PCS 181 Lecture Notes - Lecture 4: Parsec, Accretion Disk, Angular Diameter
6 Oct 2015
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Document Summary
The milky way is estimated to have a luminosity of l(mw) -> 1 x 10^11 l(o) M(mw) -> (1 x 10^11) (1. 99 x 10^30 kg) = 2 x 10^41 kg on calculator use it as 1. 99 x 30. Galaxy masses range from 1 x 10^5 m(o) to 1 x 10^13 m(o). Our galaxy, the milky way, has a mass of 5. 8 x 10^11 m(o). Spirals spin faster than ellipticals -> higher angular momentum, l = mvr. (mass, velocity, radius) Spirals form/contract slowly and have gas/dust to support ongoing star birth. Spiral structure is extremely delicate and would be destroyed in a collision. Obvious spirals have not undergone major collisions. Ellipticals contracted faster and triggered early star formation that used up their dust and gas. Galactic cannibalism: mergers of galaxies produce a giant elliptical at the center of a group of galaxies. 1960 spectra were obtained for two blue star-like objects: 3c48 and 3c273. Their spectral lines could not be identified.
