ASTR 53052

subject Type Homework Help
subject Pages 27
subject Words 3386
subject Authors Eric Chaisson, Steve McMillan

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Supergiant stars are burning different fuels in several shells around the core.
If the value of H has not changed since the Big Bang, then H = 70 km/s/Mpc will give a
Hubble Time of about 14 billion years.
As with stars, binary galaxy pairs are useful in finding their total mass.
The transition from single to multicellular life took over two billion years.
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Jupiter's atmosphere looks uniform and calm, with no visible detail.
As with our own Sun among the neighboring stars, most galaxies in the Local Group
are smaller and dimmer than our own Milky Way.
The instability strip shows that not all main-sequence stars are, in fact, stable.
The solar corona is much cooler than the Sun's surface, hence we must wait for a total
solar eclipse to glimpse it with the naked eye.
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According to Kepler's third law, if you know the planet's orbital period, you can find its
average distance from the Sun.
An hour of right ascension corresponds to 60 degrees in the sky.
Einstein originally added a cosmological constant to his equations to prevent a
presumably static universe from either contracting or expanding. Modern cosmologists
have reintroduced it to their equations, where as the source of dark energy it causes the
universe to expand ever faster.
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Copernicus believed the Earth was the center of all celestial motion.
The Galileo probe was deliberately steered into Jupiter's atmosphere, ending its
mission.
A parsec is about 3.3 light-years.
A neutron star is what remains after a Type II supernova explosion has destroyed the
rest of the star.
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The rotation curve for our Galaxy shows stars beyond the Sun moving slower than
expected.
Most radio telescope searches for signs of intelligent life are performed in the water
hole.
Most of the neutrinos given off by the Sun are changing form in the eight minutes
before they reach us.
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Kepler's third law relates the square of the planet's orbital period in years to the cube of
its average distance from the Sun in astronomical units.
Shapley found the globular cluster distribution equally concentrated all along the
galactic plane.
The water hole lies between 18 and 21 cm in wavelength in the radio spectrum.
Emission nebula, such as M42, are much brighter than planetary nebulae, so are better
suited for finding the distances to other galaxies.
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The Phoenix lander on Mars failed to confirm the presence of water ice under the
surface.
A type B star is bluer than a type G star.
Our Sun lies about the middle of the main sequence and the H-R diagram.
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At its equinoxes, Saturn's rings are most open and double the planet's brightness.
Cassini's probe Huygens returned images of what may have been a shoreline on Saturn.
All jovian planets have rings around their equators and at least eight moons.
The Great Dark Spot of Neptune is probably just as long-lived as the more famed Great
Red Spot of Jupiter; both lie at about the same latitudes, and are about the same size,
relative to their planet.
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A G2V star would be the same temperature as a G2Ib star, but much smaller and less
luminous.
Helium fusion requires a higher temperature than hydrogen fusion.
Any main-sequence star over 25 solar masses will probably retain enough matter in its
core after its supernova to make a black hole.
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The Doppler effect can reveal the rotation speed of a star by the splitting of the spectral
lines.
Only low mass stars experience the temporary instability of the helium flash; high mass
stars go directly into heavier element formation.
A type B9 star is hotter than a type A0 star.
The cosmological principle is the ultimate extension of the Copernican principle to the
entire universe, in that there is no center at all.
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NASA has found definite proof for the past existence of life on Mars.
The weak magnetic field of Europa may originate from a rapidly rotating liquid iron
core.
Alone of all the Galilean moons, Callisto shows no sign of plate tectonics.
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Before it arrived in orbit about Eros, the NEAR spacecraft visited
A) Venus.
B) the Moon.
C) Mars.
D) the asteroid Mathilde.
E) the asteroid Gaspra.
Large molecules found in meteorites and interstellar clouds are evidence that
A) life is abundant in the galaxy.
B) life has definitely formed in other places than Earth.
C) chemical evolution has taken place elsewhere in the universe.
D) organic molecules are extremely rare.
E) life originated on Mars before Earth.
You note that a particular star is directly overhead. It will be directly overhead again in
A) 1 hour.
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B) 12 hours.
C) 23 hours 56 minutes.
D) 24 hours.
E) 24 hours 4 minutes.
The largest difference between Mars' northern and southern hemispheres is that
A) the southern appears older, with more impact craters.
B) the northern has all the outflows and must have been much hotter.
C) the northern is higher overall, despite some high volcanoes in the south.
D) the southern has a polar cap, but none ever forms in the north.
