Dark Energy/Dark Matter
Quantum effects when the universe was small lead to irregularties in the distribution of matter and energy in the cosmos. These irregularities, through gravitational interaction amongst themselves, coalesce into galaxies.
Have the most star formation.
Oldest galaxies, usually the result of collisions between spiral/bar galaxies.
Most of the matter in a galaxy is invisible to our instruments, only detectable by its influence.
Fusion, gravitational force of star’s mass overcome electromagnetic force of star’s electrons, forcing atomic nuclei together, fusing them.Main Sequence
O, B, A, F, G, K, M, going from largest to smallest, and hottest to coolest.
O = ultraviolet, burn hydrogen very quickly, strong He, Si, O, N, C lines. 1/3,000,000, millions of times more powerful than sun.
B = blue, He, H, Mg, Si lines, 1/800
A = white, strong H lines, Fe, Mg, Si, Ca lines, 1/160, common in night sky
F = white/yellow, H and ionized metal lines (Ca). 1/33
G = yellow, like our sun. weak H lines, strong Ca lines. 1/16.
K = orange, almost no hydrogen, mostly metals. 1/8. Giants-dwarves.
M = red, no hydrogen. Most common main sequence stars. Red Giants.Giants
Towards the end of their lives, stars will have burned most of their hydrogen and they will begin to collapse. At a certain pressure and temperature, the star will begin to fuse Helium, thus preventing further collapse. Helium only provides about a tenth of the energy of normal
Supernova/Hypernova - multiple types:
Type 1a: A white dwarf that accretes enough matter onto its surface that it exceeds the Chandrasekhar limit, or about 1.38 solar masses, and the white dwarf starts to collapse. This ignites carbon fusion in the white dwarf, which releases large amounts of energy, and it increases the luminosity of the white dwarf by a factor of billions.
Type 1b: Large stars that have shed most of their outer layers of hydrogen and their cores collapse, producing a supernova.
Type 1c: Same as 1b, except that it doesn’t show helium spectra either.
Type II: Traditional supernova. Large star, generally above 8 solar masses, finally runs out of fusion fuel, and its core catastrophically collapses into a neutron star or a black hole. This collapse stops very suddenly when the neutron star forms, causing massive rebound and supernova.
Pair-Instability: 130 solar masses to 250 solar masses, the gamma rays produced by the star are so energetic that when they interact with nuclei, they condense into a positron and an electron. This reduces the expansionary pressure, which causes the outer layers of the star to collapse, which makes even more energetic gamma rays, which results in more pair production, and the cycle continues until the entire star is blown apart, leaving nothing left.
Accretion of the Gas Disk around a star.
Types of planets
silicon, oxygen, iron/nickel.
hydrogen, helium, water, ammonia, hydocarbons
Death of Stars
Black DwarvesBlack holes
End of the Universe.