# Astronomy college course/Star (Wikipedia)/questions

Testbank Astronomy_college_course#Star

## AstroWikipStar_Study

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### AstroWikipStar_Study-v1s1

1. Why is a star made of plasma?
    ___ a) it is so hot that electrons are stripped away from the protons
    ___ b) plasma is always present when there are strong magnetic fields
    ___ c) the interstellar gas was mostly plasma
    ___ d) plasma is generic word for "important"
    ___ e) the intense gravity liquifies the substance, just as red blood cells liquify plasma in the body
2. What is the difference between a constellation and an asterism?
    ___ a) asterisms are smaller than constellations
    ___ b) none of these is correct
    ___ c) constellations represent regions of the sky, like state boundaries on a map of the USA
    ___ d) asterisms are larger than constellations
    ___ e) constellations consist of never more than ten stars.
3. Stellar parallax is
    ___ a) Two of these is correct
    ___ b) Triangulation to deduce the distance to nearby stars
    ___ c) Using changes in the angular position of a star to deduce the star’s distance
    ___ d) Using spectral lines to deduce the distance to nearby stars
    ___ e) None of these is correct.
4. Giant molecular clouds with sufficient conditions to form a star cluster would have formed them long ago. Any stellar births in the past couple of billions years probably resulted from _____ between clouds.
    ___ a) photon exchange
    ___ b) collisions
    ___ c) None of these is correct.
    ___ d) ion exchange
    ___ e) Two of these are correct
5. A starburst galaxy.
    ___ a) Two of these are correct
    ___ b) All of these are correct
    ___ c) usually is a result of collisions between galaxies
    ___ d) is a region of active stellar birth
    ___ e) has only dead or dying stars
6. Which of the following expresses Jean's criterion for the collapse of a giant molecular cloud of mass, M, radius, R, and temperature T, and pressure P? (Here ? is some constant)
    ___ a) P>?MR
    ___ b) R>?MT
    ___ c) M>?RT
    ___ d) T>?RM
    ___ e) P>?MT
7. Which of the following changes in the properties of a giant molecular cloud might cause it to collapse?
    ___ a) Decrease mass at fixed temperature and size
    ___ b) Two of these are correct
    ___ c) Increase mass at fixed temperature and size
    ___ d) Increase temperature at fixed mass and size
    ___ e) Increase size at fixed pressure and mass
8. What happens if you increase the size of a giant molecular cloud while keeping temperature and mass fixed?
    ___ a) It is more likely to collapse because this will increase the temperature
    ___ b) It is less likely to collapse because temperature can never be kept fixed
    ___ c) It is more likely to collapse because larger things have more gravity
    ___ d) It is equally likely to collapse because size is not part of the Jean's criterion.
    ___ e) It is less likely to collapse spreading it out weakens the force of gravity
9. What is a Bok globule in the formation of stellar systems?
    ___ a) A black hole that enters a cloud and triggers the collapse
    ___ b) A small planet that formed before any stars have formed
    ___ c) A supernovae precurser that attracts more gas atoms
    ___ d) A small portion of a giant cloud that collapses
    ___ e) A cluster of giant molecular clouds that coalesce to form a solar system
10. Pre–main sequence stars are often surrounded by a protoplanetary disk and powered mainly by
    ___ a) the release of gravitational energy
    ___ b) chemical reactions
    ___ c) the fission of Carbon from Helium
    ___ d) collisions between protoplanets
    ___ e) the fusion of Helium to Carbon
11. Stars that begin with more than 50 solar masses will typically lose _______ while on the main sequence.
    ___ a) 10% of their magnetic field
    ___ b) 10% their mass
    ___ c) 1% their mass
    ___ d) 50% their mass
    ___ e) all of their magnetic field
12. The Hayashi and Henyey tracks refer to how T Tauri of different masses will move
    ___ a) through a cluster as they are born
    ___ b) through an HR diagram as they are born
    ___ c) Two of these are true
    ___ d) through a cluster as they die
    ___ e) through an HR diagram as they die
    ___ a) Decreasing luminosity with no change in temperature
    ___ b) Increasing luminosity with no change in temperature
    ___ c) Increasing temperature with no change in luminosity
    ___ d) Decreasing temperature and increasing luminosity
    ___ e) Decreasing temperature with no change in luminosity
14. When a star with more than 10 solar masses ceases fuse hydrogen to helium, it
    ___ a) it fuses helium to carbon to iron (and other elements), then continues to release more energy by fusing the iron to heavier elements such as uranium.
    ___ b) it fuses helium to carbon and other elements up to iron and then ceases to produce more energy
    ___ c) ceases to convert nuclear energy.
    ___ d) it fuses helium to carbon and then ceases to produce more energy
    ___ e) it fuses elements up to uranium, and continues to produce energy by the fission of uranium.
15. Many supernovae begin as a shock wave in the core that was caused by
    ___ a) electrons being driven into protons to form neutrons
    ___ b) iron fusing into heavier elements such as uranium
    ___ c) the conversion of carbon into diamonds,
    ___ d) all of these processes contribute to the shock wave
    ___ e) carbon and other elements fusing into iron
16. A dying star with more than 1.4 solar masses becomes a ______, and those with more than 5 solar masses becomes a _____
    ___ a) blue giant....red giant
    ___ b) white dwarf....black hole
    ___ c) neutron star....black hole
    ___ d) white dwarf....neutron star
    ___ e) white dwarf...red dwarf
17. According to Wikipedia, a star with over 20 solar masses converts its Hyrogen to Helium in about 8 billion years, but the conversion of Oxygen to heavier elements take about _____
    ___ a) 1 thousand years
    ___ b) 10 billion years
    ___ c) 1 year
    ___ d) 1 million years
    ___ e) 1 billion years

