question

Which is the least dense? A. interstellar gas B. interstellar dust C. the atmosphere of Earth D. the atmosphere of Jupiter E. the atmosphere of the Sun

answer

B. interstellar dust

question

Most interstellar clouds are A. much bigger than our solar system. B. about the size of Earth. C. similar in size to clouds in Earth's atmosphere. D. much smaller than the clouds in Earth's atmosphere. E. about the size of a wavelength of light.

answer

A. much bigger than our solar system.

question

Emission nebulae like M42 occur only near stars that emit large amounts of A. visible light. B. microwaves. C. ultraviolet radiation D. infrared heat. E. x-rays and gamma rays.

answer

C. ultraviolet radiation

question

What is the primary visible color of an emission nebula? A. black, because of dust B. blue from the scattering of light off the tiny molecules C. blue due to ionized helium atoms D. red due to ionized hydrogen atoms E. red because of reddening by dust

answer

D. red due to ionized hydrogen atoms

question

In which wavelengths have the births of new stars been best mapped recently? A. gamma rays B. extreme ultraviolet C. infrared D. microwave E. radio

answer

C. infrared

question

What two things are needed to create an emission nebulae? A. interstellar gas and dust B. hydrogen fusion and helium ionization C. cool stars and much interstellar dust D. hot stars and interstellar gas, particularly hydrogen E. hydrogen gas and carbon dust

answer

D. hot stars and interstellar gas, particularly hydrogen

question

Which of these is not a consequence of dust in the interstellar medium? A. reddening of stars' light that passes through the dust B. blue reflection nebulae around the Pleiades C. red light from the emission nebulae D. the dark nebulae that block 90% of the Milky Way from us visually E. terrestrial planets like our own

answer

C. red light from the emission nebulae

question

A reflection nebula is caused by A. starlight reflected off of a surface. B. sunlight reflected off of a surface. C. sunlight scattered by dust particles. D. starlight scattered by dust particles. E. emission by ionized gas.

answer

D. starlight scattered by dust particles.

question

What information does 21 cm radiation provide about the gas clouds? A. their motion B. their distribution C. their density D. their temperature E. all of these

answer

E. all of these

question

What is the key factor that determines the temperature, density, radius, luminosity, and pace of evolution of a protostellar object? A. composition of the nebula B. rotation of the nebula C. mass of the nebula D. temperature of the nebula E. magnetism of the nebula

answer

C. mass of the nebula

question

Which is characteristic of globular star clusters? A. old age and hundreds of thousands of stars, only about 30 ly wide B. no remaining MS stars, but millions of white dwarfs C. only brown dwarfs in a yellow ball 100 ly across D. bright blue main sequence stars, and thousands of them E. a mix of old and young stars, about 100,000 ly across

answer

A. old age and hundreds of thousands of stars, only about 30 ly wide

question

A collapsing cloud fragment that will form a star of one solar mass (like our Sun) has a mass of about A. 2 solar masses. B. 10 solar masses C. 200 solar masses. D. 1020 solar masses. E. 1040 solar masses.

answer

A. 2 solar masses

question

Stars form from a collapsing cloud that fragments into smaller and smaller pieces. This process takes about A. 10,000 years. B. 25,000 years. C. 100,000 years. D. a few million years. E. 100 million years

answer

D. a few million years.

question

Most stars in our part of the Galaxy are formed A. alone. B. in open clusters of a few dozen. C. in associations of thousands of stars across a spiral arm of the Galaxy. D. in globular clusters of millions of stars. E. in a singular event just after the Big Bang

answer

B. in open clusters of a few dozen.

question

At what stage of evolution do T Tauri stars occur? A. just as the collapsing cloud becomes luminous B. when a protostar is on the verge of becoming a main sequence star C. just prior to the protostar stage D. just after the planetary nebula is expelled E. after the star has established itself as a main sequence star

answer

B. when a protostar is on the verge of becoming a main sequence star

question

A cloud fragment too small to form a star becomes: A. a red giant. B. a black hole. C. a brown dwarf D. a T Tauri object. E. a Herbig Haro object

answer

C. a brown dwarf

question

On an H-R diagram, a protostar would be A. above and to the right of the main sequence. B. below and to the left of the main sequence. C. below and near the right side of the main sequence. D. above and near the upper left of the main sequence. E. on the main sequence at the extreme lower right.

