Astro 6: Stars, Galaxies and the Universe Exam 1 Review

Overview of Exam Structure

  • The exam consists of three sections:

    • Multiple Choice

    • Fill in the Blank

    • True or False

  • Each question is worth 2 points, totaling 100 points for 50 questions. There is an additional short answer extra credit question at the end.

Multiple Choice Section

Questions 1 - 20

  1. Proper scientific notation for the mass of the Sun:

    • a) $1.9884 \times 10^{30}$ kg

    • b) 1988400000000000000000000000000 kg

    • c) $0.19984 \times 10^{31}$ kg

  2. Reason we see the ink on this page as black:

    • a) It reflects all colors of visible light

    • b) It does not reflect visible light

    • c) It emits black light

    • d) It is made of many small black holes

  3. Correct order of the electromagnetic spectrum from shortest to longest wavelength:

    • a) Radio, Infrared, Visible, Ultraviolet, X-ray, Gamma ray

    • b) X-ray, Gamma ray, Ultraviolet, Infrared, Visible, Radio

    • c) Gamma ray, X-ray, Ultraviolet, Visible, Infrared, Radio

  4. Photon with the highest energy:

    • a) A red photon

    • b) An X-ray photon

    • c) An infrared photon

    • d) A green photon

  5. Photon with the highest frequency:

    • a) A radio photon

    • b) A blue photon

    • c) An infrared photon

    • d) A green photon

  6. Photon visibility from State College (latitude = 40.8°N):

    • a) Polaris (dec = +89.3°)

    • b) Andromeda (dec = +41.3°)

    • c) The Milky Way center (dec = -29°)

    • d) The Tarantula Nebula (dec = -69.1°)

  7. Photon flux observer location comparison:

    • a) Observer on Earth's moon

    • b) Observer on Mars

    • c) They would observe the same photon flux

  8. Most effective location for an X-ray telescope:

    • a) On a mountain in the Arizona desert

    • b) On the roof of Davey Lab in State College

    • c) In space

  9. Reason for modern telescopes being reflectors:

    • a) Aberrations and dispersion in glass make it difficult to focus all colors of light

    • b) Mirrors are easier to engineer and maintain

    • c) Mirrors can be at the base of the telescope, making them easier to support

    • d) All of the above are correct

  10. Process responsible for energy generation in the Sun:

    • a) Hydrogen fusing into helium via the proton-proton (p-p) chain

    • b) Hydrogen fusing into helium via the CNO cycle

    • c) Helium fusing into carbon via the triple-alpha process

    • d) All of the above are correct

  11. Outcome for a white dwarf exceeding the Chandrasekhar limit (1.4 solar masses):

    • a) Explode as a core-collapse supernova

    • b) Explode as a type Ia supernova

    • c) Collapse into a black hole

    • d) Return to the main sequence forever

  12. Comparative capability of JWST (8m diameter mirror) and Hubble (2.5m diameter mirror):

    • a) JWST will have better angular resolution

    • b) JWST will be able to see fainter objects in the same exposure time

    • c) All of the above are correct

  13. Basic nucleosynthesis processes:

    • a) Add a proton

    • b) Add an electron

    • c) Add a neutron

    • d) Add an alpha particle

  14. Cause of Earth's seasonal changes:

    • a) The distance from the Sun

    • b) The variable output of energy from the Sun

    • c) The tilt of Earth's rotational axis relative to its orbit

    • d) All of the above

  15. Reason Sirius is brighter than Rigel despite being less massive:

    • a) More massive than Rigel

    • b) Larger radius than Rigel

    • c) Closer to Earth than Rigel

    • d) All of the above are correct

  16. Mirror principle of hydrostatic equilibrium in a star:

    • a) As the core contracts, the outer layers will respond by contracting

    • b) As the core gets hotter, the outer layers will start fusing hydrogen

    • c) As the core contracts, the outer layers will respond by expanding

    • d) As the core collapses into a black hole, the outer layers will also become black holes

  17. Current location of the Sun on the H-R diagram:

    • a) A

    • b) B

    • c) C

    • d) D

    • e) E

  18. Final evolutionary stage location of the Sun on the H-R diagram:

    • a) A

    • b) B

    • c) C

    • d) D

    • e) E

  19. Most massive star consideration:

    • a) A

    • b) B

    • c) C

    • d) D

    • e) E

  20. Longest main sequence life consideration:

    • a) A

    • b) B

    • c) C

    • d) D

    • e) E

Fill in the Blank Section

Questions 21 - 35

  1. Your zenith refers to the sky directly above you.

  2. Definition of Mass: Mass is the amount of matter that makes up an object.

  3. Weightlessness Explanation: Astronauts and other objects in freefall experience weightlessness due to the lack of a surface pushing against them.

  4. According to Kepler's Laws, planets follow elliptical orbits around the Sun.

  5. The 5800 K temperature quoted for the Sun refers to the temperature of the photosphere, the visible surface of the Sun.

  6. A(n) black hole is created when a dense enough mass causes so much curvature in spacetime that not even light can escape.

  7. A(n) pulsar is a rapidly rotating neutron star which produces a jet that acts like a lighthouse, with observable signals at evenly spaced time intervals.

  8. A(n) brown dwarf is a ‘failed star’ that never got massive and hot enough to fuse hydrogen into helium via the p-p chain.

  9. The Zodiac constellations are those which follow the ecliptic, the path that the Sun travels relative to the Earth in a year.

  10. A(n) helium flash is the brief burst of runaway triple-alpha nuclear fusion when a low mass star becomes a red giant.

  11. A low-mass star will shed its outer layers in a(n) planetary nebula at the end of the red giant phase.

  12. The Algol paradox states that stars in a(n) binary system can exchange mass to the point where the originally less massive star becomes more massive than the companion.

  13. A molecular gas cloud undergoes fragmentation into smaller clouds which then collapse to form protostellar disks.

  14. A(n) emission spectrum is observed from light emitted from electrons cascading from higher energy states to lower energy states.

  15. Planets are likely to maintain a(n) atmosphere if they are more massive, farther from the star, and have colder gases.

True or False Section

Questions 36 - 50

  1. False color images are made by stacking single-filter exposures and assigning colors in the visible portion of the electromagnetic spectrum to each filter. True/False

  2. A disperser with resolving power $R=100$ will be able to differentiate spectral features with smaller wavelength separations than a disperser with resolving power $R=1000$. True/False

  3. A G-type star will live longer on the main sequence than a B-type star. True/False

  4. All cultures tell the same stories about the origins of the stars. True/False

  5. The radial velocity method is likely to find Earth-like exoplanets around Sun-like stars. True/False

  6. Gold (atomic number Z=79) is most likely formed during neutron star mergers. True/False

  7. Glowing lava shows a thermal continuum (blackbody) spectrum. True/False

  8. Continuous spectra exist because photons of any energy can be absorbed and emitted by a hydrogen atom. True/False

  9. The Moon likely formed somewhere far off in the solar system and was captured by Earth's gravity. True/False

  10. Satellite constellations (e.g., Starlink) and other objects in low-Earth orbit are sources of light pollution. True/False

  11. A star 10 pc from Earth will have a parallax angle of 10 arcseconds. True/False

  12. Stars moving away from an observer will exhibit a blueshift in their spectrum. True/False

  13. The transit method is biased in favor of detecting face-on planetary systems. True/False

  14. There are more low-mass stars than high-mass stars. True/False

  15. Radius determines nearly all intrinsic properties of a star. True/False