Astro 4
A red subgiant star is one that has a
decreasing surface temperature and nearly constant brightness
In an evolved high-mass star, when the electrons combine with protons to form a pure neutron core, the reaction
generates a neutrino burst
Nuclear fusion requires high temperatures because nuclei
repel each other
The first red giant stage of a one solar-mass star's life usually ends with
an explosion in the helium core
High protostellar winds of ejected gas occur
between the initial contraction and the ignition of nuclear burning.
For stars on the main-sequence, stars with decreasing mass have
decreasing surface temperature and absolute brightness
In oder to use a spectroscopic parallax to find the distance to a star, you need to know
the spectral type and luminosity class (B2V for example) and the apparent magnitude
Which of the following magnitude corresponds to the dimmest star?
+4
The mass of a carbon atom is 12.00 amu while the mass of a helium-4 atom is 4.003 amu. If a gamma ray photon splits a carbon atom into three Helium Atoms, how much energy is converted into mass?
0.009amu
The mass of a carbon atom is 12.00amu while the mass of deuterium atom is 2.014amu. If six deuterium atoms fuse to form a carbon atom, how much mass is converted into energy
0.084amu
Suppose that the color and behavior of a star identify it as a type that we know has absolute magnitude 4.8. If the star's apparent magnitude is found to be 14.8, how far away is it?
1,000 parsecs
The velocity of sound waves is roughly the same for all wavelengths. Suppose that a sound wave has a wavelength of one meter and frequency of 500Hz. The wavelength of a 1000 Hz sound wave would then be
1/2 m
A star with a distance modulus of zero is at a distance of
10 parsecs
Our Sun is expected to last for about 10 billion years. Which of these is a likely lifespan for a star with 20 times the mass of our Sun?
10-15 million years
Our Sun is a G2V star with absolute magnitude 4.8. Suppose that a star of spectral type G2V is observed to have apparent magnitude 9.8. How far away is it?
100 parsecs
Compared to a magnitude 6 star, a magnitude 1 star would be
100 times as bright
A star that is observed to have an apparent brightness in which is 10 to the power of -4 times its absolute brightness. How far away is it
1000
Barnard's star is a near neighbor of the Sun whose properties we know quite well. It is a type M4V with absolute magnitude 13.22. Suppose that another star of spectral type M4V is observed to have apparent magnitude 23.22. How far away is it?
1000 parsecs
A star at a distance of 1000pc should have an apparent brightness equal to its absolute brightness multiplied by
10^6
a star whose apparent brightness is 1/100 that of a sixth magnitude star would have magnitude
11
Our own Sun has an absolute visual magnitude of 4.8. A starship that travels 10 parsecs from our Sun and looks back at the Sun will see it as having apparent visual magnitude
4.8
The violent lines in the Hydrogen spectrum are normally seen with wavelengths 410 nm and 434 nm. In the light of a star that is moving toward us, we might expect to see those lines at wavelengths of
400 nm and 424 nm
Suppose that you went to double all of the dimensions of a telescope that uses a large lens to collect light. The amount of glass that you need to form the lens of the new, twice as large, telescope is
8 times the amount needed for the original telescope
A type Ia Supernova occurs when
a white-dwarf begins to collapse
Type II supernovas have the following properties
a spectrum with hydrogen lines and a variable maximum brightness.
In a particular binary system, we are able to determine the masses of both stars in the system as well as the angle between our line of sight and the plane of the stars' orbits but cannot determine the diameters or atmospheric compositions of the two stars. This system is most likely
a visual binary system
A nova occurs when
a white dwarf steals fuel from a neighbor.
The temperatures of a gas measures the
energy of motion of its atoms or molecules
Stars that are much more massive than our sun
form faster and burn out faster
To measure the heliocentric stellar parallax of a star, you mostly need a telescope with
high resolving power
for stars on the main-sequence, stars with increasing mass have
increasing surface temperature and absolute brightness
On a HR Diagram, a visible white dwarf is in the
lower left corner
The mass of Betelgeuse is about 20 times the mass of our own Sun. Our Sun is expected to have a total life span of about 10 billion years. The life span of Betelgeuse is expected to be
much shorter
The Earth's motion around the Sun causes
nearby stars to shift back and forth once a year
The wavelength of the sound waves that correspond to middle-C is about 4 feet. If you are standing 4 feet away from a piano that is playing that note, then between you and the piano there will usually be
one region of maximum pressure
To see small but bright objects such as the ice caps on Mars, you would need a telescope with large
resolving power
A spectroscopic binary star system is one in which we see
spectral lines shifting back and forth
When the hydrogen fuel runs out at the center of a main sequence star, the star
swells up and becomes a red giant
The average energy of motion of an atom or molecule in a gas is called its
temperature
The size of a typical white dwarf star is comparable to the size of
the Earth
During the Tau Tauri phase of a protostar's evolution,
the brightness decreases
A mirror that is shaped like a shallow bowl sitting on the table with its open end facing up will focus light that comes
vertically down from above
A spectral type G star could be main sequence star like our own Sun or it could be one of several different types of red giant stars. Can we tell which it is just by looking at its spectrum?
yes. the widths of the spectral lines tell us which it is
