Unformatted text preview: 27) The Sun rotates: A) Very quickly on its axis, taking less than one day to go around once. @ Differentially, with the equator taking about 25 days to go around once, and the polar
regions taking much longer.
C) Differentially, with the equator taking about 25 days to go around once, and the polar areas
taking less time.
D) Very slowly on its axis, taking a year to go around once (thus we only see one side of the
Sun from Earth). .
E) The Sun does not rotate. 28) The critical temperature to initiate the proton-proton cycle in the cores of stars is:
A) 3,000 K
B) 5,300 K
6 10 million K E) 100 million K 29) What is it about the Sun's corona that astronomers don't understand?
A) No one knows why that part of the Sun's atmosphere does not drift away into space.
E) During total solar eclipses, the corona sometimes disappears ﬁorn view.
The corona seems to absorb 2/3 of the neutrinos that pass thorough it.
@The corona is much hotter than layers of the Sun that are closer to the solar interior.
E) The Sun's corona extends to the outer reaches of the solar system. 30) In light ofmodern solar system theory, why do the orbits of the planets all lay in the same
A) The Sun's gravity forced them into these orbits.
B The angular momentum of the solar system was kept to a minimum this way.
©The early solar nebula ﬂattened into a disk.
) Comets would have wiped out any not in this protected plane.
E) This happened purely by chance. Problems 1) A blackbody is brightest at a wavelength of 1200 nm. (a) At what wavelength would the
peak of the blackbody spectrum appear if its temperature was tripled? (b) Determine the ﬂux
of such a blackbody (You can leave your answer in units of Stefan-Boltzmann constant, 0). CD Ame-cc: ____o.20\ cm ; ‘IE ”(—3 3T , Rm” —3 ﬁrms/3
0 (lg CM
_ -‘t z 93:“; *- :4250 K
b) F‘- O— l / T gmaﬂ'nep‘) 400K iO_ cm
‘i '5 [,3
F: O'CZFZDBO) ~ 2 END 6—: ...
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- Spring '09