AY 101-051                                                    Summer 2011 
                                    QUIZ #6

1. A star becomes a red giant after
	a) ejecting its outer layers as a planetary nebula.
	b) it exhausts all available fusion processes.
	c) hydrogen fusion in its core begins.
	D) THE HYDROGEN IN ITS CORE HAS BEEN (ALMOST) COMPLETELY CONVERTED TO HELIUM.

2. A sunlike star can produce a planetary nebula 
	a) when it completes hydrogen fusion in its core.
	B) AT THE END OF ITS RED-GIANT PHASE.
	c) at the end of its white-dwarf phase.
	d) when it begins core helium fusion.

3. Nova outbursts, and white-dwarf supernovae, are phenomena caused by 
A) BINARY STARS’ INTERACTIONS.		c) young stars beginning nuclear fusion. 
 b) planetary systems.			d) formation of iron cores in stars.

4. As a result both of how stars form and how long they last, the most common kind of main-sequence star is
	a) near the Sun’s mass.			C) A RED DWARF.
	b) the most massive type.			d) a white dwarf.

5.  If we look at star clusters of greater and greater ages, we see that
A) THE BRIGHTEST REMAINING MAIN-SEQUENCE STARS ARE PROGRESSIVELY LOWER IN MASS.
b) there are fewer and fewer red giants.
	c) there are progressively more of the hot stars at the top of the main sequence.
	d) there are fewer red dwarfs.

6. A white dwarf is held up against its own gravity by
	a) its high temperature.				c) pressure of neutrons.
	B) PRESSURE OF ELECTRONS.				d) its powerful magnetic field.

7. When a star leaves behind a black hole, we can detect it most easily if
A) IT HAS A CLOSE COMPANION STAR.
b) we can see the star disappear.
c) it blocks the light of many background stars.
d) the star was rotating rapidly.

8. One kind of supernova explosion is triggered by
   	a) the violent winds of hot stars.
  	 b) the onset of helium fusion in a giant star.
   	c) the helium flash in a red supergiant.
   	D) THE PRODUCTION OF AN IRON-RICH CORE IN A MASSIVE STAR.

9. Discovery of a pulsar in the Crab Nebula showed a direct connection between
	A) SUPERNOVA REMNANTS AND NEUTRON STARS.
	b) supernova remnants and white dwarfs.
	c) planetary nebulae and neutron stars.
	d) star formation and neutron stars. 
          				
10. The order of stellar remnants from least to most massive is:
a)	black hole, neutron star, white dwarf.
B)	wHITE DWARF, NEUTRON STAR, BLACK HOLE.
c)	Neutron star, black hole, white dwarf.
d)	White dwarf, black hole, neutron star.