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What makes the subject of star formation so difficult and complex?
A) Shock waves disrupt the orderly evolution of stars.
B) Stars live too long to be observed from birth to death.
C) It is so slow that no visible proof of it exists.
D) Star formation is too expensive to study in detail.
E) Clouds, fragments, protostars, stars, and nebulae all interact and influence each other. |
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Which statement about the stages of starbirth is false?
A) By stage 7, the star has reached the main sequence.
B) By stage 3, the star has formed a photosphere.
C) The T-Tauri wind is prevalent in stage 5.
D) Nuclear reactions begin in the core by stage 4.
E) At stage 1, only the cloud exists. |
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In the collapsing cloud fragment stage (stage 2) of star formation, the size of the cloud fragment is about
A) the size of the Solar System.
B) 10 times the size of the Solar System.
C) 100 times the size of the Solar System.
D) 1/10th the size of the Solar System.
E) 1000 times the size of the Solar System. |
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Stage 4 of star formation is when the object can exhibit violent surface activity producing extremely strong protostellar winds. This phase is also called the
A) T-Tauri phase
B) protostar phase
C) protoplanetary nebula phase
D) Herbig-Haro phase
E) brown dwarf phase |
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What is the critical temperature at which hydrogen can fuse into helium in the star's core?
A) 100 million K
B) 26,000 K
C) 5,800 K
D) ten million K
E) one million K |
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If the initial interstellar cloud in star formation has a mass sufficient to form hundreds of stars, how does a single star form from it?
A) One star forms at its center and blows the rest of the matter back into space.
B) One star forms and the rest of the matter goes into making planets, moons, and other objects of a solar system.
C) The cloud is disrupted by rotation so that it reduces its mass down to that of a typical star.
D) The cloud fragments into smaller clouds and forms many stars at one time.
E) A supernova blows the cloud up and dissipates the majority of the gas. |
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At what stage of evolution do T Tauri stars occur?
A) after the star has established itself as a main sequence star
B) just prior to the protostar stage
C) when a protostar is on the verge of becoming a main sequence star
D) just as the collapsing cloud becomes luminous
E) just after the planetary nebula is expelled |
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A star spends most of its life:
A) as a main sequence star.
B) as a planetary nebula.
C) as a T Tauri variable star.
D) as a red giant or supergiant.
E) as a protostar. |
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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) black hole.
D) nova.
E) white dwarf. |
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What is a typical age for a globular cluster?
A) 12 billion years
B) 4.8 billion years
C) 200 million years
D) 10 million years
E) one billion years |
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What spectral type of star that is still around (not in a binary system) formed most recently?
A) M
B) F
C) A
D) O
E) K |
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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) The core contracts, raising the core temperature and increasing the size of the shell of hydrogen burning.
C) Its outer envelope is stripped away and we see the brilliant core.
D) It immediately starts to fuse helium.
E) It explodes. |
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Which of these will the Sun probably become in the very distant future?
A) hypernova
B) nova
C) supernova
D) planetary nebula
E) pulsar |
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What characteristic of a star cluster is used to determine its age?
A) the ratio of main sequence to white dwarfs stars
B) the number of red giants
C) the total number of stars in the cluster
D) the main sequence turnoff
E) the faintest stars seen in the cluster |
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A surface explosion on a white dwarf, caused by falling matter from the atmosphere of its binary companion, creates what kind of object?
A) hypernova
B) type II supernova
C) type I supernova
D) nova
E) gamma ray burstar |
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What evidence is there that supernovae really have occurred?
A) existence of heavy radioactive elements in nature
B) supernova remnants
C) All of the answer choices are correct
D) observations of the actual explosions
E) Crab Nebula |
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Which of these is the likely progenitor of a type I supernova?
A) an evolved blue supergiant that is about to experience the helium flash
B) a helium-neon white dwarf
C) a contact binary, with the neutron star at 2.3 solar masses
D) a mass-transfer binary, with the white dwarf already at 1.3 solar masses
E) an evolved red giant which is just starting to make silicon in its core |
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Most of the energy of the supernova is carried outward via a flood of:
A) neutrinos.
B) gamma rays.
C) protons.
D) helium nuclei.
E) positrons. |
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The making of abundant iron nuclei is typical of:
A) the helium flash.
B) type I supernovae.
C) type II supernovae.
D) planetary nebula ejection.
E) all novae. |
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What is stellar nucleosynthesis?
A) The formation of heavier elements inside stars.
B) The formation of planetary nebulae by red giants.
C) The formation of stars from a nucleus of contracting material.
D) The process by which stars form interstellar dust.
E) The formation of white dwarfs, neutron stars, and black holes from stars. |
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An iron core cannot support a star because:
A) iron supplies too much pressure.
B) iron is the heaviest element, and sinks upon differentiation.
C) iron has poor nuclear binding energy.
D) iron cannot fuse with other nuclei to produce energy.
E) iron is in the form of a gas, not a solid, in the center of a star. |
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The supernova of 1054 AD produced:
A) a remnant still visible to the naked eye, the Crab Nebula, M-1.
B) the most famous black hole.
C) the closest known neutron star to our Sun.
D) no remaining visible trace, as it was a type I supernova.
E) a pulsar with a period of 33 milliseconds, visible optically. |
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X-ray bursters occur in binary star systems. The two types of stars that must be present to make up such an object are:
A) a white dwarf and a main sequence star.
B) two neutron stars in a mass transfer binary.
C) a white dwarf and a neutron star.
D) a main sequence or giant star and a neutron star in a mass transfer binary.
E) a contact binary system of two red giants. |
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A proposed explanation for gamma-ray bursters is
A) hypernova-making black holes and bi-polar jets.
B) collisions between two white dwarfs
C) coalescence of a neutron star binary.
D) All of the answer choices are possible explanations. |
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Neutron stars have
A) monopolar fields that switch polarity every rotation.
B) very strong bi-polar magnetic fields.
C) no relation to pulsars.
D) weak or non-existent magnetic fields.
E) periods of days or weeks. |
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Which of the following can actually escape from inside a black hole's event horizon?
A) electrons
B) Nothing can escape from inside a black hole's event horizon.
C) gravitons
D) neutrinos
E) very high energy gamma-rays |
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Almost half of all known millisecond pulsars are found in what type of object?
A) supernova remnants
B) emission nebulae
C) giant molecular clouds
D) open clusters
E) globular clusters |
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What is the name of the most famous black hole candidate?
A) Cygnus X-1
B) Scorpio X-1
C) Betelguese
D) Sagittarius A
E) Centaurus A |
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