Test 1
The collapse of the core is high-mass stars naturally explains all but which of the following neutron star properties
A large distance from Earth
Which of the following is false
A scientific theory is an undisputed fact
The Earth is located approximately
About halfway out from the center of the Milky Way
A hypothesis may become a theory
After many repeated attempts to falsify it fail
If you observe a star, you will see
An absorption spectrum
When you see a pattern in nature, it is usually evidence of
An underlying physical law
One of the central assumptions in astronomy is that the physical laws of nature
Are the same everywhere in the universe
What is the difference between brightness and luminosity
Brightness is how much light we see from a star; luminosity is how much light it emits
Essentially all the elements heavier than iron our Milky Way were formed
By supernovae
The interstellar medium is divided up into three different kinds of gas clouds. These are
Cold gas at 100 K, warm gas at 8000 K, and hot gas at about 1 million K
What is one way in which high-mass stars differ from low-mass stars
Convection is important in their cores, which mixes up helium throughout the core
Parallax is used to measure a star's
Distance
How is the distance to a star related to its parallax
Distance is inversely proportional to parallax
For an object in hydrostatic equilibrium, if the temperature inside the object were to increase, the object would
Expand
We can identify only a fraction of all the radio pulsars that exist in our Galaxy because
Few swing their beam of synchrotron emission in our direction
The source of the energy for a collapsing protostar comes from
Gravitational potential energy
Which of the following traits does not help slow or prevent the collapse of a gas cloud?
High mass
Stars that have spectral type B are ___ in temperature compared with stars that have spectral type M
Hotter
A protostar's evolutionary "track" in the H-R diagram traces out
How the protostar's luminosity, temperature, and radius change with time
A red giant with the same mass as the Sun generates energy from
Hydrogen burning to helium in a shell surrounding its core
On a typical H-R diagram, where are the white dwarfs located?
In the lower left corner
On a typical H-R diagram, where are the hottest main-sequence stars located?
In the upper left corner
On a typical H-R diagram, where are the stars with the largest radii located
In the upper right corner
If a main-sequence star's core temperature increased, fusion reaction rates would ___ because the protons would be moving ___
Increase; faster
The most massive elements such as those that make up terrestrial planets like Earth were formed
Inside stars and supernovae
In the quantum mechanical view of the atom, electrons are often depicted as
Is a cloud that is centered on the nucleus
What does it mean to say that an object is in thermal equilibrium?
It is absorbing the same amount of energy that it is radiating
How does the speed of light traveling through a medium (such as air or glass) compare to the speed of light in a vacuum?
It is always less than the speed of light in a vacuum
What is the most likely explanation for a dark area in the night sky surrounded by a dense field of stars
It is region with thick dust blocking the starlight coming from behind
The faster-moving star in a binary is the
Less massive star
The Hertzsprung-Russell diagram is a graph of ___ for stars
Luminosity vs. temperature
A nova is the result of which explosive situation
Mass transfer onto a white dwarf
The average density of the interstellar medium is
Much less than the best vacuum on Earth
What critical event transforms a protostar into a normal main-sequence star?
Nuclear fusion begins in the core
Albert Einstein is best known for his revolutionary theory of
Relativity
Massive stars explode when they
Run out of nuclear fuel in their cores, and the cores collapse
A spaceship is traveling toward the Earth while giving off a constant radio signal with a wavelength of 1 meter. What will the signal look like to people on the Earth
Signal with a wavelength less than 1 meter
Type Ia (white dwarf) and Type II (massive star) supernovae can be distinguished by what combination of observations
Spectra and light curves
Star A and Star B appear equally bright in the sky. Star A is twice as far away from the Earth as Star B. How do the luminosities of Stars A and B compare?
Star A is four times as luminous as Star B
Which of these stars would have the biggest redshift?
Star moving at high speed away from you
The dominant mechanism by which high-mass stars generate energy on the main-sequence is called
The CNO cycle
The Local Group is in the environment around
The Milky Way that contains a few dozen galaxies
You observe a red star and a blue star and are able to determine that they are the same size. Which star has a higher surface temperature, and which star is more luminous?
The blue star has a higher surface temperature and is more luminous
Why do some stars in the sky appear blue, whereas other stars appear red?
The blue stars have higher surface temperatures than the red star
Which of the following is not directly measurable from the absorption lines of a star?
The distance to the star
The Milky Way is the name of
The galaxy in which we live
Binary star systems are extremely useful in studying stars because they allow us to determine
The stars' masses
Stars evolve primarily because
They use up the fuel in their cores
The Sun eventually will become a
White dwarf
In the first stage of the protostar's evolution on the H-R diagram, the protostar's temperature ____ and the luminosity ____
increases; decreases
