Astronomy 100 Week 6 Name________________________ Where is our solar system located?

Name________________________Where is our solar system located?a. In the disc of the Milky Way Galaxy but at its outer edge, about 100,000 light years from the center.b. Above the disc the Milky Way Galaxy and about 10,000 light years from the center.c. At the outer edge of the the Milky Way galactic bulge, about 10,000 light years from the center, in the plane of the disc.d. In the disc of the Milky Way Galaxy and about 30,000 light years from the center.How did Edwin Hubble use Cepheids variable stars to prove that M31 is a galaxy outside the Milky Way Galaxy?a. He measured the geometric parallax of the Cepheid in Andromeda, was able to determine the distance to it, and showed that it was far outside the Milky Way Galaxy.b. From the period-luminosity correlation for Cepheids, he was able to determine the distance to Andromeda and show that it is far outside the Milky Way Galaxy.c. There are no Cepheids in the Milky Way, so his discovery proved that it had to be in another galaxy.d. Since a Cepheid is a type of luminous galaxy, when he found it in Andromeda he was able to prove that Andromeda was a separate super-galaxy from the Milky Way.Who discovered the relationship between the fluctuating period of variable stars, and their intrinsic brightness?a. Edwin Hubbleb. Annie Cannonc. Harlow Shapleyd. Henrietta LeavittWhy are light sources with a 21cm wavelength useful to astronomers?a. They let astronomers learn about the process of star formation by mapping the distribution of hydrogen molecular gas.b. They are used to study distant stars in the Galaxy痴 halo and corona because these signals penetrate the dust in the Galaxy's disk.c. They let astronomers map the large-scale motion and distribution of atomic hydrogen gas in the Milky Way.d. They let astronomers "see" through molecular hydrogen gas into the Milky Way痴 black holes.If astronomers observe a star at the inner part of the disk (about 10,000 light-years from the center) of a spiral galaxy and measure its orbital speed to be 125 km/s, how does the mass of the galaxy compare with the mass of our Milky Way galaxy?a. The galaxy's mass (inside the star's orbit) is more than that of our Milky Way galaxy.b. The galaxy's mass (inside the star's orbit) is about the same as that of our Milky Way galaxy.c. The galaxy's mass (inside the star's orbit) is less than that of our Milky Way galaxy.d. Without more information about the mass of the orbiting star, we cannot answer the question.Shapley determined the location of the center of our Galaxy by estimating distances to:a. Cepheid variable stars clustered near galactic center.b. The geometric center of all bright blue, massive stars located in the galaxy's spiral arms.c. Globular clusters distributed throughout a large halo.d. A visually bright, massive object around which all objects in the Galaxy move.What type of variable star did Shapley REALLY use to determine the distances to globular clusters in the Milky Way?a. T-Tauri starsb. RR Lyrae variablesc. Type I Cepheid variablesd. Wolf-Rayet starsWhat are you likely to find if you visit the halo of our galaxy?a. gas and dust and emission and reflection nebulaeb. open clusters full of newly born starsc. globular clusters containing mostly very old starsd. lots of very hot blue starse. all of the aboveWhy are sun-like (one solar mass) stars good tracers for the locations of the spiral arms in the Milky Way galaxy?a. Sun-like stars form in spiral arms and remain in the spiral arms near to the location where they originate.b. Sun-like stars form in spiral arms and move along the same spiral toward the center of the galaxy.c. Sun-like stars can form anywhere in the disk, but migrate gravitationally to the nearest spiral arm, where they then spend the rest of their life.d. Nonsense - only the very massive, luminous stars are good spiral arm tracers in spiral galaxies.The strongest evidence to date for a 2.6 million solar mass black hole at the center of our galaxy is from which of the following observations?http://antwrp.gsfc.nasa.gov/apod/ap021018.htmla. X-ray intensity versus time of radiation from an accretion disk: the time variations imply the source is too compact to be anything except a black hole.b. A star passing within a light-day of galactic center at more than 1% of light speed, as measured at infrared wavelengths.c. The orbit of Sun-like stars orbiting within a few light-years