what is the end state of the former star's core? - ANSWERS-a white dwarf; held up
against gravity not by gas pressure anymore, but by pressure of electrons; about
the size of earth
brown dwarfs (failed stars) - ANSWERS-have mass less than 8% of the Sun and
never heat enough to have nuclear reactions in their core
lifespan of more massive stars - ANSWERS-much shorter as mass increases
hydrogen burning in the main sequence, what is burned when hydrogen is
exhausted? - ANSWERS-helium burning in the core (swelling into red giant)
after helium burning is exhausted, what is burned? - ANSWERS-carbon burning
and then even heavier nuclei burning (turning to red giant)
"onion skin" model - ANSWERS-concentric shells of fusion zones involving
different chemical elements, with the heaviest gong on towards the core (after
nuclei burning)
when does burning in the main sequence stop? - ANSWERS-stops around iron (Fe)
because iron is very stable and reactions involving iron don't produce much
energy - instead cost more energy than they release
,A high-luminosity star...
A. is always at a larger distance than a low-luminosity star
B. emits more light than a low-luminosity star
C. is always redder than a star with a lower luminosity
D. is at a lower temperature than a low-luminosity star
E. is always at a smaller distance than a low-luminosity star - ANSWERS-B
If a red giant appears the same brightness as a red main sequence star, which one
is further away?
A. the red giant
B. we cannot tell
C. it depends on the phase of the moon
D. the main sequence star
E. they are at the same distance - ANSWERS-A
The heaviest nuclei of all are formed...
A. during helium burning
, B. as part of the p-p chain
C. during the carbon burning
D. during supernova explosion
E. during all stages of stellar evolution of massive stars - ANSWERS-D
Fill in the blank in the following chemical reaction that occurs in the Sun:
Hydrogen-2 + proton = + energy:
A. hydrogen-2
B. Hydrogen-1
C. Helium-3
D. Carbon-12
E. Helium - 4 - ANSWERS-C
Which of the following has the smallest radius?
A. type A main sequence star
B. main sequence star with surface temperature 8000K
C. type K main sequence star
D. white dwarf
E. neutron star - ANSWERS-E
Why does the main sequence part of a star's life end?
A. the helium in the core is exhausted
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