STUDY GUIDE FOR PART 4
The Sun and Stars
INTRODUCTION:
We continue our journey
through the universe in this part by looking at those lights in the sky, the
stars. What are they made of? How do they work? How far away are they? Are there
different kinds of stars? We ask all of these questions.
In Section A we look at our
own star, the sun. It is the closest, and so the most important star to us, and
at the same time the easiest star to observe. By knowing something about the
sun, we will have a standard by which we can compare other stars.
In Section B we consider
the properties of stars in general. By considering these properties we can
begin to determine how far away the stars are and how our sun fits into the
general scheme.
In Section C we study
multiple star systems to see what additional information we can obtain when two
(or more) stars orbit each other.
In Section D we consider
the things other than stars that are out there: interstellar atoms, dust, and
nebulae. These are related to the birth and death of stars considered above and
will be important when we consider galaxies and the universe in Part 5.
In Section E we try to
first of all categorize all the different types of stars. We then try to relate
these categories into an evolutionary scheme for stars that is based on how we
think a star works.
A. The Sun and its Radiation
[text:
Ch. 9, all]
OUTLINE:
Study Questions for Part A:
1. What is a sunspot?
*2. What is the sunspot cycle? How long is
it?
3. Describe a solar flare.
4. What is the solar wind?
*5. Be able to discuss possibilities and
limitations of solar energy.
B. Basic Properties of Stars
[text:
Foundations III, all; Ch. 10, Sections 1-5]
OUTLINE:
Study Questions for Part B:
*1. What is parallax?
2. Distinguish between proper motions and
parallax.
*3. Distinguish between brightness and
luminosity.
*4. Distinguish between apparent and
absolute magnitudes.
5. Know the spectral classifications and how
they relate to the color and temperature of the stars.
**6. Draw the H-R diagram and indicate the
position of the main sequence, the sun and the two stars in question #7 below.
**7. Choose two stars excluding the sun and
know (1) their distances from earth; (2) their absolute and apparent magnitude;
(3) their stellar classifications; and (4) in what constellation each is.
C. Binary and Multiple Star Systems
[text:
Ch. 10, Sections 6-9]
OUTLINE:
Study Questions for Part C:
1. What are the three ways of detecting a
binary star system?
2. Be able to interpret a light-curve from a
binary star system.
3. Know what the mass-luminosity relation
is.
4. What is the percentage of single versus
multiple star systems?
D. Interstellar Atoms, Dust, and Nebulae
OUTLINE:
Study Questions for Part D:
1. Name two effects of stellar matter on
light.
2. How are nebulae related to star
formation?
3. How are nebulae related to star death?
E. Stellar Evolution
[text:
Ch. 11, all; Ch. 12, all; Ch. 13, all]
OUTLINE:
Study Questions for Part E:
*1. Distinguish between fission and fusion. Which
process does the sun employ? Which process do today's nuclear power reactors
employ?
*2. What does the sun "burn" as
fuel?
*3. How is a star born, and where does it
get its energy to light the nuclear fires?
*4. How long will the sun be on the main
sequence (total time)? How long has it been on the main sequence? How long
before it moves off the main sequence?
5. What determines a star's position on the
main sequence?
*6. What is the source of energy after a
star has exhausted its hydrogen supply in its core?
*7. What is a Cepheid variable? Locate it on
the H-R diagram.
*8. What is the period-luminosity
relationship for a Cepheid variable, and how is it useful?
9. Be able to locate giants, supergiants,
and white dwarfs on the H-R diagram.
10. What is a nova?
*11. What is a supernova?
12. What is a dwarf star?
13. What is a neutron star?
14. What is a pulsar?
*15. What is a black hole?
*16. What determines whether a star will die
as a dwarf, neutron star, or black hole?
*17. Be able to show the life cycle of a
star like the sun on the H-R diagram.
Study TRUE/FALSE Questions for all of
Part 4:
(questions
similar to these may appear on the test)
_____ a) The diameter of the sun is
approximately 0.1% of the earth-sun distance. [Here "about" means
within a factor of 5 either way.]
_____ b) The nearest star is about 250,000
A.U. from the earth. [Here "about" means within a factor of 5 either
way.]
_____ c) Absolute Magnitude is a measure of
a star's brightness.
_____ d) Planetary nebulae are clouds of
dust and gas out of which the planets form.
_____ e) The sun will probably go supernova
sometime, probably in about 5.5 billion years.
_____ f) Vega is a star that has a stellar
classification of A0 V. From this we can infer that Vega is more massive than
the sun.
_____ g) The heaviest elements (gold, lead,
uranium, etc.) are thought to be made in supernova explosions and not in the
interior of stars like carbon and oxygen are.
_____ h) The sun will eventually (in about
5.5 billion years) turn into a red giant whose radius will reach out to about
the earth's orbit.
_____ i) Closed or globular clusters of
stars are groups of tens to hundreds of young often massive stars often found
in dust clouds.
_____ j) A K9 Ia star has approximately the
same surface temperature as a K9 V star.
_____ k) More massive stars last longer on
the main sequence than less massive stars because they have more fuel (mass).