alah – Flashcard
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For a star of Sun-like mass, what is the last stage of the nuclear fusion?
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helium to carbon and oxygen
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The sun will eventually become a supernova.
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False
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A nova destroys the star and leaves behind a white dwarf.
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false
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____ is a form of electromagnetic radiation produced by rapidly moving electrons spiraling through magnetic fields.
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Synchrotron radiation
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In degenerate matter
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pressure does not depend on temperature
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Even in degenerate matter, pressure depends on temperature.
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False
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After what evolutionary stage does a star become a white dwarf?
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Giant
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A mass is transferred in a normal star in a binary system toward a white dwarf, the material forms a rapidly growing whirlpool of material known as aNo
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accretion disk
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A white dwarf is composed of
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carbon and oxygen nuclei and degenerate electrons
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No known white dwarf has a mass greater than the Chandrasekhar limit.
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True
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A star begins fusing hydrogen to helium the moment it leaves the main sequence.
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False
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The Chandrasekhar limit tells us that
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white dwarfs more massive than 1.4 solar masses are not stable
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Giant and supergiant stars are rare because
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the giant or supergiant stage is very short
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The average size of a white dwarf is about the same size as the Earth.
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True
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What are the two longest stages in the life of a one solar mass star?
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main sequence, white dwarf
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A Type II supernova produces a planetary nebula.
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False
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Stars in a star cluster
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a. all have the same age. b. all have the same chemical composition.
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The explosion of a supernova typically leaves behind
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a shell of hot, expanding gas with a pulsar at the center
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Because more massive stars have more gravitational energy, they can fuse heavier nuclear fuels.
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True
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Stars that have ejected a planetary nebula eventually become
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white dwarfs
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Once a star ejects a planetary nebula, it becomes a white dwarf.
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True
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Synchrotron radiation is produced by
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high-velocity electrons moving through a magnetic field.
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Type II supernovae are believed to occur when the cores of massive stars collapse.
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True
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A Type I supernova is believed to occur when
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a white dwarf exceeds the Chandrasekhar limit
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A planetary nebula is
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the expelled outer envelope of a medium mass star
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Where are elements heavier than iron primarily produced?
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Supernovae
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A nova is almost always associated with
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a white dwarf in a close binary system
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The Crab nebula is
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supernova remnant.
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Helium fusion does not begin until the star has entered the giant region of the H-R diagram.
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True
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As a main sequence star exhausts hydrogen in its core, it next becomes
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a red giant star.
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Star clusters are important to our study of stars because
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they give us a method to test the our theories and models of stellar evolution
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Giant and supergiant stars are rare because that stage of stellar evolution is short.
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True
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Massive stars cannot generate energy through iron fusion because
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both fusion or fission of iron nuclei absorb energy
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The theory that the collapse of a massive stars iron core produces neutrinos was supported by
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the detection of neutrinos from the supernova of 1987
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Planetary nebulae are sites of planet formation.
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False
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Stars swell into giants when hydrogen is exhausted in their centers.
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True
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Which of the following nuclear fuels does a one-solar mass star use over the course of its entire evolution?
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hydrogen and helium
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Stars within a cluster that are at the turnoff point
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have life expectancies that are equal to the age of the cluster
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As a white dwarf cools its radius will not change because
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pressure does not depend on temperature for a white dwarf because the electrons are degenerate
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If the theory that novae occur in close binary systems is correct, then novae should
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repeat after some interval
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Stars less massive than 0.4 solar mass never become giant stars.
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True
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Synchrotron radiation is produced
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in supernova remnants.
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The Algol paradox is explained by considering
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mass transfer between the two stars in a binary system
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A Type Ia supernova is believed to occur when
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a white dwarf in a binary system exceeds the Chandrasekhar limit.
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Helium flash occurs
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because degenerate electrons in the core do not allow the core to expand as it heats up
