Download Practice Homework 2: Properties of Stars 1. Star A is 100 times more

Practice Homework 2: Properties of Stars
1. Star A is 100 times more luminous than star B. Star A is 100 times nearer to us than star
B. how Do the apparent brightness of the two stars compare
2. The temperature of gas filled in box A is more than the temperature of gas filled in box B.
whose molecules have more average kinetic energy? Which gas has more total heat energy?
3. A star is found to emit maximum power at the wavelength 0.34µm (micro meter). What is
the temperature of the star?
4. Put the following stars into a sequence of mperature from cold to hotter. F 3, F 8, O2, G6,
M 2, K9, B1, G3, M 3
5. An Astronomer claims that he has found sodium in a certain star. Explain how he might
have discovered it?
6. The Light in sun is created in the interior of the sun which is extremely hot and dense while
the outer layers are relatively colder. What kind of spectrum it should produce? Helium in
the sun causes absorption at certain frequencies, in which regions of sun do you think this
mostly occurs?
7. The energy difference between the first and second energy level in hydrogen is greater than
that of helium? An electron drops from the second level to the first in both of the atoms.
Whose wavelength would be longer? From helium or from hydrogen? Whose frequency
would be higher?
8. The three main lines belonging to the spectrum of hydrogen in the visible region are 410 nm
, 434 nm, 656 nm suppose you observe the spectrum of a star. Apart from some junk you
see the following absorption lines 414 nm, 438 nm, 660 nm What do you conclude about the
star?
9. What kind of star are the followings: O2 V,G1 I,M3 III, B5wd
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