When is/was gravitational contraction an important energy-generation mechanism for the Sun?
when the Sun was being formed from a collapsing cloud of gas
What do we mean when we say that the Sun is in gravitational equilibrium?
There is a balance within the Sun between the outward push of pressure and the inward
pull of gravity.
From the center outward, which of the following lists the "layers" of the Sun in the correct
core, radiation zone, convection zone, photosphere, chromosphere, corona
Suppose you put two protons near each other. Because of the electromagnetic force, the two
repel each other
Why must the Sun's rate of fusion gradually rise over billions of years?
Fusion reactions decrease the overall number of particles in the core, causing the core to
shrink, converting gravitational potential energy into thermal energy, and increasing the
rate of fusion.
Studies of sunquakes, or helioseismology, have revealed that
our mathematical models of the solar interior are fairly accurate
Which statement best describes the solar neutrino problem?
Solar neutrinos have been detected, but in fewer numbers than predicted by theoretical
What is a possible solution to the solar neutrino problem?
The electron neutrinos created in the Sun change into another type of neutrino that we do
The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of
that light was released by fusion in the solar core about
a million years ago.
What happens to energy in the convection zone of the Sun?
Energy is transported outward by the rising of hot plasma and the sinking of cooler
Which of the following statements about the sunspot cycle is not true?
The rate of nuclear fusion in the Sun peaks about every 11 years.
Approximately, what basic composition are all stars born with?
three-quarters hydrogen, one-quarter helium, no more than 2 percent heavier elements
Since all stars begin their lives with the same basic composition, what characteristic most
determines how they will differ?
mass they are formed with
If the distance between us and a star is doubled, with everything else remaining the same, the
remains the same, but the apparent brightness is decreased by a factor of four.
Suppose you measure the parallax angle for a particular star to be 0.1 arcsecond. The distance
to this star is
Suppose that you measure the parallax angle for a particular star to be 0.5 arcsecond. The
distance to this star is
Suppose you see two main-sequence stars of the same spectral type. Star 1 is dimmer in apparent
brightness than Star 2 by a factor of 100. What can you conclude? (Neglect any effects that
might be caused by interstellar dust and gas.)
Star 1 is 10 times more distant than Star 2.
Which of the following terms is given to a pair of stars that we can determine are orbiting each
other only by measuring their periodic Doppler shifts?
Which of the following best describes the axes of a Hertzsprung-Russell (H-R) diagram?
surface temperature on the horizontal axis and luminosity on the vertical axis
On a Hertzsprung-Russell diagram, where would we find stars that have the largest radii?
On a Hertzsprung-Russell diagram, where on the main sequence would we find stars that have
the greatest mass?
You observe a star in the disk of the Milky Way, and you want to plot the star on an H-R
diagram. You will need to determine all of the following, except the
rotation rate of the star.
Why are Cepheid variables so important for measuring distances in astronomy?
Their luminosity can be inferred from their period.
Which of the following statements about an open cluster is true?
All stars in the cluster are approximately the same age.