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CH 21 HW
A white dwarf can dramatically increase in brightness only if it
is descended from a very massive star. |
has another star nearby. |
can avoid nuclear fusion in its core. |
is spinning very rapidly. |
Which of the following stars will become hot enough to form elements heavier than oxygen?
Check all that apply.
A star that is half the mass of the Sun. |
A star having the same mass as the Sun. |
A star that is twice as massive as the Sun. |
A star that is eight times more massive than the Sun |
A massive star becomes a supernova when it
collides with a stellar companion. |
forms iron in its core. |
suddenly increases in mass. |
suddenly increases in surface temperature. |
The radius of a white dwarf is determined by a balance between the inward force of gravity and the outward push of electron degeneracy pressure..
A(n) nova occurs when hydrogen fusion ignites on the surfaces of a white dwarf in a binary system.
A(n) massive star supernova occurs when fusion creates iron in the core of a star.
A white dwarf in a close binary system will explode as a supernova if it gains enough mass to exceed the white dwarf limit (1.4 solar masses).
A(n) accretion disk consists of hot, swirling gas captured by a white dwarf (or neutron star or black hole) from binary companion star.
A(n) white dwarf supernova can occur only in a binary system, and all such events are thought to have the same luminosity.
A nova differs from a supernova in that the nova
involves only high-mass stars. |
is much less luminous. |
is much more luminous. |
can occur only once. |
Figure 21.8 in the textbook ("Supernova Light Curves") indicates that a supernova whose luminosity declines steadily in time is most likely associated with a star that is
on the main sequence. |
more than eight times the mass of the Sun. |
without a binary companion. |
comparable in mass to the Sun. |
An observable supernova should occur in our Galaxy about once every
year. |
decade. |
century. |
millennium. |
Which of the following is not evidence for supernovae in our Galaxy?
The existence of iron on Earth. |
The existence of binary stars in our Galaxy. |
The rapid expansion and filamentary structure of the Crab nebula. |
Historical records from China and Europe. |
Using the light curve in Figure 21.8 in the textbook, estimate how long after the peak brightness the supernova will become too faint to be seen.
about 40 days |
about 70 days |
about 170 days |
about 120 days |
The silver atoms found in jewelry originated in
the core of a red-giant star. |
a supernova. |
a nearby galaxy. |
the core of the Sun. |
Nuclear fusion in the Sun will
never create elements heavier than helium. |
create elements up to and including oxygen. |
create all elements up to and including iron. |
create some elements heavier than iron. |
Most of the carbon in our bodies originated in
nearby galaxy. |
supernova. |
the core of a red-giant star. |
the core of the Sun. |
Elements like oxygen, magnesium, and silicon are produced by
all stars |
massive stars only |
low-mass stars only |
A massive star will collapse when iron is produced in the core because
When iron fuses it generates much more energy than the previous elements in the core. |
Iron will not fuse, so the core doesn't produce energy to oppose the inward gravitational pull of the star. |
The iron circulates to the outer part of the star, and since iron is very dense, the star will collapse. |
Iron is dense enough to exert a much greater gravitational pull on the outer layers of the star. |
Because the Earth contains elements heavier than iron, we know that the solar nebula was enriched due to:
the destruction of another planet. |
a planetary nebula. |
a Type II supernova. |
a nova. |
a Type I supernova. |
Nearly all the elements found in nature were formed inside stars, EXCEPT for:
helium and carbon. |
silver and technetium. |
carbon and silicon. |
uranium and radium. |
hydrogen and helium.  |
NoteStudied by 10 peopleNoteStudied by 41 peopleNoteStudied by 173 peopleNoteStudied by 11 peopleNoteStudied by 4 peopleNoteStudied by 4 people