answer

A. above and to the right of the main sequence.

question

At which stage in a sun-like star's life is its core the least dense? A. Main Sequence B. Subgiant Branch C. Helium Fusion D. Planetary Nebula E. White Dwarf

answer

A. Main Sequence

question

What temperature is needed to fuse helium into carbon? A. 5,800 K B. 100,000 K C. 15 million K D. 100 million K E. one billion K

answer

D. 100 million K

question

A star is on the horizontal branch of the H-R diagram. Which statement is true? A. It is burning both hydrogen and helium. B. It is about to experience the helium flash. C. It is burning only helium. D. The star is contracting. E. The star is about to return to the main sequence.

answer

A. It is burning both hydrogen and helium.

question

What inevitably forces a star like the Sun to evolve away from being a main sequence star? A. The core begins fusing iron. B. The star uses up all its supply of hydrogen. C. The carbon detonation explodes it as a type I supernova. D. Helium builds up in the core, while the hydrogen burning shell expands. E. The core loses all its neutrinos, so all fusion ceases.

answer

D. Helium builds up in the core, while the hydrogen burning shell expands.

question

Just as a low-mass main sequence star runs out of fuel in its core, it actually becomes brighter. How is this possible? A. Helium fusion gives more energy than hydrogen fusion does, based on masses. B. Its outer envelope is stripped away and we see the brilliant core. C. The core contracts, raising the temperature and increasing the size of the region of hydrogen shell-burning. D. It explodes. E. It immediately starts to fuse helium.

answer

C. The core contracts, raising the temperature and increasing the size of the region of hydrogen shell-burning.

question

What is a planetary nebula? A. the bipolar jets ejected by a T Tauri variable B. a planet surrounded by a glowing shell of gas C. the disc of gas and dust surrounding a young star that will soon form a solar system D. the ejected envelope, often bipolar, of a red giant surrounding a stellar core remnant E. a type of young, medium mass star

answer

D. the ejected envelope, often bipolar, of a red giant surrounding a stellar core remnant

question

What are black dwarfs? A. the lowest mass main sequence stars B. the end result of massive star evolution C. objects that are not quite massive enough to be stars D. pulsars that have slowed down and stopped spinning E. cooled off white dwarfs that no longer glow visibly

answer

E. cooled off white dwarfs that no longer glow visibly

question

The order of evolutionary stages of a star like the Sun would be Main Sequence, giant, planetary nebula, and finally: A. hypernova. B. neutron star. C. white dwarf. D. nova. E. black hole.

answer

C. white dwarf

question

Compared to our Sun, a typical white dwarf has A. about the same mass and density. B. about the same mass and a million times higher density. C. a larger mass and a 100 times lower density. D. a smaller mass and and half the density. E. a smaller mass and twice the density.

answer

B. about the same mass and a million times higher density.

question

Refer to the figure above. What is the name of the path between the points labeled 11 and 12? A. planetary nebula B. red giant branch C. horizontal branch D. asymptotic giant branch E. white dwarf

answer

A. planetary nebula

question

An iron core cannot support a star because A. iron is the heaviest element, and sinks upon differentiation. B. iron has poor nuclear binding energy. C. iron cannot fuse with other nuclei to produce energy. D. iron supplies too much pressure. E. iron is in the form of a gas, not a solid, in the center of a star.

answer

C. iron cannot fuse with other nuclei to produce energy

question

Most of the energy of the supernova is carried outward via a flood of A. gamma rays. B. helium nuclei. C. protons. D. neutrinos. E. positrons.

answer

D. neutrinos.

question

In neutronization of the core, a proton and an electron make a neutron and a A. positron. B. muon. C. neutrino. D. pion. E. antineutron.

answer

C. neutrino.

question

As a star's evolution approaches the Type II supernova, we find A. the heavier the element, the less time it takes to make it. B. the heavier the element, the higher the temperature to fuse it. C. helium to carbon fusion takes at least 100 million K to start. D. photodisintegration of iron nuclei begins at 10 billion K to ignite the supernova. E. All of these are correct.

