Module 9 Astronomy

24 July 2022
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question
he temperature in the core of main sequence stars gradually rises. How does this affect the hydrogen fusion rate of the star?
answer
The rate of fusion increases
question
What happens when a star exhausts its core hydrogen supply?
answer
Its core contracts, but its outer layers expand and the star becomes brighter and brighter.
question
What is happening inside a star while it expands into a subgiant?
answer
It is fusing hydrogen into helium in the core
question
Compared to the star it evolved from a red giant is
answer
cooler and brighter
question
At approximately what temperature can helium fusion occur?
answer
100 million K
question
Why does a star grow larger after it exhausts its core hydrogen?
answer
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.
question
How many helium nuclei fuse together when making carbon?
answer
3
question
What is a planetary nebula?
answer
the expanding shell of gas that is no longer gravitationally held to the remnant of a low-mass star
question
What happens to the core of a star after a planetary nebula occurs?
answer
It becomes a white dwarf
question
Which of the following sequences correctly describes the stages of life for a low-mass star?
answer
protostar, main-sequence, red giant, white dwarf
question
Compared to the star it evolved from, a white dwarf isq
answer
hotter and dimmer
question
Stars spend about ___ of their lives on the main sequence
answer
90%
question
Why do more massive stars have shorter main-sequence lives than smaller stars?
answer
Their greater mass means they have a greater core temperature, which in turns produces a greater fusion rate.
question
Rank the three types of clusters from youngest to oldest.
answer
stellar associations, open clusters, globular clusters
question
Cluster ages can be determined from
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the main sequence turnoff.
question
Which of the following statements about a globular cluster is true?
answer
Most stars in the cluster are yellow or reddish in color
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Which of the following statements about an open cluster is true?
answer
All stars in the cluster are approxiamtely the same age
question
Why is iron the endpoint of fusion in massive stars?
answer
The fusion of iron requires energy instead of producing it.
question
What types of stars end their lives with supernova
answer
Stars that are at least several times the mass of the sun.