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Astronomy Test 3
Terms in this set (49)
why do sunspots appear darker?
they have lower temperatures
what ionizes gas in a planetary nebula and make it visible?
ultraviolet photons emitted by a stellar core
what can we use to determine how the density changes with radius in the sun?
a star less than 8 solar masses will end up as what?
carbon/oxygen white dwarfs
why does a white dwarf reach the Chandrasekhar mass and explode in a type 1a supernova?
there is runway thermonuclear fusion of hydrogen on the surface, and the hydrogen does not have time to cool burns to carbon and oxygen nondegenerately
what are neutron stars supported by?
which galaxies have a bar like structure in them?
if the sun was replaced by a black hole, what would the difference be on the gravitational pull on the earth?
it would be the same as it is now
what halts the low mass main sequence stars climb to the red giant branch?
the beginning of helium fusion in the core
what are he result of pulsars?
the rotation of a neutron star with a strong magnetic field
what does the hubble constant represent?
the rate of expansion of the universe
according to hubble's law, the distance of the galaxy is___ and its ___ is increases
increases, recessional velocity
what characteristic clearly separates elliptical galaxies from spiral galaxies?
where does the energy from solar activity come from?
the collapse of the core of a high mass star at the end of its life is approximately how long?
what does the equivalence principle say?
being stationary in a gravitational field is the same as being in an accelerated reference frame
what does the collapsar model explain?
the formation of gamma ray bursters
if you measure the average brightness of the pulsation period of a Cephid variable star, you can determine what else?
what does Einsteins theory of general relativity tell us?
a photons paths through space time are curved in the presence of a massive body
what are the bulk of neutron stars made of?
neutrons with some protons and electrons
what is the most likely dark matter candidate?
what are neutron stars produced by?
core collapse of iron core of a massive star
if helium burns in the core of a horizontal branch star via ___ it produces what?
triple alpha reaction, carbon and oxygen
where is most of the luminosity from the sun emitted from?
what does a high mass star create energy with on the main sequence?
the CNO cycle
what is the maximum mass of a white dwarf?
1.4 mass, the Chandrasekhar mass
what is the result of distorting the fabric of spacetime?
if you observe a supernova spectra with no balmer lines, but has a strong silicon line with absorption line, what are you seeing?
type 1a supernova
what do you see if you observe a spectrum with strong balmer lines?
what is the maximum of a neutron star?
the Chandrasekhar mass, 1.4 solar masses
which star spends the least time as a main sequence star?
the one with the most mass
how does the sun create energy on the main sequence?
the p p cycle
why do novae occur?
runway thermonuclear fusion of hydrogen on the surface, so the hydrogen has time to cool and is supported by quantum mechanical pressure of electrons
what does the hubble tuning fork illustrate?
why do AGB stars have high mass loss rates?
they have strong winds
where is nearly all the carbon in the universe created?
core collapse supernovae
what are white dwarfs supported by?
quantum mechanical pressure of relativistic electrons
what is the property of a star that determines its density?
what is the radius of the event horizon of a 10 solar mass black hole?
why can an iron core not support a massive main sequence star?
it cannot fuse with another nuclei to produce energy
what is the solar cycle a result of?
convection and the winding up of the solar magnetic field
when do stars reach the zero age main sequence?
they start burning hydrogen in their cores
what is the event horizon of a black hole?
the radius at which the escape speed equals the speed of light
what does the detection of solar neutrinos confirm?
that the suns core is powered by proton proton fusion
when is hawking radiation emitted from a black hole?
a virtual pair of particles is created from the vacuum of space
when do stars leave the main sequence?
they run out of hydrogen in their cores
what do astronomers use galactic redshift as?
what did Edwin hubble study that proved there were other galaxies out there?
why can type 1a supernovae be used to determine a galaxies distance?
all type 1a supernovae have approximately the same luminosity
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