Astronomy college course/Star (Wikipedia)/questions/Original version of this quiz

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