Units 3 & 4 Flashcards
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 nucleus of all formed…
during a supernova explosion
Hydrogen-2 + proton = ______ + energy
Helium-3
Which of the following has the smallest radius?
A: type A main sequence star
B: main sequence star with surface temperature 8000 K
C: type K main sequence star
D: white dwarf
E: neutron star
E: 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?
A: main sequence star with surface temperature 20000 K
B: main sequence star with surface temperature 3000 K
C: main sequence star with luminosity one tenth that of the Sun
D: the Sun
E: main sequence star with mass 2 times the Sun’s
A: 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 supergiants that have already
finished their main sequence lifetimes.
A 2-solar-mass main sequence star is at 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
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How do astronomers measure the temperature of stars?
By looking at which absorption lines are present in the star’s spectrum.
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The largest fraction of nearby stars (e.g., within 100 light years) are …
red main sequence stars
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The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the
distance to the star?
50 parsecs
What 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 II 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 distances?
Star A is 3 times farther away than Star B.
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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
What 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
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Which is the most luminous?
A: nova
B: supernova
C: quasar
D: the Sun
E: white dwarf
C: quasar
Which contains the most stars?
A: an open star cluster
B: a globular star cluster
C: a spiral galaxy
D: the Solar System
E: the alpha Centauri star system
C: 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?
A: Galaxy A is 2 times farther away than Galaxy
B: Galaxy B is 2 times farther away than Galaxy
C: Galaxy A and B are at the same distance.
D: Galaxy A is 4 times farther away than Galaxy
E: Galaxy B is 4 times farther away than Galaxy
B: Galaxy B is 2 times farther away than Galaxy
What fundamental particles make up a Helium-3 atom?
5 up quarks, 4 down quarks, 2 electrons
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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
Which statement is TRUE?
A: Stars form in molecular clouds, where temperatures are about 10 Kelvin.
B: A cloud will collapse and form stars if its mass is a lot less than its Jeans mass.
C: A nova outburst typically only happens once in a star’s life.
D: Stars usually form in isolation, far away from other stars
E: The Crab supernova, in our galaxy, went off about 8 years ago
A: Stars form in molecular clouds, where temperatures are about 10 Kelvin.
How tiny a spot is the Hubble Deep Field?
The size of President Roosevelt’s eye on a dime held at arm’s length.
Among these choices, what is the last thing that happens in the history of the Universe?
A: electrons join with nuclei to make atoms
B: quarks join together to make protons and neutrons
C: nucleosynthesis
D: the Planck epoch
E: the Big Bang expansion begins
A: electrons join with nuclei to make atoms
If a galaxy had no dark matter, we would observe …
the rotation velocity would decrease with increasing distance like the
Keplerian curve in our Solar System
How many times bigger is the Local Group of galaxies in which the Milky Way
resides than the Milky Way itself?
about 100 times bigger
Which one of the following is FALSE?
A: Irregular galaxies, although small, often have a lot of star formation taking
place in them.
B: Barred spiral galaxies have similar properties to normal spirals, except for
the “bar” feature.
C: Galaxy collisions destroy most of the stars in the galaxies involved.
D: Most galaxies appear to be receding from the Milky Way Galaxy.
E: Most elliptical galaxies contain only old stars.
C: Galaxy collisions destroy most of the stars in the galaxies involved.
If a galaxy is moving away from us the wavelength of the light it emits will be …
increased.
The stars in the halo of our Milky Way Galaxy are …
older and redder than those in the disk.
The supermassive black hole in the center of the Milky Way has a mass of …
4 million solar masses
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Which force has the photon as its boson?
electromagnetic
Which mysterious phenomena do scientists attribute to dark energy?
The increasing rate of expansion of the Universe.
Why can we NOT see back the whole way to the time Big Bang expansion began?
The radiation scatters off matter frequently so the Universe is opaque.
What are the “standard candles” that were used to determine the Universe is
accelerating?
Type Ia supernovae
An older star cluster …
has a main sequence turnoff farther to the right on the H-R diagram.
Which of the following statements is TRUE?
A: One or two supernova are observed to go off in the Milky Way galaxy
each year.
B: Type II supernovae are produced by the death of a massive star.
C: Type Ia supernovae show a lot of strong hydrogen lines in their spectra.
D: Type Ia supernovae are produced when a neutron star collapses to become a
black hole.
E: When a planetary nebula is produced it can outshine an entire galaxy.
B: Type II supernovae are produced by the death of a massive star.
If the radius of Star A is twice the radius of Star B, but both have similar temperatures, how do their luminosities compare?
Star A is four times as luminous as Star B.
When using different points in the Earth’s orbit as a baseline for a parallax experiment it is best to do the observations…
6 months apart.
