Stars Flashcards
(14 cards)
Wien’s Displacement Law
T (Kelvin) is inversely proportional to the peak wavelength
Star Birth
(Formation of a Star)
Nebulae form as tiny gravitational attraction between particles of dust and gas pulls particles towards each other forming gas clouds.
As they get closer gravitational collapse accelerates.
Eventually a proto-star is formed.
To become a star the proto-star must undergo nuclear fusion.
The object must be very hot and large to overcome the electrostatic repulsion and create He atoms from H atoms.
Proto-star
A hot very dense sphere of dust and gas.
Star Life
Star is in stable equilibrium with constant size.
Gravitational forces act to compress the star but radiation (photons) and gas (nuclei) pressure push outwards balancing the forces.
Stable Phase: Main Sequence
Massive Stars are stable for?
A few million years
Smaller Stars are stable for?
A few billion years
Planets
An object in orbit around a star with:
a mass large enough for its own gravity to give it a round shape.
no fusion reactions
cleared its orbit of other objects.
Planetary Satellite
A body in orbit around a satellite.
E.g. moons, man-made satellites
Comets
Small irregular shaped bodies made up of ice, dust and small pieces of rock.
Solar System
Contains the sun and all the objects that orbit around it.
Galaxy
A collection of stars, interstellar dust and gas.
Life Cycle (Low Mass Stars)
Cooler than massive stars
Remain on main sequence much longer
After billions of years, they run low on H2 fuel and move onto the next stage in their life.
Red Giants (Low Mass Stars)
Mass: 0.5M and 10M
Gravitational Pressure > Reduced pressure from gas and radiation pressure.
Core starts to collapse
Pressure increases enough to have fusion in a shell around the core.
