- How should we expect the Milky Way's interstellar medium to be different in 50 billion years than it is today?a. The total amount of gas will be much greater, since many stars will undergo supernovae between now and then.b. The total amount of gas will be about the same, but the percentage of elements heavier than hydrogen and helium will have risen from the current 2% to more than 50%.c. Thanks to the recycling of the star-gas-star cycle, the interstellar medium should look about the same in 50 billion years as it does today.d. The total amount of gas will be much less than it is today.
- What evidence suggests that most of the mass of the Milky Way is in the form of dark matter?a. Our view of distant galaxies is often obscured by dark blotches, which are presumably made of dark matter.b. Although dark matter emits no visible light, we have detected its radio emissions.c. The orbital speeds of stars far from the galactic center are surprisingly high.d. Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk.
- What is the notation of a first inversion in a triad?
- What is the Young Prince and Princess famous for?
- Over time, the star-gas-star cycle leads the gas in the Milky Way to _________.a. become denser and hotterb. have a lower abundance of heavy elementsc. have a greater abundance of heavy elementsd. become denser and have a greater abundance of heavy elements
- Suppose you want to observe and study the radiation from gas inside an interstellar bubble created by a supernova. Which of the following observatories will be most useful?a. the Chandra X-ray Observatoryb. the Keck I telescope on the summit of Mauna Keac. the SOFIA airborne infrared observatoryd. the Hubble Space Telescope
- Red and orange stars are found evenly spread throughout the galactic disk, but blue stars are typically found _________.a. only in or near star-forming cloudsb. in the haloc. only in the central bulged. also evenly spread throughout the galactic disk
- Most nearby stars move relative to the Sun at speeds below about 30 km/s. Suppose you observe a nearby star that is moving much faster than this (say, 300 km/s). Which of the following is a likely explanation for its high speed?a. It has been pushed to high speed by the shock wave from a nearby supernova.b. It is a very young star, recently formed.c. It is probably a halo star that is currently passing through the disk.d. It is a very high mass star.
- Which of the following statements is not true of the object known as Sgr A* in the center of our Galaxy?a. It is a source of X-ray emission that we have observed with telescopes in space.b. It is thought to harbor a black hole of about 4 million solar masses.c. It is a source of bright radio emission.d. It is by far the brightest source of visible light lying in the direction of the galactic center.
- Applying the Newton's version of Kepler's third law (or the orbital velocity formula) to the a star orbiting 40,000 light-years from the center of the Milky Way galaxy allows us to determine ______.a. the percentage of the galaxy's mass that is made of dark matterb. the mass of the black hole thought to reside in the center of the galaxyc. the mass of the Milky Way Galaxy that lies within 40,000 light-years of the galactic centerd. the total mass of the entire Milky Way Galaxy
- How would you expect a star that formed recently in the disk of the galaxy to differ from one that formed early in the history of the disk?a. It should be higher in mass.b. It should be much brighter.c. All of the above would be expected.d. It should orbit the galactic center at a much higher rate of speed.e. It should have a higher fraction of elements heavier than hydrogen and helium.
- Which of the following statements comparing halo stars to our Sun is not true?a. Most stars in the halo are less luminous than the Sun.b. Most stars in the halo have either died or are in their final stages of life, while the Sun is only in about the middle of its lifetime.c. Most stars in the halo have cooler surface temperatures than the Sun.d. Most stars in the halo contain a much lower percentage of heavy elements than the Sun.
- What is the best evidence for an extremely massive black hole in the center of the Milky Way?a. The orbits of stars in the center of the galaxy indicate that the presence of an approximately 4 million solar mass object in a region no larger than our solar system.b. The center of our galaxy hosts a pulsar that is spinning so fast that it could only be a black hole.c. Huge amounts of X-rays are pouring out of the center of the galaxy.d. We observe stars vanishing in the center of the Galaxy as they are sucked into the black hole.
- How does the interstellar medium affect our view of most of the galaxy?a. It prevents us from seeing most of the galactic disk with visible and ultraviolet light.b. It absorbs all wavelengths of light.c. It produces so much visible light that it blocks our view of anything beyond it.d. It has no effect on visible-light observations, but prevents us from studying the galactic center with radio waves or X rays.
- If we could see our own galaxy from 2 million light-years away, it would appear _________.a. like a single, dim starb. to fill the sky with widely spaced starsc. as a flattened disk with a central bulge and spiral armsd. as a faintly glowing band of light stretching all the way around the sky
- Who wrote Symphony No. 3, Symphony No. 5, and Moonlight Sonata?
- All the following types of objects are found almost exclusively in the disk (rather than the halo) of the Milky Way except _________.a. globular clustersb. young starsc. high-mass, red supergiant starsd. x-ray binaries
- How did star formation likely proceed in the protogalactic cloud that formed the Milky Way?a. The protogalactic cloud gradually formed stars, starting from the outer edges of the spiral arms and working inward.b. The stars that formed first eventually settled into a galactic disk, circling the center of the galaxy.c. The stars that formed first could orbit the center of the galaxy in any direction at any inclination.d. The protogalactic cloud gradually formed stars, starting from the center of the galaxy working outwards.
- Suppose a scientist holds a press conference at which he claims that 10% of the matter in the Milky Way is in the form of dust grains. Does his claim seem reasonable? Why or why not?a. The 10% figure is too low, because most of the mass of the galaxy is in the form of interstellar dust.b. The 10% figure is too high because there are not enough heavy elements to make that much dust.c. It is reasonable, because we already know that interstellar dust obscures our view through the disk of the galaxy.d. It seems reasonable as long as we assume that red giant stars - which produce dust grains in their stellar winds - are more common than we thought.
- The most common form of gas in the disk of the Milky Way galaxy is _________.a. atomic hydrogen gasb. gas in stellar windsc. molecular hydrogend. gas in hot bubbles