AST 111 Chapter Notes - Chapter 1: Hubble Ultra-Deep Field, Barred Spiral Galaxy, Hubble Space Telescope
6 Jun 2020
School
Department
Course
Professor
Document Summary
1 million second exposure with the hubble space telescope the deepest image of the cosmos ever taken. Stars of all ages, many gas clouds. Spheroidal component bulge and halo, old stars and few gas clouds. Blue white colour indicates ongoing star formation. Red yellow colour indicates older star population. Barred spiral galaxy has a bar of stars across the bulge. Lenticular galaxy has a disk like a spiral galaxy but much less dusty gas (intermediate between spiral and elliptical) Elliptical galaxy: all spheroidal component, virtually no disk component. Our milky way galaxy is a spiral galaxy like this. Apparent brightness of star cluster"s main sequence tells us its distance. Because the period of cepheid variable star tells us its luminosity, we can use these stars as standard candles. Cepheid variable stars with longer periods have greater luminosities. Modern telescopes can observe galaxies out to billions of light years. They are looking back in time to the distant past.
