ASTR 152 Lecture Notes - Lecture 11: Milky Way, List Of Largest Galaxies, Parsec
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P, it has been determined, has a period of 1 100 days. A longer period means a lower absolute magnitude: these (cid:448)aria(cid:271)le stars are used as (cid:862)distance indicators(cid:863) or (cid:862)standard candles(cid:863, we found the andromeda galaxy by using variable stars. Our cluster is a very poor one; belongs to a cluster called the (cid:862)lo(cid:272)al group(cid:863) (cid:862)lo(cid:272)al group(cid:863) has only 30-40 galaxies; 3 spirals, 4 irregulars, and the rest are dwarf ellipticals. If two galaxies of very different sizes merge, it is called (cid:862)gala(cid:272)ti(cid:272) ca(cid:374)(cid:374)i(cid:271)alis(cid:373)(cid:863) Determining distance from galaxies: standard candle formula (uses magnitude-distance formula, the hu(cid:271)(cid:271)le la(cid:449) (cid:894)(cid:862)the la(cid:449) of redshifts(cid:863)(cid:895) This is just redshift/blueshift and the doppler effect converted into radial velocities. Hubble also noticed more distant galaxies had a larger redshift than closer galaxies. Eventually hubble introduced a relationship for galaxies between their distances and their redshift/radial velocity (the hubble law)
