MULTIPLE CHOICE QUESTIONS (50 pts.)Choose the BEST answer to each of the following questions using what you have learned inASTR 101. Indicate your choice on the scantron. (2 pts. each)1. Certain regions viewed with optical telescopes appear black, like the Horsehead Nebula inOrion. Why?A. There are no stars here.B. Black holes limit our view.C. Dust in this region scatters visible photons out of our line of sight.D. The gas in the region absorbs all of the starlight.E. Some regions in space are completely empty.2. The mass limit for a white dwarf star is 1.4 solar masses. Why?A. Above this mass the neutron pressure cannot balance gravity.B. Above this mass the electron pressure cannot balance gravity.C. Below this mass the star becomes a pulsar.D. Below this mass the star becomes a black hole.E. The star would become a supernova below this mass.Gravity wants everything to collapse. In white dwarfs, there is electron degeneracy pressure. Gravity wins above 1.4 solar masses; beyond that, we would have neutron degeneracy pressure. If gravity is strong enough, a black hole is created. 3. An ultraviolet photon has ___________________________ an infrared photon.A. the same energy and wavelength asB. a longer wavelength and more energy thanC. a longer wavelength and less energy thanD. a shorter wavelength and more energy thanE. a shorter wavelength and less energy thanThe shorter the wavelength, the hotter and more energy there is. Cold is to red as blue is to hot.In the OBAFGKM classification/spectrum, O is the hottest and M is the coldest.4. Fluorescence by the gases in the coma of a comet occurs as A. ice turns directly to gas.B. small pebbles come off the nucleus and are carried away by the solar wind.C. ultraviolet photons are absorbed by the gases and visible photons are emitted.D. the temperature of the gases increase as the comet approaches perihelion.E. soon as the comet is close enough to the Sun to feel the effects of its strong magnetic field.5. Sunspots are cooler than the surrounding photosphere becauseA. hot gas clouds in the upper atmosphere cast shadows onto the photosphere.B. magnetic fields inhibited the flow of energy rising to the photosphere from below.C. nuclear fusion has stopped in this part of the photosphere.D. large numbers of neutrinos are exiting the Sun in this region.E. this region has just produced a solar flare.6. The mass of Jupiter was first calculatedA. from analysis of the motions of its moons.B. using its distance from the Sun and its rotational period.C. using its angular size and distance from Earth.D. using data from spacecraft flybys.E. by measuring the time that it takes for the Red Spot to disappear from view.7. Today, the Sun physically will dip below the horizon at 7:50 PM EDT. However, it will remain visible above the horizon for an additional 4 minutes. Why?A. because we live at a northern latitudeB. due to atmospheric refractionC. due to atmospheric reflectionD. because last year was a leap yearE. because the Sun is south of the Celestial Equator8. A study of the stellar spectrum provides information on a star’sA. radial motion.B. composition.C. temperature. Peak wavelength will tell you temperatureD. all of the above.E. only answers A and B9. If there are five objects of the same size that have different temperatures, the coolest objectwould be the one whose most intense wavelength is in the _______ part of the electromagneticspectrum.A. infrared B. red C. blue D. ultraviolet E. X-rayCold stars have spectrum in the red part. Order: Radio, Microwave, Infrared, Visible, UV, X-Rayand Gamma (low energy to high)10. Saturn is 10 times farther from the Sun than Earth. Comparing the intensity of sunlight atSaturn’s distance to the intensity on Earth, what can be said? A. The intensity is the same.B. The intensity is 10 times greater at Saturn.C. The intensity is 10 times less at Saturn.D. The intensity is 100 times greater at Saturn.E. The intensity is 100 times less at Saturn.I is proportional to 1/d^2 (distance)Iearth = 1/1 = 1Isaturn = 1/10^2 = 1/10011. Which planet was at opposition last weekend?A. VenusB. MarsC. JupiterD. SaturnE. Neptune17. Most exoplanets discovered so far are more massive than Jupiter and are closer to their starsthan Mercury. How do planetary system formation theories explain these observations ofexoplanets?A. These exoplanets formed outside the frost line and migrated inward due to drag in the disk.B. These exoplanets formed very close to their stars.C. These exoplanets formed around another star, escaped, and were later captured into orbits close to their current stars.D. These exoplanets spun off a rapidly rotating star and condensed into planets close to their stars.E. These exoplanets were attracted by their star’s magnetic field and moved into a tighter orbit.We know that gas giants cannot form inside the frost line. But certain gases and ices maycondense outside the nebula and we believe that the solar system formed out of a disk of gas. Asthey orbit, they migrate inward because friction slows them down and forces them to spiral in(which causes energy loss). 18. The speed of light through a vacuum isA. greatest for radio waves due to their long wavelength.B. greatest for gamma rays due to their high photon energies.C. greatest for the shortest wavelength photons.D. the same for all types of electromagnetic radiation.E. dependent on the frequency of the electromagnetic radiation.19. The classroom demonstration in which a student was placed in the spinning chair withweights was meant to show what happensA. as a neutron star collapses and its rotation speeds up.B. when gravity is balanced by rotation.C. when a fast-spinning object ejects matter into space.D. as weightlessness takes control.E. to stars in a binary system when one explodes.Conservation of Angular Momentum – smaller things spin faster to conserve angularmomentum. 20. A planetary nebula, like the Ring Nebula shown in class, isA. observational evidence that planets exist around other stars.B. a gas cloud that is about to collapse and form planets.C. a giant molecular cloud that is about to form new stars.D. what is left after a planet blows up.E. gas ejected by a star that is becoming a white dwarf.The Sun will have a last burst of helium fusion, because it has a lot of energy, it will push out theouter shell leaving a ring. A planetary nebula is an emission nebula consisting