NAME
____________________________________________________________________________
Multiple Choice Questions -- 20 questions @ 1 points per question
----> 20 points.
Select the best answer for each question.
1. Around _______ of observed stars are Main Sequence stars.
a. 10 %
b. 50 %
c. 85-90 %
d. 70 %
e. 25 %
2. Astronomers know that iron atoms are present in the Sun because _____ .
a. by analogy with the Earth, we know that iron atoms must be present in
the Sun
b. we identify iron abosrption lines in the spectrum of the Sun
c. the Sun appears reddish as sunset indicating that it contains large amounts
of rust
d. the Sun produces energy through nuclear fusion reactions in its core
e. we see the closely related element silicon in the spectrum of the Sun
3. Hydrogen absorption lines are most prominent in ____ .
a. A type stars
b. B type stars
c. C type stars
d. G type stars
e. M type stars
4. The large change in the appearance of stellar spectra as
you move through the spectral sequence is caused by _____ .
a. small planets orbiting about the stars
b. a change
in the surface temperatures of the stars
c. a change in the chemical
composition of the stars
d. a change in the luminosity of the stars
e. the varying ages of the stars
5. The Russell-Vogt Theorem states that the properties of a star are
determined primarily by the star's _____ .
a. luminosity and radius
b. mass and luminosity
c. mass, chemical
composition, and radius
d. radius and chemical composition
e. mass and
chemical composition
6. Most stars show ________ spectra.
a. only bright continuous spectra
b. strong continuous spectra with many superimposed bright emission lines
c. primarily bright emission line spectra
d. show absorption line spectra
e. spectra that tend to evolve from high-to-low temperatures as they age, that
is, as they change from M to O stars over the course of their lives
7. By the word spectrum, we mean _______ .
a. the spreading of light into its component colors
b. the relation between the frequency and wavelength of electromagnetic radiation
c. the relation between the frequency and energy of electromagnetic radiation
d. a and b only
e. a, b, and c
8. The most massve stars on the Main Sequence _____ .
a. are the M type stars
b. are the hottest ones
c. are the least luminous ones
d. depends strongly on the age of the star
e. are the G type stars
9. The regions in the Hertzsprung-Russell diagram where there are
concentrations of stars are _____ .
a. regions in the Galaxy where stars tend to congregate
b. are long-lived stable phases in the evolution of stars
c. where stars have used up their nuclear fuels and are collapsing
d. known as globular clusters
10. The most numerous stars in our galaxy are ________ .
a. normal giants with large mass
b. super-giants with large mass
c. normal giants with small mass
d. Main Sequence stars with high mass
e. Main Sequence stars with low luminosity
11. The determination of annual trigonometric parallax
is important because it allows
the direct determination of _____ .
a. the masses of stars
b. the surface temperatures of stars
c. the orbital periods of binary stars
d. the distances to stars
e. the chemical composition of stars
12. Strong lines produced by molecules such as titanium oxide, are
found in _____ stars.
13. An absorption line is produced when _____ .
a. an electron jumps to a higher energy level in an atom
b. a neutron jumps to a higher energy level in an atom
c. an electron falls from a high energy level to a lower energy
level in an atom
d. an electron absorbs enough energy to escape from an atom
a. a neutron jumps to a higher energy level in an atom
14. The mass-luminosity relationship for main sequence stars _____ .
a. helps to show that the most massive main sequence stars have
lifetimes of less than 1 million years
b. is very well-determined because it is
based on measurements of the masses of nearly 100 billion stars
c. shows that the most massive main sequence stars are those with spectral
class M
d. was first found by Hertzprung and Russell in the early 1900s
15. Atoms are composed of neutrons, protons, and electrons. The type of
element is determined by _____ in the atom.
a. the number of protons plus neutrons contained
b. the number of protons plus electrons contained
c. the number of neutrons contained
d. the number of protons contained
e. the total number of protons plus neutrons plus eletrons contained
16. The spectral type of the Sun is _____ .
a. O6
b. A2
c. F8
d. G2
e. S2
17. A K5 V star is _____ a K5 I star.
a. hotter than O6
b. larger than
c. cooler than
d. smaller than
e. the
same brightness as
18. The most important property used to identify a star is _____ .
a. its radius
b. its luminosity
c. its mass
d. its
surface temperature
e. its distance
19. Atoms produce ______ .
a. sets of emission and absorption lines with energies unique to each
element
b. sets of emission lines with slighlty higher energies than the sets of
absorption lines which they produce
c. emission lines which appear only in the ultraviolet portion of the
electromagnetic spectrum
d. continuous spectra similar to blackbody spectra if they are placed in a
container at low density
e. absoprtion lines at slightly higher energies in hot stars than the
absorption lines which they produce in cooler stars
20. Bootstrapping refers to ______ .
a. a method used to determine the masses of stars
b. a method used to determine the temperatres of stars
c. a method used to determine the distances to celestial objects
d. a method used to determine ages of stars and celestial objects
e. a method used to determine the radii of stars
Short Answer Questions -- 3 questions worth
a total of 30 points
1. The strengths of hydrogen lines change along the spectral sequence.
[8 points]
2. Spectral Formation [8 points]
a. State Kirchhoff's Three Laws of Spectral Formation.
b. Describe how Kirchhoff's Laws explain how the spectrum of the Sun
changes as the Sun undergoes an eclipse
3. Hertzprung-Russell Diagram [14 points]
a. Sketch a Hertzsprung-Russell (H-R)
diagram. Be sure to label the axes and indicate the locations of the
Super-giants, normal giants, Main Sequence stars, and white dwarfs.
Indicate the luminosity classes for the
Super-giants, normal giants, Main Sequence stars, and white dwarfs.
b. Circle the region in the Hertzprung-Russell diagram where the bulk of the
observable stars are found.
c. Indicate the region in the Hertzprung-Russell diagram where the smallest
stars are found. Use an arrow the direction of increasing radius for stars
given temperature but increasing luminosity.
Part | Points |
Multiple Choice | |
Short Answer | |
Total | |