answer

E. All of these are correct.

question

What made supernova 1987a so useful to study? A. We saw direct evidence of nickel to iron decay in its light curve. B. Its progenitor had been observed previously. C. In the Large Magellanic Cloud, we already knew its distance. D. It occurred after new telescopes, such as Hubble, could observe it very closely. E. All of these are correct.

answer

E. All of these are correct.

question

Where was supernova 1987a located? A. in the Orion Nebula, M-42 B. in Sagittarius, near the Galactic Nucleus C. in our companion galaxy, the Large Magellanic Cloud D. in M-13, one of the closest of the evolved globular clusters E. near the core of M-31, the Andromeda Galaxy

answer

C. in our companion galaxy, the Large Magellanic Cloud

question

What produces a type-I supernova? A. the collapse of the core of a massive star B. the helium flash blows apart a giant's core C. mass transfer onto a white dwarf pushing it over 1.4 solar masses D. a nova igniting a helium flash in its red giant companion E. the radioactive decay of nickel 56 into cobalt 56 into iron 56

answer

C. mass transfer onto a white dwarf pushing it over 1.4 solar masses

question

Which of these is the likely progenitor of a type I supernova? A. a mass-transfer binary, with the white dwarf already at 1.3 solar masses B. a contact binary, with the neutron star at 2.3 solar masses C. an evolved red giant which is just starting to make silicon in its core D. an evolved blue supergiant that is about to experience the helium flash E. a helium-neon white dwarf

answer

A. a mass-transfer binary, with the white dwarf already at 1.3 solar masses

question

What would happen if mass is added to a 1.4 solar mass white dwarf? A. The star would explode as a nova. B. The star's radius would increase. C. The star would immediately collapse into a black hole. D. The star would erupt as a carbon detonation (type I) supernova. E. The core would collapse as a type II supernova.

answer

D. The star would erupt as a carbon detonation (type I) supernova.

question

Neutron stars do not have A. masses greater than 1.4 solar masses. B. sizes comparable to large cities. C. strong magnetic fields. D. large surface gravities, compared to the Sun. E. rotation periods comparable to the Sun's.

answer

E. rotation periods comparable to the Sun's.

question

Which of these does not exist? A. a million solar mass black hole B. a 6 solar mass black hole C. a 6.8 solar mass neutron star D. a 1.0 solar mass white dwarf E. a 0.06 solar mass brown dwarf

answer

C. a 6.8 solar mass neutron star

question

What compelling evidence links pulsars to neutron stars? A. Both pulsars and neutron stars can be found in globular star clusters. B. Pulsars are known to evolve into neutron stars. C. Only a small, very dense source could rotate that rapidly without flying apart. D. Pulsars are always found in binary systems with neutron stars. E. Both pulsars and neutron stars have been discovered near the Sun.

answer

C. Only a small, very dense source could rotate that rapidly without flying apart.

question

You would expect millisecond pulsars to be A. part of a binary system. B. isolated in space. C. rotating slowly. D. most common in open clusters. E. collapsing rapidly.

answer

A. part of a binary system.

question

Which of the following can actually escape from inside a black hole's event horizon? A. neutrinos B. electrons C. very high energy gamma-rays D. gravitons E. none of these

answer

E. none of these

question

The mass range for neutron stars is A. .08 to .4 solar masses. B. .4 to 3 solar masses. C. 1.4 to 3 solar masses. D. 3 to 8 solar masses. E. 6 to 11 solar masses

answer

C. 1.4 to 3 solar masses.

question

When mass is accreted into a black hole, how much total mass-energy can be radiated away? A. .007% B. .08% C. 1.4% D. 20% E. 50%

answer

D. 20%

question

Which of the following is true about the ages and masses of spiral and elliptical galaxies? A. Ellipticals are all older and more massive than spirals. B. Spirals are older, and much more massive than ellipticals. C. Both types are about the same age, but spirals vary less in mass. D. Spirals are younger and much more massive than any elliptical. E. Ellipticals are older, and show a far wider range of masses than do spirals.