A star is stable due to the balance of…
gravity and gas pressure.
Star “A” is three times farther away from the Sun than Star “B.” The parallax angle of Star “B” is…
three times larger than that of Star “A.”
If a red giant appears the same brightness as a red main sequence star, which one is
farther away?
the red giant
How do astronomers measure the temperature of stars?
By looking at which absorption lines are present in the star’s spectrum.
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Most stars …
A: have larger radii than the Sun.
B: are red giants.
C: end their lives as black holes.
D: are more luminous than the Sun.
E: are less massive than the Sun.
E: are less massive than the Sun.
After doubling the distance from a light source, a light detector collects …
one quarter as much light
You measure the parallax angle of a star to be 0.05 arcseconds. How far away is it?
20 parsecs
What is the first step in the p-p chain?
a proton combines with a proton to make Hydrogen-2 (Deuterium)
Which of the following is the only property of a star that depends on its distance
from the observer?
brightness
The most successful early planet finding mission, launched in 2009, was called …
Kepler
Which of the following is TRUE?
A: life does not exist in the darkness of Earth’s seas
B: more massive stars have habitable zone farther away from them
C: K type stars can’t have planets around them
D: the habitable zone has temperatures low enough that water can freeze
E: less massive stars than the Sun are more luminous than the Sun
B: more massive stars have habitable zone farther away from them
Which of the following is TRUE?
A: habitable planets have been found around red dwarfs as well as around
Sun-like stars
B: the Kepler mission has discovered many supernova explosions
C: the first planets found, in 1992, were in orbit around a G0 type main
sequence star
D: all extrasolar planets were discovered after 2001
E: planets the mass of Jupiter cannot exist at distances less than 1AU from their stars
A: habitable planets have been found around red dwarfs as well as around
Sun-like stars
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Which is roughly the size of Earth?
A: a black hole
B: an M type main sequence star
C: a neutron star
D: a red giant
E: a white dwarf
E: a white dwarf
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Which is the hottest part of the Sun?
Core
“Slurpy’s” home planet was at a distance of 0.55AU from its parent star. And it was
habitable. Because of this, we knew …
it was an M type star.
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An “onion skin” shell burning structure, with elements up to iron being produced,
develops in …
a star much more massive than the Sun
If the Sun had twice its mass, then which of the planets would be in its
habitable zone?
Jupiter
Which chemical element cannot be produced in the core of any star?
Gold
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
How many stars are there in the observable universe?
(based on the Hubble Deep Field Academy activity that you did)
10^22 stars
Why do you suppose the Cat’s Eye Nebula has a certain symmetry?
Bipolar jets are creating matching shapes on both sides.
The largest stars are almost the size of …
our Solar System.
What populations of stars are relatively old?
Globular clusters
What type of radiation does dark matter emit?
None
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What elements are in the Cassiopeia A supernova remnant?
A: oxygen
B: sulfur
C: hydrogen
D: nitrogen
E: all of the above
E: all of the above
How many times bigger are galaxies than individual stars?
billions or trillions of times bigger
How do you measure the mass of the supermassive black hole at the center of the
Milky Way?
look at the orbits of nearby stars and apply Kepler’s third law
What is at the center of the Crab Nebula, that produces its magnetic field?
A neutron star
How many “up” and “down” quarks make up a proton?
Two ups and a down
What happens to the planets in a galaxy when that galaxy collides with
another galaxy?
Nothing, because the spaces between stellar systems in a galaxy is much
larger than their size.
What is so special about Type Ia supernova that make them good distance
indicators?
their luminosities are known.
What is the boson for the strong force?
gluon
The redshifts of galaxies are found to be larger …
for galaxies that are farther away.
True or False? The primary evidence for an accelerating universe comes
from observations of young stars in the Milky Way.
False; in order to measure accelerating expansion, we need to measure
the distances of objects billions of light-years away.
The supermassive black hole in the center of the Milky Way has a mass of …
4 million solar masses
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What parameters does Hubble’s law relate to each other?
galaxy recession velocity and distance
Which force has the photon as its boson?
electromagnetic
How have astronomers interpreted the unexpectedly fast rotation of galaxies?
There must be a lot of dark matter whose gravity can be felt but not seen.
What are the differences between open star clusters and globular star clusters?
open clusters are less concentrated, younger, and have fewer stars
If light takes 4 billion years to reach us from a distant galaxy, how many times
farther away is that distant galaxy than the Andromeda galaxy, which is 2 million
light-years away?
2,000 times
Which contains the most stars?
A: the Solar System
B: an open star cluster
C: a globular star cluster
D: the alpha Centauri star system
E: a spiral galaxy
E: a spiral galaxy
