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

/13/. How do low-mass stars change as they are born?
 * ___ 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

/13/. How do low-mass stars change as they are born?
 * + 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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 * Study guide
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