ASTRON final exam Questions and answers, VERIFIED.

ASTRON final exam Questions and answers, VERIFIED. Ch 17- What do we use medthods of stand candles? - -Astronomers cannot use parallax to measure vast distances because the angle by which the galaxy's position changes as we move around the sun is too tiny to be detected, so astronomers must use this method to find distance How do we use standard candles? - -if we know the luminosity we can use the inverse-square law to deduce its distance from how bright it looks to us Cepheids - -are more luminous than the sun and are often used as a class of luminous for finding standard candles like in hmwk 9 problem 1 According to the inverse-square law, if two objects have the same luminosity, their apparent brightnesses (in the milky way and the distant galaxy) are related to their ____ and _____ (p451). - - distiance (to cepheid in Milky Way) and distance to Cepheid in distanct galaxy) In a nearby galaxy we see an identical Cepheid variable star that appears to be 1e+11 times dimmer. Use the standard candle method to determine the distance to the nearby galaxy (if distance is 350ly) - - distance in Milky Way = 1e+11 (we think it appears to be) __________________ The other Star Galxy red shifts are not Doppler shifts they are a result from - -the expansion of the universe (further described in chapter 18) The puzzle of red shifts led Hubble to find that the red shift was larger for dimmer galaxies which means that the speed or the ___ ___ increases with ____ - -its recession velocity increases with distance (the faster a galaxy recesses the farther away it is), brightness falls like luminosity squared What the Hubble formula? - -V=Hd