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The masses of stars on the main sequence __________ from the lower right to the upper left.
increase
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The fundamental quantity which determines a star's central pressure and temperature is its
mass.
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The Russell-Vogt theorem (about chemical composition) states that the properties of a star at any given age depend completely upon the star's
mass and chemical composition.
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The lifetime of a star is determined by its initial
mass and luminosity.
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Stars evolve because of changes in
chemical composition of the core.
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The triple alpha reaction converts _________ into __________.
c. helium, carbon
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A nuclear reaction which occurs at sometime after hydrogen is exhausted in the core is the
triple alpha reaction.
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The temperature of a star's core will __________ as the star fuses heavier elements.
. increase
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The evolution of a star depends primarily on the star's
mass.
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Stars on the upper end of the main sequence next evolve into
red giants.
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A T Tauri star is one which is
variable and shedding mass.
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Protostars in dark, dusty regions may be studied in the __________ spectral region.
d. infrared
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During the formation of a star, the contraction stops when
c. hydrogen burning becomes the dominant energy source.
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Hydrogen burning for a Sun-like star lasts approximately
ten billion years.
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What types of stars are found on the zero-age main sequence
newly formed stars
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When the hydrogen in the core of a star has been converted to helium, the core will next
contract.
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Which of the following occurs during and immediately after the phase of the hydrogen burning shell?
the envelope expands and cools, and the star becomes a red giant
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As a degenerate gas is heated, it will
neither expand nor contract.
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The ignition of helium in the degenerate core of a one solar mass star produces
a helium flash.
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In a degenerate electron gas the outward pressure which keeps the star from collapsing is
independent of temperature.
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Which of the following is NOT a characteristic of a red giant?
cool core
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The horizontal branch is
a helium core surrounded by a hydrogen burning shell.
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A planetary nebula is
an expanding gas cloud that was ejected by a star.
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The stellar remnant of a one solar mass star is a
white dwarf.
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High mass stars evolve more rapidly than low mass ones because the high mass stars
b. have higher core temperatures.
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In the most massive stars, the heaviest element which will be produced in the core will be
iron.
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Each time a form of nuclear fuel is exhausted in the core of a star, the star
returns to the red giant branch
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The most mass a white dwarf can have is about
1.4 Solar Mass.
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What element is observed in the spectra of Type II supernova?
hydrogen
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A star which has a main sequence mass of 10 solar masses will most likely end up as
a T Tauri star.
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If a neutron star has more mass than its mass limit, it will
contract catastrophically.
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A black hole is called that because
c. photons can not be emitted from it.
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A neutron star's size is that of
a typical city.
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The most massive stars are thought to end up as
black holes.
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Heavy elements which are mixed into the material from which new generations of stars may come primarily from
supernovae
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After the initial outburst of Supernova 1987A had diminished, the main source of luminosity was energy released from
radioactive decay.
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What was the most energetic component of Supernova 1987A?
the energy released in neutrinos
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Which of the following objects would have the highest gravitational redshift?
a black hole
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A white dwarf will cool to become a black dwarf in several
billion years.
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White dwarfs are composed mostly of
degenerate gases.
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All novae are thought to involve a
white dwarf.
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Novae explosions are caused by
d. mass lost from a normal star falling onto a white dwarf companion.
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How can astronomers determine which type of supernovae they are observing?
the spectral features are different
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The internal properties of a neutron star are most similar to those of a __________ star
white dwarf
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Stellar remnants with masses between 2 and 3 solar masses will be
neutron stars
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Pulsars are known to be
d. rotating neutron stars.
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Binary X-ray sources are known to be binary because
eclipses are observed.
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The accretion disk surrounding a neutron star is very hot due to compression caused by gravitational forces. This implies the object will emit strongly in which spectral region?
X ray
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If the Sun were suddenly to be replaced by a solar-mass black hole the gravitational force on the Earth (1 A. U. away) would
remain the same.
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The Schwarzschild radius of a black hole is
b. the distance from a black hole inside of which light cannot escape.
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From the outsider's point of view, in watching a star collapse to form a black hole, the collapse would appear to take
forever.
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Which of the following lists the stellar remnants in order of decreasing maximum mass?
black hole, neutron star, white dwarf
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A black hole is really
strongly curved space.
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How is it possible to detect the presence of a black hole?
. by its effect upon other objects around it
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