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ASTRONOMY CHAPTER 12
from book and outline paper
30
Astronomy
Undergraduate 1
04/01/2009

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Cards

Term
What four laws determine the structure and evolution of a star?
Definition
1. hydrostatic equilibrium
2. energy transport
3. conservation of mass
4. conservation of energy
Term
What is the maximum mass of a main sequence star?
Definition
100 solar masses
Term
Where do stars of a very high mass loss mass?
Definition
in strong stellar winds
Term
What is the minimum mass of main sequence stars?
Definition
.08
Term
Objects of mass less than .08 are called what?
Definition
brown dwarfs
Term
Why do stars have finite lifetime?
Definition
because they have a final supply of H
Term
Do massive stars have shorter or longer lifetime?
Definition
shorter
Term
What is the core filled with after Hydrogen is done burning?
Definition
helium
Term
what exists around the core?
Definition
a shell of burning hydrogen
Term
When the star expands to become a red giant, what happens to the surface?
Definition
it cools
Term
True or false: at some point the sun will expand past the earths surface
Definition
true
Term
What is the new state called with Hydrogen in the core stops burning and the matter enters this new state?
Definition
degenerate matter
Term
What happens in Triple Alpha Process?
Definition
helium is converted into carbon, oxygen and energy. (a core of C and O are formed)
Term
Stars more massive than _________ masses can fuse elements heavier than carbon and oxygen.
Definition
8 solar masses
Term
Stars of mass less than 4 times the mass of the sun stop fusion at the formation of what?
Definition
Carbon oxygen core
Term
Stars of mass greater than 8 times the mass of the sun stop fusion at the formation of what?
Definition
Fe core
Term
Which stars never burn anything heavier than hydrogen?
Definition
red dwarfs
Term
What can be used as evidence of stellar evolution? why?
Definition
star clusters, because all the stars will have the same age
Term
More massive stars evolve more or less quickly than less massive stars?
Definition
more quickly
Term
If the stars are plotted on a H-R diagram, what stars would be missing?
Definition
the more massive stars
Term
What do mathematical stellar models show?
Definition
how rapidly a star uses its fuel in each layer
Term
What is the zero-age main sequence?
Definition
the line in the H-R diagram where contracting stars begin fusing hydrogen and reach stability
Term
What does the life expectancy of a main sequence star depend on?
Definition
its mass
Term
What does helium fusion produce?
Definition
carbon and oxygen
Term
What are the two types of star clusters?
Definition
1. open clusters
2. globular clusters
Term
What is an open cluster?
Definition
contains 100 to 1000 stars and have open, transparent appearnce; young
Term
What are globular clusters?
Definition
10^5 to 10^6 stars and are densely packed in a spherical shape; older
Term
What is the turn off point?
Definition
the location on the main sequence where the stars turn off to the right and become giants
Term
What is the difference between variable stars and intrinsic variable stars?
Definition
variable stars: change in brightness
I.V.S: change in brightness because of internal processes
Term
What are two examples are proof that stars evolve?
Definition
the cepheid and RR Lyrae variable stars
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