E) the southern is much darker, with large mare-like basaltic lava flows.
Which statement is true about the interstellar medium?
A) Gas contains a lot of carbon atoms.
B) Dust blocks the longest electromagnetic wavelengths.
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C) Gas obscures the light from distant stars.
D) We know more about the gas than the dust.
E) Dust is spread uniformly through the galaxy.
The solar neutrinos observed on Earth come from the hot spots in the corona.
The nearest lobe radio galaxy to our Milky Way is
A) the Whirlpool, M51.
B) Centaurus A.
C) M13 in Hercules.
D) M42 in Orion.
E) M87 in Virgo.
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The critical temperature to initiate the proton-proton cycle in the cores of stars is
A) 3,000 K.
B) 5,800 K.
C) 2,300,000 K.
D) 10 million K.
E) 100 million K.
Which of the following characterizes a shield volcano?
A) It sits above a hot spot in the planet's mantle.
B) It is formed by moving tectonic plates.
C) It can erupt only briefly before being dragged off the hot spot.
D) It cannot get as high as Mt. Everest before the thin crust starts slumping.
E) It cannot grow very large, for it has a very short span of eruption.
A star in the instability strip of the H-R diagram would
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A) vary in both temperature and radius.
B) explode as a Type I supernova.
C) vary in temperature and brightness, but not in radius.
D) vary in brightness with an irregular pattern.
E) vary in temperature and radius, but not in brightness.
Most pulsars have a measured mass of
A) about 1.4 solar masses.
B) less than 1.0 solar masses.
C) between 2 and 4 solar masses.
D) 5.2 solar masses.
E) greater than 10 solar masses.
If a source of light is approaching us at 3,000 km/sec, then all its waves are
A) blue shifted by 1%.
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B) red shifted by 1%.
C) not affected, as c is constant regardless of the direction of motion.
D) blue shifted out of the visible spectrum into the ultraviolet.
E) red shifted out of the visible into the infrared.
What is one of the differences between Cepheids and RR Lyrae variables?
A) Cepheids are giants, but RR Lyrae stars are still on the main sequence.
B) All Cepheids have the same brightness, but RR Lyrae stars vary greatly in
luminosity.
C) The period-luminosity relation holds only for RR Lyrae stars.
D) The pulsations of RR Lyrae stars are much less regular than those of Cepheids.
E) The RR Lyrae stars have much shorter periods than Cepheids.
Rigel has an apparent magnitude of + 0.18 and Betelgeuse an apparent magnitude of
+0.45. What can you conclude from this?
A) Rigel must be closer to Earth.
B) Betelgeuse must be closer to Earth.
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C) Rigel is brighter than Betelgeuse.
D) Betelgeuse is brighter than Rigel.
E) Both stars are brighter than the full moon.
The jovian planets
A) all lie less than 5 AU from the Sun.
B) all have rings around their equators.
C) all spin slower than the Earth.
D) have satellite systems with less than 4 moons.
E) are all much more dense than any of the terrestrial planets.
Which of these is true about the seasons of Uranus?
A) With a tilt of 29 degrees, they are not that different from our solstices and equinoxes.
B) Its strange tilt produces extreme seasonal variations, especially at the poles.
C) At the Uranian equator, the Sun would pass overhead every sixteen hours.
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D) At the Uranian pole the Sun sets every 16 hours during the summer and winter.
E) There are no seasons at the poles.
In shape and component stars, elliptical galaxies are most like our own
A) galactic center.
B) spiral arms.
C) nuclear bulge.
D) halo.
E) companions, the Magellanic Clouds.
A planet whose distance from the Sun is 3 AU would have an orbital period of how
many Earth-years?
A) 3
B)
C)
D) 9
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E) 81
Planetary orbits
A) are evenly spaced throughout the solar system.
B) are highly inclined to the ecliptic.
C) are almost circular, with low eccentricities.
D) have the Sun at their exact center.
E) are spaced more closely together as they get further from the Sun.
A method for identifying a black hole is to
A) look for voids in the star fields.
B) look for its effects on a nearby companion.
C) locate a visible star that disappears when the black hole passes in front of it.
D) search for radio waves from the accretion disk.
E) search for their pulsar signal.
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Most of the mass of our Galaxy lies
A) between Earth and the Galactic center.
B) in the bright spiral arms.
C) outside the luminous part of the Milky Way Galaxy.
D) at the galactic center.
E) within the bulge.
The discovery of the cosmic microwave background was important because
A) it established a firm center of the universe.
B) it was experimental verification of a prediction from the Big Bang theory.
