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

Star version A

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1 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"

2 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.

3 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

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.

	None of these is correct.
	collisions
	photon exchange
	ion exchange
	Two of these are correct

5 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

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)

	P>?MT
	M>?RT
	R>?MT
	P>?MR
	T>?RM

7 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

8 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.

9 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

10 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

11 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

12 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

13

How do low-mass stars change as they are born?

Birth of stars HR path tracks

	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

14 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.

15 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

16 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

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 _____

	1 thousand years
	1 year
	1 billion years
	1 million years
	10 billion years