Instructions: For matching questions, write the letter of the best answer on the blank line next to the number of the problem. For multiple choice questions, simply circle the letter of the one best answer. For short answer questions, write the correct answer in the blank space provided. Each of the multiple choice, matching, and short answer questions is worth 1 point. For the essay questions write your essays in the test booklet. Each essay question is worth 10 points. The combined total of all questions is 150 points.

1. The temperature of the Sun’s surface, the photosphere, is approximately

1. 580^o K
2. 5,800^o K
3. 58,000^o K
4. 580,000^o K

1. The Sun displays a variety of dramatic and irregular features such as sunspots, plages, prominences and flares. Most of these are surface features are effected by

1. The interaction of the solar plasma with the Suns’ magnetic field
2. Random processes in the Earth’s magnetosphere
3. The emission of neutrinos from the Sun’s core
4. None of the above

1. The interstellar medium is comprised of gas and dust. The most abundant component is

3. Carbon
4. Silicates

1. As gravity causes a nebula to collapses to form a star several processes resist the collapse. What process allows the hot compressed protostar to leak out energy, allowing the collapse to continue?

1. Gas pressure
2. Interstellar magnetic fields
3. Angular momentum
4. Infrared radiation

1. All the stars that are in the hydrogen-burning phase of their lives

1. are located well above the main sequence
2. can be found anywhere on the H-R diagram
3. are located in the white dwarf region
4. are located on the main sequence
5. can be found in the red giant region

1. After the Sun has completed its red-giant phase, the Sun

1. will go through a supernova outburst and end its existence as a white dwarf
2. will contract and move into the blue supergiant region where it will burn carbon and other exotic nuclear fuels
3. will probably go through the ejection of its outer envelope as a planetary nebula leaving a white dwarf
4. will become a neutron star emitting an intense beam of radiation that will sweep around the sky as the Sun rotates

1. Pulsars are probably

1. two white dwarfs in a binary system
2. rotating neutron stars
3. collapsing black holes
4. explosive main-sequence stars

1. We can measure the distance to nearby stars using geometric parallax, that is, measuring the slight change in position of background stars compared with our star of interest as seen from the Earth at opposite positions in it’s orbit around the Sun. For more distant stars, we can use an H-R diagram and the luminosity class of a star to estimate the stars distance using what technique?

1. Red-shift number
2. Cepheid variables
3. Spectroscopic parallax
4. Galactic luminosity

1. If I know the apparent magnitude, m, and the distance, d, of an astronomical object, I can use the distance-modulus formula to determine the

1. Modulus of the star.
2. The mass of the star.
3. The elemental composition of the star.
4. The absolute magnitude of the star.

1. Which type of binary star observation allows the estimate of the masses of each of the stars in the binary system/

1. Double star
2. Single-line binary
3. Double-line binary
4. All of the above

1. In the late 18^th century, William Herschel mapped the location of all the stars in an attempt to locate the postion of the Solar system in the Milky Way galaxy. He found that the solar system appeared to be at the center of all the visible stars and hence at the center of the Milky Way. His analysis ignored what complication?

1. Most stars in the Milky Way are comprised of dark matter
2. Dust in the disk of the Milky Way severely obscure visible observations
3. Globular clusters are gravitationally bound to the galaxy
4. The Doppler shift due to the Solar Systems’ motion about the galactic center

1. To which part of the Milky Way galaxy does the Sun belong?

1. a member near the Orion spiral and in the disk of the Galaxy
2. a member of the nuclear bulge population of the nucleus
3. a member of the halo stars of the Galaxy
4. none of the above

1. About how far apart are stars in our part of the galaxy?

1. 5 AU
2. 5 light years
3. 5,000 light years
4. 5 million light years

1. Hubble used these to measure the distance to ‘nebula’ to determine if they were galactic or extragallactic sources.

1. Spectroscopic binaries
2. Cepheid variables
3. Supernova
4. Radio lobes

1. Which of the following is thought to be correct concerning galaxies?

1. The spectrum of a galaxy has the general appearance of being the composite of the spectra of a large number of stars.
2. The most distant galaxies seem to be approaching our Milky way galaxy
3. Galaxies rarely collide
4. none of the above

1. From the motion of galaxies, we estimate that the universe is comprised mostly of

1. Luminous matter—stars, galaxies, photons, etc
2. Dark matter—brown dwarfs, weakly interaction massive particles, neutrinos, and other exotic, weakly interacting matter

1. Active galactic nuclei typically generate double-lobed radio sources. These lobes generate their radio waves due to

3. the destruction of stars as they are torn apart by the tidal forces of the AGN black hole
4. synchrotron radiation from relativistic electrons moving in large magnetic fields generated by the AGN

1. Which of the following statements is true regarding the Big Bang theory?

1. In an expanding universe objects may lie beyond our visible horizon so that at some point in the future they will enter our horizon.
2. The time at which space began expanding in the universe is called the big bang.
3. Because the universe is homogeneous on the largest scales, the curvature of space globally is uniform, whether it is closed, flat, or open.
4. all of the above
5. none of the above

1. An analogy for the expansion of the universe in the big bang theory is the surface of a balloon with lady bugs on the surface. Which statement is not an accurate part of this analogy?

1. The surface of the balloon represents our three dimensional space.
2. The ladybugs represent matter, galaxies, planets, etc
3. The surface of the balloon appears flatter as the balloon expands
4. Galaxies expand as the universe expands

1. The Drake equation provides a speculative estimate of the number of civilizations in our Milky Way galaxy who live on planets similar to the Earth and have an intelligence and technology similar enough to ours in order that they could communicate messages to us at the present time over the vast distances of space. According to estimates by Drake, as shown in the textbook and the class lecture, the number of such civilizations is estimated to be

1. Less than 1
2. Approximately 10
3. Approximately 10,000
4. Approximately one million

Essay Question. Choose ONE of the following two questions and write a short essay in the test booklet below. Be concise, but use enough detail, terminology, and quantitative information to provide thorough answer. Draw figures where appropriate. A one page answer should suffice, but a second page is provided if necessary. (10 points)

E1. Describe the interior layers (structure) of the Sun, how energy is generated, and how the energy makes its way to the outer layers of the Sun to be radiated into space.

or

E2. Explain how stars are classified by the Hertzsprung-Russell diagram. Draw a picture of an H-R diagram and locate where the different types of stars are located.