ASTR 1504 1514 Astronomy Exploring the Universe Midterm Exam 3 1 A 10 Solar mass star will evolve through the same phases as a 1 Solar mass star A True B False 2 Stars evolve primarily because they run out of fuel in their cores A True B False 3 The more massive a star the more hydrogen it has to burn and the longer its mainsequence lifetime will be A True B False 4 What factor is most important in determining a star s position on the main sequence and subsequent evolution A Temperature B Pressure C Mass D Radius 5 A star like the Sun will eventually become an electron degenerate white dwarf star A True B False 6 What is a planetary nebula A A planet surrounded by a glowing shell of gas B The disk of gas and dust surrounding a young star that will soon form a star system C The ejected envelope of a giant star surrounding the remains of a star D A type of young medium mass star 7 In a white dwarf what is the source of pressure that halts its contraction as it cools A Thermal pressure of the extremely hot gas B Electrons packed so closely that they become incompressible C Neutrons that resist being pressed further together D Carbon nuclei that repulse each other strongly because they each contain six protons 8 A Type Ia supernova occurs when a white dwarf exceeds a mass of A 0 8 Solar Masses B 1 4 Solar Masses C 2 3 Solar Masses D 5 5 Solar Masses 9 Special relativity says that moving clocks run slower A True B False 10 Gravity is nothing more than a curvature in the fabric of spacetime A True B False 11 Gravitational lensing allows us to see distant objects that would otherwise be blocked by a star or galaxy A True B False 12 We can identify only a small fraction of all the pulsars that exist in our galaxy because A gas and dust efficiently block radio photons B few swing their beam of synchrotron emission in our direction C most have evolved to become black holes which emit no light D massive stars are very rare 13 What would happen if mass were continually added to a 2 Solar mass neutron star A The star s radius would increase B The star would eventually become a black hole C The star would erupt as a nova D All of the above would occur 14 The event horizon of a black hole is defined as A the point of maximum gravity B the radius of the original neutron star before it became a black hole C the point at which shock waves emanate from the strong gravitational distortion the black hole creates in the fabric of spacetime D the radius at which the escape speed equals the speed of light 15 If the Sun were to be instantly replaced by a 1 Solar mass black hole the gravitational pull of the black hole on Earth would be A much greater than it is now B the same as it is now C much smaller than it is now D irrelevant because Earth would be quickly obliterated by the strong tidal force of the black hole 16 The Cosmological Principle says that physical laws that are true in one part of the universe must be true in every part of the universe A True B False 17 Edwin Hubble revolutionized astronomy when he made an accurate calculation of the distance to the Andromeda Nebula by spotting a rare Type Ia supernova A True B False 18 In the Great Debate of 1920 Curtis and Shapley argued over whether or not A the Big Bang occurred B the age of the universe was 14 billion years C the spiral nebulae were located outside the Milky Way D life existed outside of Earth 19 What do astronomers mean when they say that the universe is homogeneous A All stars in all galaxies have planetary systems just like ours B The universe looks the same no matter where you look C Galaxies are generally distributed similarly throughout the universe D Generally speaking there is little difference between conditions on Earth in the Sun or in outer space 20 There is no special center to the expansion of the universe A True B False 21 As the universe expands the sizes of galaxies expand a measurable amount as well A True B False 22 Galaxies move away from us in all directions because A the force of gravity strengthens with distance B the force of gravity weakens with distance C space is expanding D our galaxy has expelled all other galaxies 23 The current temperature of the cosmic microwave background radiation is 17 K A True B False 24 The standard Big Bang theory successfully predicts that the fraction of helium by mass in the primordial universe was 2 percent A True B False 25 The cosmic microwave background radiation contains photons left over from the epoch in the universes history when electrons recombined with nuclei A True B False 26 To be a standard candle an object must have a constant A lifetime B brightness C luminosity D distance 27 Hubbles constant H0 represents A the rate of expansion of the universe B the speed at which galaxies are moving away from us C the time it takes a galaxy to move twice as far away from us D the size of the universe 28 We know that spiral galaxies contain dark matter because the gas in the disk rotates with a velocity that decreases in a way that is similar to our Solar System A True B False 29 Dark matter is distributed inside galaxies in exactly the same way as luminous matter although the total mass of dark matter is much larger than that of luminous matter A True B False 30 The disks of spiral galaxies appear blue because A spiral galaxies are moving toward us B spiral galaxies contain mostly hot blue stars C spiral galaxies are still undergoing star formation D spiral galaxies contain more metals that when ionized emit blue light 31 Although elliptical and irregular galaxies have been observed in both dwarf and giant varieties we find only giant spiral galaxies A True B False 32 Which is not one of the three pillars of Big Bang Cosmology A All galaxies are moving away from the Milky Way Galaxy B Spiral Nebula are extragalactic objects C We observe the relic of Big Bang the 2 73K blackbody radiation D We observe 25 of normal matter as Helium 33 The Hubble constant is measured as H0 72 km s Mpc A galaxy located at 0 5 Mpc from us is moving away from us with a speed of A 72 km s B 144 km s C 36 km s D 0 km s 34 Which of the following statement is incorrect A Black hole and wormhole are both solutions of Einstein s equation B They are both end products of stellar evolution C They distort the spacetime D The …