Notes 3 Exam Flashcards
What is luminosity?
total light energy radiated by a star each second-watts
Does the luminosity of a star depend on the star’s distance from us?
no
Apparent brightness = how bright an object appears; the farther away a star is the smaller its apparent brightness.
From which layer of the sun does the sun’s light come?
core
Name the interior parts of the sun.
core, radiation zone, convection zone
Name the atmospheric parts of the sun.
Chromosphere, Transition zone, Corona
What is the temperature of the sun’s surface?
1,000,000 K
What does the chromosphere tell us about the sun?
reveals the elemental composition of the Sun
What’s unique about the coronal layer of the sun?
it is brightest in the x-ray portion of the electromagnetic spectrum. sun spots, prominences, solar flares
What is the most significant feature about the core of the sun?
source of the sun’s energy
What single property of a star determines its final state at “death”?
shell burning
What will happen to the sun when it runs out of hydrogen which is hot enough to fuse?
The Sun’s core will contract (shrink) and it will start to fuse helium in the core and hydrogen fusion will start up in a shell round the core. This will heat up the Sun and it its outer layers will therefore expand and it will turn into a red giant.
Which two properties allow you to place a star on the Hertzsprung-Russell diagram?
Luminosity and surface temperature (or spectral class)
What is a red giant star?
A red giant star is a star with a mass like our Sun that is in the last phase of its life
Will the sun ever be a nova? Why or why not?
No, because it is not in a binary system.
Will the sun ever be a supernova? Why or why not?
No, because it is not large enough
What determines the changes in a star’s life cycle?
the initial mass
What is the astronomical origin of the iron in your blood?
a high mass star and supernova
Why do supernovas occur?
While the core of a high mass star burns heavier and heavier nuclei, layers of lighter nuclei from the previous stage of burning, are burning in successive shells around that core. When iron is all that’s left in the core, fusion ends and a supernova occurs.
What temperature is required for hydrogen fusion? For helium fusion?
10-14 million degrees Kelvin
100 million degrees Kelvin
What do all main sequence stars have in common?
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A main-sequence star doesn’t collapse because of the outward _____ produced by hot gases in the stellar interior.
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While a star is on the main sequence, _____ is slowly consumed in the core and _____ builds up.
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At the end of its main-sequence lifetime, a star’s core starts to _____.
shell burn
What type(s) of objects remain after a high mass star dies?
neutron star or black hole
What type(s) of objects remain after a low mass star dies?
white dwarf will fade and dim like a chunk of charcoal on a grill that is off.
When the sun evolves past the main sequence stage of life will its luminosity and surface temperature change? If so, how so?
Yes, it gets brighter and hotter then it dims and gets cooler. Then gets hot and bright again then it cools.
