PSU Astro 7N Exam 2 Questions with Answers 100%
Correct!!
A high luminosity star - -Emits more light than a low-luminosity star
-If a red giant appears the same brightness as a red main sequence star, which one is farther
away? - -The red giant
-The heaviest nuclei of all are formed... - -During a supernova explosion
-Hydrogen-2 + proton = ____ + energy: - -Helium-3
-Which of the following has the smallest radius? - -Neutron star
-Why does the main sequence part of a star's life end? - -The hydrogen in the core is
exhausted.
-Which of the following will have the shortest lifetime on the main sequence? - -Main
sequence star with surface temperature 20000 K
-Many of the brightest 100 stars viewed from Earth are not on the main sequence (even
though most stars are) because... - -The most luminous stars are giants and supergiant that
have already finished their main sequence lifetimes
-A 2-solar-mass main sequence star is the same distance as a 0.2-solar-mass main sequence
star. Which star appears brighter? - -The 2 solar mass main sequence star appears brighter
-The temperature of the photosphere of the Sun is closest to... - -6000 Kelvin
-An estimate of the number of communicating/technological civilizations that we expect in our
Galaxy would be a larger number if... - -The average number of planets that could support life
for each star were larger
-If the sun had twice its mass, then which of these planets would be in its habitable zone? - -
Jupiter
-how do astronomers measure the temperature of stars? - -By looking at which absorption
lines are present in the star's spectrum.
-The largest fraction of nearby stars (e.g. within 100 light years) is... - -Red main sequence stars
, -The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the distance to
the star? - -50 parsecs
-Which of the following is the sequence of events for a 40-solar mass star (one of the most-
massive stars)? - -Stellar nursery, protostar, blue star on main sequence, Type 2 supernova,
black hole
-Star A is 9 times as luminous as Star B. The two stars appear the same brightness. What is true
about their distance? - -Star A is 3 times farther away than Star B.
-What is the name of the slightly cooler layer of the Sun just outside the photosphere? - -
Chromosphere
-How does a star move on the H-R diagram during the period of time it is converting hydrogen
to helium in its core? - -It remains nearly fixed at a certain point on the main sequence and does
not move on the H-R diagram.
-If the entire mass of Earth were concentrated in a region the size of a marble, the resulting
object would be... - -A black hole
-Which is the smallest object? - -A neutron star
-A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger than the
rest wavelength of H-alpha. What is the redshift of the galaxy? - -0.1
-Which is the most luminous? - -Quasar
-Which contains the most stars? - -A spiral galaxy
-Galaxy A appears twice the angular size of Galaxy B. Assuming the two galaxies have the same
physical size in kiloparsecs, which of the following is true? - -Galaxy B is 2 times farther away
than Galaxy A
-What fundamental particles make up a Helium-3 atom? - -5 up quarks, 4 down quarks, 2
electrons
-Which statement is FALSE?
A. Planetary nebulae can have layers because of pulsating stars
B. Planetary nebulae usually last tens of thousands of years
C. A planetary nebula will be part of the end state of the Sun
D. Planetary nebulae usually have black holes at their centers
E. Planetary nebulae are a few light years in size - -D. Planetary nebulae usually have black holes
at their centers
Correct!!
A high luminosity star - -Emits more light than a low-luminosity star
-If a red giant appears the same brightness as a red main sequence star, which one is farther
away? - -The red giant
-The heaviest nuclei of all are formed... - -During a supernova explosion
-Hydrogen-2 + proton = ____ + energy: - -Helium-3
-Which of the following has the smallest radius? - -Neutron star
-Why does the main sequence part of a star's life end? - -The hydrogen in the core is
exhausted.
-Which of the following will have the shortest lifetime on the main sequence? - -Main
sequence star with surface temperature 20000 K
-Many of the brightest 100 stars viewed from Earth are not on the main sequence (even
though most stars are) because... - -The most luminous stars are giants and supergiant that
have already finished their main sequence lifetimes
-A 2-solar-mass main sequence star is the same distance as a 0.2-solar-mass main sequence
star. Which star appears brighter? - -The 2 solar mass main sequence star appears brighter
-The temperature of the photosphere of the Sun is closest to... - -6000 Kelvin
-An estimate of the number of communicating/technological civilizations that we expect in our
Galaxy would be a larger number if... - -The average number of planets that could support life
for each star were larger
-If the sun had twice its mass, then which of these planets would be in its habitable zone? - -
Jupiter
-how do astronomers measure the temperature of stars? - -By looking at which absorption
lines are present in the star's spectrum.
-The largest fraction of nearby stars (e.g. within 100 light years) is... - -Red main sequence stars
, -The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the distance to
the star? - -50 parsecs
-Which of the following is the sequence of events for a 40-solar mass star (one of the most-
massive stars)? - -Stellar nursery, protostar, blue star on main sequence, Type 2 supernova,
black hole
-Star A is 9 times as luminous as Star B. The two stars appear the same brightness. What is true
about their distance? - -Star A is 3 times farther away than Star B.
-What is the name of the slightly cooler layer of the Sun just outside the photosphere? - -
Chromosphere
-How does a star move on the H-R diagram during the period of time it is converting hydrogen
to helium in its core? - -It remains nearly fixed at a certain point on the main sequence and does
not move on the H-R diagram.
-If the entire mass of Earth were concentrated in a region the size of a marble, the resulting
object would be... - -A black hole
-Which is the smallest object? - -A neutron star
-A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger than the
rest wavelength of H-alpha. What is the redshift of the galaxy? - -0.1
-Which is the most luminous? - -Quasar
-Which contains the most stars? - -A spiral galaxy
-Galaxy A appears twice the angular size of Galaxy B. Assuming the two galaxies have the same
physical size in kiloparsecs, which of the following is true? - -Galaxy B is 2 times farther away
than Galaxy A
-What fundamental particles make up a Helium-3 atom? - -5 up quarks, 4 down quarks, 2
electrons
-Which statement is FALSE?
A. Planetary nebulae can have layers because of pulsating stars
B. Planetary nebulae usually last tens of thousands of years
C. A planetary nebula will be part of the end state of the Sun
D. Planetary nebulae usually have black holes at their centers
E. Planetary nebulae are a few light years in size - -D. Planetary nebulae usually have black holes
at their centers
