ASTRONOMY 162 Test 3 c = 300,000 km/sec v = dH wavelength(max) = 3000/T 1. What important characteristic of certain variable stars (like Cepheids) make them distance indicators? a) They all lie in the same region of the HR diagram b) They are easy to detect because they blink c) They are fairly common * d) Their is a relationship between their period and their luminosity 2. After the first few minutes following the big bang but before galaxies formed, the chemical composition of the universe was a) similar to that of the Sun b) almost entirely neutrons * c) almost entirely hydrogen and helium d) almost entirely hydrogen 3. The rotation of the Milky Way Galaxy can be inferred from the a) apparent magnitudes of type O and A stars * b) the Doppler shift of the 21 cm line of Hydrogen c) the presence of white dwarves in the galactic halo d) x-ray emissions from the galactic center 4. The Milky Way galaxy is most accurately described as * a) spiral in shape b) spherical in shape c) elliptical in shape d) irregular in shape 5. The globular clusters surrounding the Milky Way galaxy a) contain young stars b) are the location of many supernova explosions * c) indicate the shape of the galaxy at an early stage of its formation d) all of the above 6. Hubble's constant refers to a) the fact that the speed of light never changes * b) the rate at which the universe is expanding at the present time c) the average mass-density of the universe d) a number in a formula that will never change its value 7. The expansion of the universe was first observed by a) seeing the 3 degree blackbody radiation * b) Hubble's observations concerning the red shift's of galaxies c) oberving supernovas d) by looking at quasars 8. The relative amount of Hydrogen and Helium in the universe depends on a) the relative number of protons and neutrons in the early universe b) the lifetime of a free neutron c) the rate at which neutrons and protons combine to form deuterium * d) all of the above 9. The 3 degree K blackbody radiation is left over from the time of the universe when its average energy was just below that of a) nuclear fusion in the sun * b) atomic ionization in hydrogen and helium c) galaxy formation d) the energy difference between neutrons and protons 10. The Universe is thought to be about a) 13,000,000 years old b) 1,300,000,000 years old * c) 13,000,000,000 years old d) 13,000,000,000,000 years old 11. A star formed in the earliest stage of the Milky Way's formation a) is usually a red star * b) would have a very small amount of elements heavier than Helium c) never would become a supernova d) would not be still an active star 12. Why is the galactic center invisible to optical telescopes? a) it is too far away * b) there is too much dust between us and the center c) it emits mostly x-rays d) it is moving too fast 13. Suppose Hubble's constant was measured to be twice as large as it is now believed to be. The implied age of the universe would be * a) halved b) the same c) doubled d) none of the above 14. If the density of the universe is greater than the critical density, the universe a) will consist of clusters of galaxies that continually move apart * b) will collapse c) is open d) will continue to expand forever 15. Active star formation occurs in a) irregulars b) spirals * c) both a and b d) neither a or b 16. In general, the greater a galaxy's redshift, the a) smaller it is b) the brighter it is c) fewer the number of stars it contains * d) farther away it is 17. Most Helium nuclei in the Universe formed a) before 1 second after the big band * b) during the first few minutes after the big bang c) in supernova explosions d) in white dwarves 18. Most astronomers believe that the large redshifts of quasars are due to a) their huge mass b) their low temperature c) gravitational effects * d) their extreme distance 19. During the formation of the Solar System, the material which began to condense at the highest temperature was a) hydrogen * b) iron and nickel c) water d) oxygen 20. Why is there currently no star formation in elliptical galaxies? a) they are so massive that gravity prohibits new star formation b) Spiral density waves are needed to form new stars * c) the dust and gas needed to form new stars is not present d) they are too far away for new stars to exist 21. When we study very distant galaxies, we * a) see an object as it was billions of years ago b) find only blue shifted spectral lines c) find that they are all irregular galaxies d) see no evidence of large scale structure 22.The spiral arms of our Galaxy are places where * a) new stars are formed from clouds of dust and gas b) new matter is created out of nothing c) stars begin to spiral into the galactic nucleus d) the oldest stars of the galaxy are concentrated 23. The 3 degree cosmic background radiation is believed to be a) an obvious outgrowth of the steady state theory * b) remnant radiation from the birth of the universe. c) a result predicted by the theory of general relativity d) an aftermath of exploding quasars 24. The location of the "Big Bang" is a) in the direction of the Andromeda galaxy b) at the center of the Milky Way Galaxy * c) everywhere d) none of the above 25. Planets like Jupiter have hydrogen-rich atmospheres like the Sun because they * a) were able to gravitationally attract gas from the solar nebula b) began forming before the Sun c) were able to briefly produce material through nuclear reactions d) ejected heavier materials which then formed the asteroids 26. In the context of extra-terrestial life, how is a technical civilization defined? * a) one that can communicate over interstellar space b) one that has developed interplanetary space travel c) one that can construct tools out of raw material d) one that consists of life-forms that can communicate with each other 27. For how long did life on Earth consist of only single-celled life forms a) 10 million years b) 50 million years * c) 2.5 billion years d) 25 billion years 28. What factor caused different types of planets to be formed (that is, to be made from different types of materials)? a) The rotation of the forming planet b) The quantity of dust particles in the solar nebula * c) The variation in temperature throughout the solar nebula d) all of the above 29. About how many stars are there in the Milky Way? a) one or two million b) 100 million c) 500 million * d) 100 billion 30. How hot was the universe at time zero? a) 10,000 K b) 1,000,000 K c) 100,000,000 K * d) we do not know 31. The Magellanic Clouds are * a) small irregular galaxies that move in orbit around our Milky Way b) regions of active star formation in the Milky Way galaxy c) hazy patches of nebulae which are remnants of supernovas d) clouds of dust at the center of the Milky Way 32. What stars would be unsuitable for development of intelligent life? a) binary stars b) massive, very bright stars (like types O and A) c) white dwarves * d) all of the above 33. Which of the following never changes? a) Planet Earth b) the Milky Way Galaxy c) the universe * d) none of the above