Chapter 9 Astronomy – Flashcards
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What slows down the contraction of a star-forming cloud when it makes a protostar?
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trapping of thermal energy inside the protostar
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Which of these stars has the hottest core?
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a white main-sequence star
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Which of these stars does not have fusion occurring in its core?
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a red giant
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What happens to a low mass star after a helium flash?
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Its luminosity goes down.
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What would stars be like if hydrogen had the smallest mass per nuclear particle?
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Nuclear fusion would not occur in stars of any mass
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What would stars be like if carbon had the smallest mass per nuclear particle?
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Supernovae would be more common
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What would you be most likely to find if you returned to the solar system in 10 billion years?
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The Sun would be a white dwarf.
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in which of the following objects does degeneracy pressure fail to stop gravitational contraction
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the core of a high-mass star
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what happens to the core of a high-mass star after it runs out of hydrogen?
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it shrinks and heats up
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which of these star clusters is youngest
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a cluster containing stars of all colors
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which of these star clusters is oldest
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a cluster whose brightest main-sequence stars are yellow
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Which of the following changes would cause the fusion rate in the Sun's core to increase?
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An increase in the core temperature increases the fusion rate because the fusion rate is very sensitive to temperature. A decrease in the core radius causes the core to heat up and increase in density, which therefore leads to an increased fusion rate.
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Which of the following must occur for a star's core to reach equilibrium after an initial change in fusion rate?
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If the fusion rate initially increases, then the core expands.
If the fusion rate initially decreases, then the core contracts
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What would happen if the fusion rate in the core of the Sun were increased but the core could not expand?
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The Sun's core would start to heat up and the rate of fusion would increase even more.
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Mass of all the planets
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The total mass of all the planets is approximately 3×10^27 kg, which is roughly 500 times the mass of the Earth.
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layers of the sun
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The lowest layer of the sun's atmosphere is the photosphere. (coolest) then chromosphere which emits a reddish glow as super-heated hydrogen burns off. But the red rim can only be seen during a total solar eclipse. The third layer of the sun's atmosphere is the corona.
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temperature scale
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O-B-A-F-G-K-M, and that it corresponds to a temperature scale
with O stars being the hottest at ~ 30,000 K and hotter, and M stars the coolest at ~ 3000K and
below.
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conditions under which stars form
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involving very low temperatures in
massive molecular clouds
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Understand the two types of equilibrium (or balance) that are present in all main sequence
stars.
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gravitational contraction and gravitational equilibrium
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Understand how the mass of a main sequence star determines its core temperature and
luminosity
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stars less massive than the sun come into balances with a cooler core temperature, lower luminosity, and smaller radius.
stars more massive than the sun come into balance with hotter temp, greater luminosity, and a larger radius.
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life of a low mass ( < 8 x solar mass) star
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protostar, yellow main sequence star, red giant, helium core fusion star, double shell fusion red giant, planetary nebula, white dwarf
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life of a high mass star
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protostar, blue main sequence star, red supergiant, helium core fusion, multiple shell fusion supergiant, supernova, neutron star or black whole.
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star clusters
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globular and open.
Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain fewer than a few hundred members, and are often very young.
