Week 5 Homework

  1. Why is elemental iron a poor choice for sustained fusion reactions in star cores?
      a. iron can't fuse with the nuclei of other elements.
      b. iron atomic nuclei are too large to fuse.
      c. the energy needed to fuse iron is more than is generated by the fusion.
      d. iron is only found in old degenerate stars.

  2. How would you characterize a star known as a white dwarf?
      a. The remnant left over after a supernova explosion.
      b. The dead remnant of a low to medium mass star.
      c. A pre-supernova high mass star.
      d. A main-sequence star.

  3. What event led to formation of the Crab Nebula?
      a. a supernova explosion and then outward pressure from a pulsar.
      b. acrretion of material from a red giant to a white dwarf.
      c. newborn stars.
      d. interstellar dust clouds collapsing.

  4. Which of the following accurately describe black holes?
      a. A black hole is probably present if a star seems to orbit an unseen mass less than 2 solar masses.
      b. Black holes the vacuum cleaners of space, sucking in everything near them.
      c. The light from a star behind a black hole would have its image distorted.
      d. Black holes can be seen directly with telescopes.

  5. What would happen to the Sun if it were crushed into the size of a black hole.
      a. helium in the core would fuse.
      b. the earth's atmosphere would be removed.
      c. the inner planets would be drawn into the black hole.
      d. the earth would still orbit just as before but it would freeze.

  6. Choose the best description of General Relativity.
      a. gravity is caused by the curved geometry of space and time.
      b. space is absolute and fixed.
      c. the universe is two dimensional.
      d. time is an illusion.

  7. Which statement is incorrect?
      a. neutrinos escape from black holes.
      b. time near a black holes is longer compared to observers farther away.
      c. tidal forces probably "spaghettify" objects near black hole.
      d. black holes are natural result of the collapse of sufficiently massive stars.

  8. The human body contains iron that most likely came from this type of event.
      a. a planetary nebula.
      b. debris from neutron stars.
      c. radioactive decay.
      d. the core of a very massive star that exploded.

  9. Why is light passing near massive objects following a curved path?
      a. the geometry of space is warped by mass of objects.
      b. magnetism.
      c. solar winds.
      d. electron degeneration.

  10. Which of the following has a good chance to escape from inside a black hole?
      a. electrons
      b. gamma photons
      c. neutrinos
      d. none of the above.

  11. Adding mass to a neutron star will eventually cause what result?
      a. a planetary nebula.
      b. a red giant star.
      c. a white dwarf star.
      d. a black hole.

  12. Why are pulsars probably just neutron stars with poles aimed toward earth?
      a. small rotating sources of radiation like neutron stars likely emit pulses.
      b. neutron stars eventually evolve into pulsars.
      c. pulsars and neutron stars are mostly found in planetary nebulae.
      d. pulsars and neutron stars are mostly near the center of our galaxy.

  13. For which theory did Albert Einstein receive the Nobel Prize?
      a. General Relativity
      b. Photo-Electric Effect
      c. Quantum Tunnelling
      d. Special Relativity

  14. What do astronomers think is most likely occupying the center of a black hole?
      a. anti-matter.
      b. a white hole.
      c. a large mass compressed to zero volume.
      d. a wormhole to another part of our galaxy.

  15. Why do astronomers think V404 Cygni is probably a black hole?
      a. there is intense infrared radiation coming from the area.
      b. a nearby star is accelerating.
      c. actually it is probably not a black hole.
      d. its mass is 8 solar masses or more.

  16. Which elements on the periodic table were already manufactured prior to stellar evolution?
      a. hydrogen and most of the helium.
      b. carbon, nitrogen, and oxygen.
      c. uranium, plutonium, and lead.
      d. argon and neon.

  17. What will happen when the Sun's core runs low on hydrogen?
      a. collapse into rapidly spinning neutron star.
      b. lithium will combine with carbon outside the core.
      c. helium in the core will fuse into carbon, nitrogen, and oxygen.
      d. expansion into a blue supergiant.

  18. According to astronomers, the sun will eventually collapse into a black hole.
      a. yes.
      b. no.
      c. possibly, when it runs out of fuel.
      d. only if Jupiter crashes into it.

  19. How do astronomers describe a Planetary Nebula?
      a. planets forming from a proto-planetary disk.
      b. the lost outer layers of a collapsing red giant star.
      c. the remnants from a supernova explosion.
      d. the collapse of hydrogen in a Bok globule.

  20. Which of these best describes a neutron star?
      a. Beams of radiation from both magnetic poles sweep in a circle around the sky.
      b. The diameter of the star is similar to the size of Bellingham.
      c. A spoonful has a mass comparable to Mt. Baker.
      d. All the above