answer

C. Both types are about the same age, but spirals vary less in mass.

question

What is the nearest huge cluster of galaxies to our Local Group? A. Coma Cluster B. Centaurus Cluster C. Virgo Cluster D. Orion Nebula E. Hercules Cluster

answer

C. Virgo Cluster

question

The Tully-Fisher relation exists between the galaxy's luminosity and its A. color. B. age. C. rotation D. mass. E. size.

answer

C. rotation

question

Which statement about the Local Group is false? A. It contains about 45 member galaxies. B. Its notable spirals include the Milky Way, M31, and M33. C. Most of its members are dwarf elliptical and irregular galaxies. D. It contains the large radio galaxy Centaurus A. E. It is about three million light years across.

answer

D. It contains the large radio galaxy Centaurus A.

question

Why does the Cepheid "standard candle" have limited usefulness beyond 20 Mpc? A. Distant galaxies are seen in the past, when Cepheid variables behaved differently than they do today. B. Distant galaxies are so young they do not contain Cepheids. C. Cepheids are too faint to be seen beyond that distance, even with HST. D. The light variability of Cepheids diminishes with distance so they do not appear to vary there. E. Older distant Cepheids are of population II, where the period-luminosity relation no longer works.

answer

C. Cepheids are too faint to be seen beyond that distance, even with HST.

question

Which of the following paraphrases Hubble Law? A. The faster the galaxy spins, the more massive and luminous it is. B. The greater the distance to a galaxy, the greater its redshift. C. The greater the distance to a galaxy, the fainter it is. D. The more distant a galaxy is, the younger it appears. E. The older the galaxy appears to us, the more luminous it is.

answer

B. The greater the distance to a galaxy, the greater its redshift.

question

According to the Hubble Law, a galaxy with a velocity of 25,000 km/s will be A. 100 million pcs away. B. 400 million pcs away. C. 700 million pcs away. D. 1000 million pcs away. E. less than 1 million pcs away.

answer

B. 400 million pcs away.

question

Quasars usually have their distances measured by what technique? A. Type II supernovae B. Cepheids C. Parallax D. Hubble's Law E. Tully-Fisher relation

answer

D. Hubble's Law

question

Based on galactic rotation curves and cluster dynamics, we think dark matter A. is a minor component of the entire mass of the universe. B. is best detected from the x-rays it produces in the intergalactic medium. C. will have no effect on the fate of the universe. D. comprises over 90% of the entire mass of the universe. E. will doom the universe to collapse, overcoming the red shifts we now observe.

answer

D. comprises over 90% of the entire mass of the universe.

question

Collisions between galaxies is thought to A. have stopped about 5 billion years ago. B. be commonplace. C. have never occurred. D. be extremely rare. E. have only occurred between 10 and 15 billion years ago.

answer

B. be commonplace.

question

Compared to the Milky Way, how many stars are contained in the most massive galaxies? A. two-three times B. tens of times C. hundreds of times D. thousands of times E. millions of times

answer

B. tens of times

question

The distance between adjacent galaxies in a typical cluster is about ________ times the size of a typical galaxy. A. two or three B. five or less C. ten to twenty D. a hundred E. a thousand

answer

B. five or less

question

Astronomer's believe that a spiral galaxy may form A. from a collision between a small and large galaxy. B. due to a quasar shutting down. C. from the sudden contraction of an elliptical galaxy. D. from the collision of two giant elliptical galaxies E. from the explosion of a dwarf irregular galaxy.

answer

A. from a collision between a small and large galaxy.

question

Some quasars show absorption spectra with a smaller redshift than their emission spectra, this indicates that A. we still don't understand redshifts. B. they are much closer than previously thought. C. there is cooler gas between us and the quasar. D. their black holes are still contracting. E. their black holes are still expanding.

answer

C. there is cooler gas between us and the quasar.

question

For finding the distance to M31, Hubble relied upon A. RR Lyrae stars in its globular clusters. B. Type I supernova in its core. C. Type II supernova in its spiral arms. D. Cepheid variables in its spiral arms. E. planetary nebulae near its core.

answer

D. Cepheid variables in its spiral arms.

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