1.6 - Stellar physics Flashcards
Where are stars formed?
in interstellar clouds
create a simple hertzsprung-russel diagram
diagram should include:
main sequence, giant, super giant, white dwarf.
axis: wavelength, luminosity, temperature 3000K - 30,000K
how are stars formed?
gravitational forces overcome thermal pressure and cause a molecular cloud to contract until the core becomes hot enough to sustain nuclear fusion, which provides a thermal pressure that balances the gravitational force.
give an example of a p-p chain
see jotter
what area of the H-R diagram contains stars which fuse hydrogen in their cores?
the main sequence
what are the 3 ultimate fates of a star
a white dwarf, a neutron star or a black hole
describe the process of a star becoming a red giant
once the hydrogen in the suns core has been completely fused into helium, the core shrinks due to a decrease in thermal pressure, if the heat energy is great enough in the core the helium will fuse together, hydrogen in the shell of the star begins fusion, increasing the thermal pressure, causing the stars shell to expand and cool.
how does a star stay a relatively constant size
hydrogen fusion in the core of a star supplies outward thermal pressure which balances inward gravitational forces.
in a star like the sun what is possible in the shell
hydrogen fusion
what happens in a star like the sun to allow fusion of helium to occur
the core shrinks becoming hotter
what determines the lifetime of a star
its mass