C) it proved that astronomy at radio wavelengths was possible.
D) its detection was a major advance in microwave testing.
E) it showed the universe must be closed, with more than the critical density here.
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The two forms of electromagnetic (E-M) radiation that experience the least atmospheric
opacity are
A) visible light and radio waves.
B) visible light and infrared waves.
C) microwaves and radio waves.
D) X and gamma radiation.
E) ultraviolet and infrared waves.
Which statement about stellar motion is incorrect?
A) Radial velocity is measured by the Doppler shifts of the spectral lines.
B) Proper motion is measured in intervals of six months.
C) You must also know the parallax to get the transverse velocity.
D) The closer stars usually show larger proper motions.
E) The space velocity can be found from the radial and transverse velocities.
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Which of these was NOT seen telescopically by Galileo?
A) sunspots
B) Venus' phase cycle
C) Four moons around Jupiter
D) stellar parallax
E) craters and mare on the Moon
If the Moon appears half lit, and is almost overhead about 6:00 AM, its phase is
A) waxing crescent.
B) first quarter.
C) full.
D) third quarter.
E) waning crescent.
Emission nebulae like M42 occur only near stars that emit large amounts of
A) visible light.
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B) microwaves.
C) ultraviolet radiation.
D) infrared heat.
E) X-rays and gamma rays.
The primary purpose of a telescope is to
A) collect a large amount of light and bring it into focus.
B) magnify distant objects.
C) separate light into its component wavelengths.
D) make distant objects appear nearby.
E) measure the brightness of stars very accurately.
Which statement about extrasolar planets found to date is true?
A) All are terrestrials, comparable in size to Earth.
B) Few are found by Doppler shifts of their stars, due to their gravity.
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C) All lie more than 2 AU from their star.
D) Most have orbital periods of more than a year.
E) Some are so close to their stars that their periods are just a few days.
Which statement about Population II is false?
A) They are made of almost nothing but hydrogen and helium.
B) Their orbits around the Galaxy resemble those of comets.
C) They formed first as the Galaxy formed.
D) At almost five billion years old, our Sun must belong to this older Population.
E) The globular clusters are their most obvious groupings.
What can you conclude about a Type I supernova?
A) It was originally a low-mass star.
B) It was originally a high-mass star.
C) Its spectrum will show large amounts of hydrogen.
D) Its core was mostly iron.
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E) The star never reached the Chandrasekhar limit.
Which statement about dark dust clouds is true?
A) Hydrogen and helium are the chief absorbing and scattering agents.
B) They block the vast majority of radio waves from our Galaxy.
C) They can be penetrated only with longer wavelengths such as radio and infrared.
D) They comprise the majority of the mass of the Galaxy.
E) They can be penetrated only with shorter waves, such as UV and X-ray.
This diagram explains
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A) the difference between solar time and sidereal time.
B) precession.
C) the solar day's relation to the Moon.
D) the sidereal day's relation to the seasons.
E) the reason for the solstices.
The next moon likely to be broken up into a ring is ________.
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Contrast Irr I and II in terms of structure.
As with the lunar mare and Earth's ocean basins, the chief rock in the low plains of
Venus is ________.
Explain how Bohr's model creates emission and absorption lines in the spectrum.
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While Saturn is almost as large as Jupiter, its mass is only about ________ of Jupiter's.
According to Newton, the gravity of the ________ is needed to explain planetary orbits.
Will Mars ever appear to the unaided eye as large as the Moon at closest approach?
Explain.
The Great Nebula in Orion, M-42, is a low-density cloud of hot gas. Use Kirchhoff's
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laws to describe its spectrum.
On the H-R diagram, a star's position on the main sequence depends on the star's
________.
How did the discovery of pulsars by Jocelyn Bell lead to the winning of a Nobel Prize
by Anthony Hewish?
What three properties describe a black hole?
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As we go outward from Io to Ganymede, the density of the moons ________.
A moon whose surface is smooth, with no craters, is probably ________.
The Sun and stars rise in the east, and set in the west. Contrast ancient and modern
explanations for this observation.
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Most pulsars emit ________.
Our solar system lies in the galaxy's ________, about 30,000 light years from the
Galactic Center.
Describe the Cassini mission to Saturn in 2004-5.
Some giant elliptical galaxies are found to have disks of gas and dust with star forming
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regions, and are probably the result of ________.
Counting only the material between us and the galactic Center, we measure a mass of
________ billion Suns.
What color are most of the stars closest to the Sun?

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