Stellar Physics Flashcards
What is the symbol and units of luminosity?
L
( J/s or watts)
What is b the symbol of?
Apparent brightness
How are stars formed?
They’re formed in interstellar clouds when gravitational forces overcome thermal pressure and cause a molecular cloud to contract until the core becomes hot enough to sustain nuclear fusion, which then provides a thermal pressure that balanced the gravitational force
What do the proton-proton chains in stellar fusion reactions do?
Convert hydrogen to helium
How do stars maintain their outward thermal pressure to balance inwards gravitational forces?
Hydrogen fusion in the core of a star supplies energy to balance forces
What happens when the hydrogen in the core of a star becomes depleted?
Nuclear fusion in the core ceases and gravitational forces cause both the core and the shell (still containing hydrogen) surrounding the core to shrink.
In a star like the sun what happens when the hydrogen shell around the stars core becomes hot enough for hydrogen fusion?
Hydrogen fusion leads to an increase in pressure which pushed the surface f the star outwards causing it to cool -> at this stage the star will be a giant or supergiant.
When does a star such as the sun become hot enough for helium in the core to begin fusion?
When the core shrinks
What determines the lifetime of a star?
The mass of the star
Ultimately what does every star become?
A white dwarf, a neuron star or a black hole. The mass if a star determines its eventual fate
