Download astronomy practice test ch 9

astronomy practice test ch 9
Multiple Choice
Table 9-3
Use the following chart to answer the questions below:
Star
65 Tau
HR 4621
Pic
58 Ori
HR 2491
mv
4.2
2.6
1.5
Mv
0.3
1.8
6.0
d (pc)
Parallax
(sec of arc)
Spectral
Type
0.025
A7 IV
B2 IV
A7 V
M2 I
A1 V
20
0.005
2.5
____
1. Which star in Table 9-3 has the greatest diameter?
a. 65 Tau
b. HR 4621
c.
Pic
d. 58 Ori
e. HR 2491
____
2. A pair of stars orbit around one another in an elliptical orbit with a semimajor axis, "a", of 1 AU with an
orbital period, "P", of 1 year. What is the mass of the pair of stars?
a. m1 + m2 = a3 / P2 = 1 solar masses
b. m1 + m2 = a3 / P2 = 2 solar masses
c. m1 + m2 = a3 / P2 = 4 solar masses
d. m1 + m2 = a3 / P2 = 8 solar masses
e. m1 + m2 = a3 / P2 = 16 solar masses
____
3. Doppler shift observations of a spectroscopic binary star can enable astronomers to calculate ____ of its
individual stars.
a. the masses
b. the sizes
c. both a and b
d. neither a nor b
____
4. Binary (double) stars can be detected by
a. being seen as two separate stars with a telescope.
b. one star traveling a wiggly proper motion path across the sky.
c. one star dimming abruptly as another passes in front of it.
d. pairs of absorption lines seen in the spectrum of what appears to be one star.
e. all of the above
____
5. We know the white dwarf star Sirius B has a mass comparable to the Sun because of
a. its measured color
b. its measured temperature compared to Sirius A
c. it is part of binary star system with Sirius A.
____
6. The best true sample of the true members of different stars consists of
a. stars that appear brightest in the sky to an observer on the Earth.
b. all of the stars within our solar system.
c. all the stars within a given distance from Earth.
____
7. In the H-R diagram, 90 percent of all stars are
a. in the giant region.
b. in the supergiant region.
c. among the B stars.
d. among the G stars.
e. on the main sequence.
____
8. We can determine the surface temperature of a star from
a. studying its continuous spectrum.
b. studying its line absorption spectrum.
c. measuring the star's luminosity.
d. Both a and c
e. All of a, b, and c
____
9. Which stars always have large positive absolute magnitude?
a. Stars of high luminosity.
b. Stars of low luminosity.
c. Nearby stars.
d. Distant stars.
e. Not enough information given.
____ 10. If you compare two stars,
a. the one with the larger radius will always have the greater luminosity.
b. the one with the higher surface temperature will always have the greater luminosity.
c. the one with the smaller absolute magnitude will always have the greater luminosity.
d. the one with the larger surface area has the greater energy flux from its surface.
True/False
Indicate whether the statement is true or false.
____ 11. A star whose parallax is 0.01 seconds of arc is at a distance of 1,000 pc.
____ 12. The absolute magnitude of a star is the apparent magnitude it would have if it were 10 pc from Earth.
____ 13. Lines in the spectra of supergiant stars are broader than the same spectral lines in main sequence stars of the
same spectral type.
____ 14. Giant stars are members of luminosity class III.
____ 15. If a star is twice as hot as the sun and only half the sun's diameter, it will be less luminous than the sun.
____ 16. The method of spectroscopic parallax cannot be applied to stars beyond about 100 pc.
____ 17. The most common kinds of stars are low-luminosity stars.
____ 18. On the H-R diagram, lines of constant radius slants down from left to right.
____ 19. To observe a spectroscopic binary, we must be able to see both stars individually.
____ 20. An M star is hotter than an O star.
Completion
Complete each statement.
21. The parallax of the star 75 Leo is 0.10, and its apparent visual magnitude is +5.18. The absolute visual
magnitude of 75 Leo is ____________________.
22. ____________________ can be used to determine the distance to a star when the spectrum of the star can be
used to determine its spectral type and luminosity class.
23. Luminosity class IV objects are known as ____________________.
24. On the HR diagram below, indicate the location of the white dwarf stars.
25. Most stars on the H-R diagram are on the ____________________.
astronomy practice test ch 9
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
D
A
A
E
C
C
E
E
B
C
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
F
T
F
T
F
F
T
T
F
F
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
TRUE/FALSE
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
COMPLETION
21. ANS: +5.18
PTS: 1
22. ANS: Spectroscopic parallax
PTS: 1
23. ANS: subgiants
PTS: 1
24. ANS: An elongated region should be indicated that stretches from a luminosity of about 10 2 and spectral
type B to luminosity of about 10 4 and spectral type G. (See Figure 9-11 in the text.)
PTS: 1
25. ANS: main-sequence
PTS: 1