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Online Quiz



1

A star’s parallax can reveal its distance. Stars with larger parallaxes are _______ .
A)farther away
B)closer
C)the same distance as other stars
D)This is a trick question. Parallax cannot be measured for stars!
2

A star has a parallax of 0.04 arc seconds. What is its distance?
A)4 light years.
B)4 parsecs.
C)25 light years.
D)25 parsecs.
3

A star radiates most strongly at 400 nm. What is its surface temperature?
A)400 K.
B)4000 K
C)7500 K.
D)75,000 K
4

A 10th magnitude star is __ than a 5th magnitude star.
A)2 times brighter
B)2 times fainter
C)100 times brighter
D)100 times fainter
5

Stars have dark lines in their spectra because
A)the cooler atoms in their surface layers absorb the radiation at some wavelengths.
B)they simply don't emit light at certain wavelengths.
C)magnetic fields in the Earth's atmosphere absorb the radiation at some wavelengths.
D)The statement is false. Stars have bright emission lines in their spectra, but no absorption lines.
6

Which of the following stars is hottest?
A)an M star
B)an F star
C)a G star
D)an O star
7

What distinguishes the spectral class of a star?
A)Its brightness.
B)The lines in its spectrum.
C)Its distance.
D)Its velocity.
8

A binary star is a pair of stars that orbit around each other. By detecting this orbital motion, and using Kepler’s Laws and the Law of Gravitation, one can directly measure the stars'
A)temperatures.
B)luminosities.
C)masses.
D)distances.
9

What is a spectroscopic binary?
A)A spectroscopic binary looks, to us on Earth, like a single star, but its spectrum shows double lines that shift.
B)A visual binary for which we have spectra of both stars.
C)A visual binary in which one or both stars have peculiar spectra.
D)A visual binary which is shown by its spectrum to be a single star.
10

The H-R diagram is a plot of stars'
A)temperature vs. mass.
B)mass vs. luminosity.
C)luminosity vs. temperature.
D)mass vs. diameter.
11

What is the main sequence?
A)A region of cool, luminous stars in the upper right corner of the H-R diagram.
B)A region of hot, dim stars in the lower left corner of the H-R diagram.
C)An approximately straight line on the H-R diagram along which 90% of stars lies.
D)The order in which spectral types are listed.
12

A cool but very luminous star must have
A)a very large radius.
B)a very small radius.
C)a very small mass.
D)a very low velocity.
13

Cooler, less luminous main sequence stars have
A)higher masses.
B)lower masses.
C)the same masses as hotter stars.
D)masses that vary widely
14

The period of a variable star is the time it takes its light to vary from
A)minimum to maximum light.
B)maximum to minimum light.
C)maximum light to the subsequent maximum.
D)when it leaves the Main Sequence to when it becomes a white dwarf.
15

Where are Red Giants on the HR diagram?
A)Upper left
B)Upper right.
C)Lower left
D)Lower right







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