GS107Homework5_7AUG22(4)
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Rogue Community College *
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Course
107
Subject
Astronomy
Date
Dec 6, 2023
Type
docx
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5
Uploaded by SuperHumanOxideBison32
Name:
Derek Greene
GS 107 Homework #5
Summer 2022
(10 points each for 50 total points)
1.
Multiple Choice
A. ____
Our Sun is less massive than most stars.
a.
True
b. False
B. ___
Which is a method of detecting exoplanets?
a.
Doppler shift
c. Transit in front of the star
b.
Direct detection
d.
All are methods of detecting exoplanets
C.
___ Kepler’s 3
rd
Law can be used to determine mass information in
binary star systems.
a. True
b. False
D. ___ The HR diagram cannot be used to determine the mass of a star.
a. True
b. False
E.
___ Stars are formed primarily due to gravity.
a. True
b. False
c.
1
2.
Consider the HR Diagram shown below.
All of your answers will
necessarily be approximate.
A. If a star has a luminosity 10,000 times that of the Sun at a temperature of
30,000 K, what would its radius be?
Approximately 9 solar masses
B.
For the above star, what would its mass be?
Approximately 10 solar masses
C.
Consider a particular star at 7000 K.
What color would it be?
(Hint:
blackbody radiation is helpful here.)
Yellow
D. For the above star, report a luminosity and radius that would fit the
criteria.
10^-4 solar Lumosities
2
3.
There are stars much more massive than the Sun.
An example would be
BAT99-98
https://en.wikipedia.org/wiki/List_of_most_massive_stars
which
is 226 solar masses.
There are also those which are much less massive.
One
such star is EBLM J0555-57b which has a mass as small as 0.0777 solar
masses
https://en.wikipedia.org/wiki/List_of_smallest_stars
.
What are the
luminosities of these stars (relative to the Sun) based on the mass-luminosity
relation?
3
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4.
Consider a binary star system with each star essentially the same mass.
If
there is a distance of 3 AU between the two stars with a period of 4 years,
what is the mass of EACH star?
4
5.
Explain how a star is born.
Include information about where the material
comes from as well as why it gathers together.
Address what is required to
make it a star rather than just a gas planet.
Diagrams will be helpful.
Stars are born primarily due to gravity. The material used in forming stars is
floating around in space and is largely hydrogen due to its simple atomic structure.
As these atoms of hydrogen cluster together due to gravity they compress to a
point where the temperature is high enough for fusion to occur. This in turn causes
the start to start emitting massive amount of energy via the proton-proton chain. If
the hydrogen is not compressed to the point of fusion, it may become a gas giant
instead.
5