Star Cycle - Physics

nebula - protostar

a cloud of dust and gas. Gravity pulls it together to form a protostar, and temperature and pressure is increasing.

protostar - main sequence star

Temperature and pressure continue to increase, and hydrogen is fusing into helium.

main sequence star

it enters a long stable period when gravitational attraction pulling everything in is in equilibrium with radiation pressure from fusion. The larger the mass, the shorter its time as a main sequence star.

main sequence star - red giant

Hydrogen runs out, causing the core to collapse. The outer layers swell and cool, turning red.

red giant - white dwarf

When the star runs out of helium to fuse into carbon and other lighter elements, fusion no longer supports the star, and the red giant collapses, heating up as it shrinks.

white dwarf - black dwarf

White dwarf radiates its heat out to the universe, cooling down.

main sequence star - red supergiant

star has much greater mass. Hydrogen runs out, causing the core to collapse. The outer layers swell and cool, turning red. Collapsed core increases pressure and temperature so helium can fuse into elements up to and including iron.

red supergiant - supernova

When light fusion stops, the star collapses in on itself. The temperature and pressure increases to such a degree that the collapse suddenly reverses in a huge explosion.

supernova - neutron star or black hole

In a supernova, there is so much energy that elements heavier than iron are fused. Outer layers thrown into space pushing the core even more tightly inwards, causing atoms to collapse in on themselves. The remnants are known as a neutron star. All the protons and elevators combine to form solid object poorly made of neutrons. If star is massive enough, it will collapse to an infinitely small point, forming a black hole, a super dense region of space that light can not escape from

color of stars from hot to cold

blue, white, yellow, orange, red. the hotter the star the more light of higher frequencies it will emit.

size and brightness of star

the bigger and hotter the star the brighter it is

distance and brightness

the closer the star the brighter it appears

absolute magnitude

how bright a star would be if it was at a fixed distance from earth (around 3.1 × 10^17). This allows us to compare stars brightness without it being skewed by distance

absolute magnitude and brightness

the lower the absolute magnitude, the brighter the star.