#### Key to AstroWikipStar_Study-v1s1

1. Why is a star made of plasma?
    + a) it is so hot that electrons are stripped away from the protons
    - b) plasma is always present when there are strong magnetic fields
    - c) the interstellar gas was mostly plasma
    - d) plasma is generic word for "important"
    - e) the intense gravity liquifies the substance, just as red blood cells liquify plasma in the body
2. What is the difference between a constellation and an asterism?
    - a) asterisms are smaller than constellations
    - b) none of these is correct
    + c) constellations represent regions of the sky, like state boundaries on a map of the USA
    - d) asterisms are larger than constellations
    - e) constellations consist of never more than ten stars.
3. Stellar parallax is
    + a) Two of these is correct
    - b) Triangulation to deduce the distance to nearby stars
    - c) Using changes in the angular position of a star to deduce the star’s distance
    - d) Using spectral lines to deduce the distance to nearby stars
    - e) None of these is correct.
4. Giant molecular clouds with sufficient conditions to form a star cluster would have formed them long ago. Any stellar births in the past couple of billions years probably resulted from _____ between clouds.
    - a) photon exchange
    + b) collisions
    - c) None of these is correct.
    - d) ion exchange
    - e) Two of these are correct
5. A starburst galaxy.
    + a) Two of these are correct
    - b) All of these are correct
    - c) usually is a result of collisions between galaxies
    - d) is a region of active stellar birth
    - e) has only dead or dying stars
6. Which of the following expresses Jean's criterion for the collapse of a giant molecular cloud of mass, M, radius, R, and temperature T, and pressure P? (Here ? is some constant)
    - a) P>?MR
    - b) R>?MT
    + c) M>?RT
    - d) T>?RM
    - e) P>?MT
7. Which of the following changes in the properties of a giant molecular cloud might cause it to collapse?
    - a) Decrease mass at fixed temperature and size
    - b) Two of these are correct
    + c) Increase mass at fixed temperature and size
    - d) Increase temperature at fixed mass and size
    - e) Increase size at fixed pressure and mass
8. What happens if you increase the size of a giant molecular cloud while keeping temperature and mass fixed?
    - a) It is more likely to collapse because this will increase the temperature
    - b) It is less likely to collapse because temperature can never be kept fixed
    - c) It is more likely to collapse because larger things have more gravity
    - d) It is equally likely to collapse because size is not part of the Jean's criterion.
    + e) It is less likely to collapse spreading it out weakens the force of gravity
9. What is a Bok globule in the formation of stellar systems?
    - a) A black hole that enters a cloud and triggers the collapse
    - b) A small planet that formed before any stars have formed
    - c) A supernovae precurser that attracts more gas atoms
    + d) A small portion of a giant cloud that collapses
    - e) A cluster of giant molecular clouds that coalesce to form a solar system
10. Pre–main sequence stars are often surrounded by a protoplanetary disk and powered mainly by
    + a) the release of gravitational energy
    - b) chemical reactions
    - c) the fission of Carbon from Helium
    - d) collisions between protoplanets
    - e) the fusion of Helium to Carbon
11. Stars that begin with more than 50 solar masses will typically lose _______ while on the main sequence.
    - a) 10% of their magnetic field
    - b) 10% their mass
    - c) 1% their mass
    + d) 50% their mass
    - e) all of their magnetic field
12. The Hayashi and Henyey tracks refer to how T Tauri of different masses will move
    - a) through a cluster as they are born
    + b) through an HR diagram as they are born
    - c) Two of these are true
    - d) through a cluster as they die
    - e) through an HR diagram as they die
    + a) Decreasing luminosity with no change in temperature
    - b) Increasing luminosity with no change in temperature
    - c) Increasing temperature with no change in luminosity
    - d) Decreasing temperature and increasing luminosity
    - e) Decreasing temperature with no change in luminosity
14. When a star with more than 10 solar masses ceases fuse hydrogen to helium, it
    - a) it fuses helium to carbon to iron (and other elements), then continues to release more energy by fusing the iron to heavier elements such as uranium.
    + b) it fuses helium to carbon and other elements up to iron and then ceases to produce more energy
    - c) ceases to convert nuclear energy.
    - d) it fuses helium to carbon and then ceases to produce more energy
    - e) it fuses elements up to uranium, and continues to produce energy by the fission of uranium.
15. Many supernovae begin as a shock wave in the core that was caused by
    + a) electrons being driven into protons to form neutrons
    - b) iron fusing into heavier elements such as uranium
    - c) the conversion of carbon into diamonds,
    - d) all of these processes contribute to the shock wave
    - e) carbon and other elements fusing into iron
16. A dying star with more than 1.4 solar masses becomes a ______, and those with more than 5 solar masses becomes a _____
    - a) blue giant....red giant
    - b) white dwarf....black hole
    + c) neutron star....black hole
    - d) white dwarf....neutron star
    - e) white dwarf...red dwarf
17. According to Wikipedia, a star with over 20 solar masses converts its Hyrogen to Helium in about 8 billion years, but the conversion of Oxygen to heavier elements take about _____
    - a) 1 thousand years
    - b) 10 billion years
    + c) 1 year
    - d) 1 million years
    - e) 1 billion years

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