of the matter is ejected
Supernovae
Supernova
Collapse of a massive stellar core
•Type Ia: core collapse of a 1.4 M white dwarf
o complete detonation of the core - no remnant
•Type II: core collapse of a star with M > 8M
o yields a neutron star or black hole
o core collapses when fuel all used up and gravity wins
Will the Sun Explode?
No!
•The sun is not a white dwarf
•The sun is not in a binary system
•The sun is not a high mass star
The Fate of
the Sun
•Brightens on main sequence
•Red Giant
•Planetary nebula + WD