lab 5
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School
San Jacinto Community College *
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Course
1301
Subject
Astronomy
Date
Dec 6, 2023
Type
Pages
7
Uploaded by ProfessorTarsierMaster1091
HR Diagram
5-1
Lab 5
HR
D
IAGRAM
Part I:
Exploring the HR Diagram
1.
Check the appropriate region of the HR diagram corresponding to each description
below.
2.
Check the appropriate region of the HR diagram corresponding to each description
below.
3.
What is the general relationship between luminosity and temperature for stars that lie
along the main sequence?
Description
Top
Right
Bottom
Left
Hot stars are found at the:
x
x
Faint stars are found at the:
x
x
Luminous stars are found at the:
x
Cool stars are found at the:
x
Description
Upper
Left
Upper
Right
Lower
Right
Lower
Left
Large Blue stars are found at the:
x
Small Red stars are found at the:
x
Small Blue stars would be found at the:
x
Really Large Red stars are found at the:
x
HR Diagram
5-2
Part II:
Luminosity-Radius-Temperature Relation
4.
The equation below describes the luminosity of a star in terms of its radius and
temperature.
Use this equation to explain the results you found in the table of the
previous question.
The size and temperature effect the luminosity of the star exponentially and that the
temperature has a greater effect on the luminosity over the size
5.
Typing the values directly into the boxes in the Cursor Properties, determine the
radius of a star that has a surface temperature of 3000K and a luminosity equal to the
Sun (1 L
).
3.7
6.
Now determine the radius of a star that has the same surface temperature (3000K) but
a luminosity of 100 L
.
Based on the equation above, explain why this makes sense.
I think it should be 37 because the luminosity increases the their radius must increase
HR Diagram
5-3
7.
Now determine the radius of a star that has the same luminosity as the Sun (1 L
) but
a surface temperature of 30,000K.
Based on the equation above, explain why this
makes sense.
It should be .037 because the temperature is high so the luminosity is low, the radius
should be small
8.
Use the results from the previous questions to construct a “conceptual” HR Diagram.
You simply want to draw arrows showing the direction in which variables are
increasing.
a)
Draw in an arrow on the y-axis showing the direction of increasing “intrinsic
luminosity” of the stars. (This is complete for you.)
b)
Draw in an arrow on the x-axis showing the direction of increasing surface
temperature of the stars.
c)
Draw in an arrow showing the direction of increasing radius on the diagram.
(Hint:
this must be perpendicular to the isoradius lines.)
L
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HR Diagram
5-4
Figure 1: Conceptual HR Diagram
Part III:
Luminosity Classes
9.
Describe the general properties of stars in each of the categories.
DO NOT simply
list ranges of values for each, but describe the overall trend that causes a star to fall
into whatever category it belongs to.
Supergiants – extremely luminous, blue stars with radius less than 10
Giants – these stars are red and cold, the radius from about 3.5 to 400
Main Sequence (Dwarfs) – minimum radius is 1, the maximum radius is 12. The
luminosity and temperature can range from very low to very high
White Dwarfs – These stars are very dim when compared to other luminosity.
HR Diagram
5-5
Part IV:
A Random Sampling of Stars
10.
Describe the characteristics of the nearest stars.
You should cover their range of
temperatures, colors, luminosities, and sizes.
temperature ranges from about 2400 to the hottest plotted nearest star at 10,000. The rest
of them are from 2400 to 5200 degrees
11.
Use the tools of the HR Diagram to support the views of one of the three students.
Why are the stars we perceive as bright in the night sky really bright?”
(Hint:
You
may find the options labeled
both the nearest and brightest stars
and
the overlap
useful.)
the stars have luminosity and since they are closer in our solar galaxy, they appear
brighter
HR Diagram
5-6
12.
Do you think these stars are rare or very common among all of the stars of our
galaxy?
Explain your reasoning.
Are any assumptions involved in your reasoning?
Ii assume the are more common because there are a lot of them in a dense area
13.
Which of the two groups of stars (nearest or brightest) do you think is a better
representation of a random selection of stars? Explain your reasoning.
it's the brightest because those plotted points are more spread throughout the HR
diagram.
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HR Diagram
5-7
Lab Report:
In Hertzsprung Russell diagram, also called HR diagram, and astronomy, graph in
which the absolute magnitude of stars is plotted against their spectacle types. The sun is
around the middle of the sequence. In HR diagram the luminosity or energy output of a
star is plotted on the vertical axis.
I learned to figure out the luminosity of a star, and I learned how astronomers us the HR
diagram in their own studies when they study stars.