of galactic center, as measured by optical telescopes through a hydrogen-alpha filter (656 nm).d. Only "a" and "b" above.Where are the oldest stars in the galaxy to be found?a. In the spiral arms and the core.b. In the core and the halo.c. In the halo and the spiral arms.d. Evenly distributed.Which of the following is an actual observation that falsifies (is inconsistent with) the theory that the Milky Way galaxy originated from the collapse of a spherical gas cloud that flattened into a disk?a. We observe fewer white dwarf stars in the galactic disk than there should be for an 11-billion year old galactic disk.b. The globular cluster stars in the galaxy halo are all old.c. The metallicity of globular cluster stars is about one tenth the Sun's value.d. Nonsense - all of the above observations are consistent with the standard collapse-from-a-cloud theory.Which of the following is a correct list of distance indicators (standard candles) used by astronomers?a. emission and reflection nebulae in molecular clouds; nova explosions on white dwarfs; main-sequence starsb. white dwarf stars; Cepheid variables; black hole binary systems; massive star supernovaec. lyra and cepheid variable stars; white-dwarf supernovaed. emission by super-massive black holes located at the center of nearly every large galaxy; spinning spiral galaxiesWhich of the following arguments supports the idea that large elliptical galaxies formed by mergers of smaller galaxies?a. Big ellipticals lack gas and dust, and galactic collisions can allow central supermassive black holes to consume all pre-existing gas and dust.b. Big ellipticals are generally found near the center of rich galaxy clusters containing many individual galaxies.c. Ellipticals have lots of gas and dust, and collisions can spur star formation that also forms gas and dust.d. All the above arguments support the idea of galaxy mergers forming big elliptical galaxies.Dwarf detonation supernovae (type Ia) are useful standard candles for measuring large distances becausea. the periodicity of the light curve is tightly correlated with the peak luminosity.b. the exploding star has about the same mass and composition in each case, it is bright, and the light curve is always the same.c. the explosion is recurrent, and the time between explosions correlates with the peak luminosity.d. the rotation rate of the object is easily measured and correlates with the peak luminosity.e. none of the above supernovae are useless for measuring distancesWhich of the following is a result of stellar evolution in all spiral and irregular galaxies over long time periods, in the absence of galaxy merger?a. a continuing increase in the number of white dwarfs, neutron stars, and stellar black holes.b. a continuing increase in percentage of heavy elements in the interstellar medium.c. a continuing decrease of the mass of hydrogen in the interstellar medium.d. a continuing decrease in the rate of star formation with time.e. All of the aboveWhat is the best description of the mass of the Milky Way Galaxy?a. Several million times the mass of the Sun.b. Several hundred million times the mass of the Sun.c. Several billion times the mass of the Sun.d. Several hundred billion times the mass of the Sun.Which of the following is supporting evidence for the existence of dark matter?a. the shape of the rotation curve for elliptical galaxiesb. the relatively high-speed motion of stars in the haloc. hot, diffuse hydrogen/helium gas observed (via X-rays) in clusters of galaxiesd. all of the aboveGravitational interactions between two or more galaxies can result ina. compression of gas/dust clouds and rampant star formation.b. the stripping of gas and dust from one of the galaxies, resulting in the shut-down of future star formation and long 'tails' of gas.c. a change of shape for the galaxies entering the interaction.d. a merger of the two or more galaxies into one larger galaxy.e. all of the above.Suppose you are in an alternate Universe, and you observe that distant galaxy clusters exhibit blue-shifts proportional to distance. What would you conclude?a. That the Universe is contracting and that it will come together at some point in the future.b. That intergalactic dust caused the apparent blue-shift because of preferential scattering of blue light by dust particles.c. That the Universe is expanding and will continue to expand into the future.d. That the Universe is in a steady state, with no average expansion or contraction.