Assignment- Stellar Classification
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Solano Community College *
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Course
010
Subject
Astronomy
Date
Apr 3, 2024
Type
Pages
9
Uploaded by DeanDanger13814
Name: NAAP – HR Diagram Explorer 1/9 HR Diagram – Student Guide Background Information Work through the background sections on Spectral Classification, Luminosity, and the Hertzsprung-Russell Diagram. Then complete the following questions related to the background information. Question 1:
The table below summarizes the relationship between spectral type, temperature, and color for stars. Note that the surface temperature of the stars in the table increases. Question 2:
Complete the following table related to stellar luminosities in solar units using the equation 2
4
L
R T
. Star Surface Temperature K Spectral Type Color Betelguese
M2
Arcturus
4,300
G2 Yellow
Procyon A F5 Yellow-White Sirius A A1 White Rigel A 11,000 Delta Orionis O9 Radius (R
⊙
) Temperature (T
⊙
) Luminosity (L
⊙
) 1
1
1
2
1
9
1
1/2
NAAP – HR Diagram Explorer 2/9 Question 3:
The mass luminosity relation 3.5
L
M
describes the mathematical relationship between luminosity and mass for main sequence stars. It describes how a star with a mass of 2 M
⊙
would have a luminosity of _____________ L
⊙
while a star with luminosity of 3,160 L
⊙
would have an approximate mass of ________________ M
⊙.
HR Diagram Explorer Open the HR Diagram Explorer
. Begin by familiarizing yourself with the capabilities of the Hertzsprung-Russell Diagram Explorer through experimentation.
An actual HR Diagram
is provided in the upper right panel with an active location
indicated by a red x. This active location can be dragged around the diagram. The
options panel
allows you to control the variables plotted on the x-axis: (temperature, B-
V, or spectral type) and those plotted on the y-axis (luminosity or absolute magnitude).
One can also show the main sequence, luminosity classes, isoradius lines, or the
instability strip. The Plotted Stars
panel allows you to add various groups of stars to the
diagram.
The Cursor Properties
panel has sliders for the temperature and luminosity of the active
location on the HR Diagram. These can control the values of the active location or move
in response to the active location begin dragged. The temperature and luminosity (in solar
units) are used to solve for the radius of a star at the active location.
The Size Comparison
panel in the upper left illustrates the star corresponding to the
active location on the HR Diagram. Note that the size of the sun remains constant.
NAAP – HR Diagram Explorer 3/9 Exercises
Drag the active location around on the HR Diagram. Note the resulting changes in the
temperature and luminosity sliders. Now manipulate the temperature and luminosity
sliders and note the corresponding change in the active location.
Question 4:
Check the appropriate region of the HR diagram corresponding to each description below.
Drag the active location around on the HR Diagram once again. This time focus on the
Size Comparison panel.
Question 5:
Check the appropriate region of the HR diagram corresponding to each description below.
Check show isoradius lines. Note that at each point on a green line, stars have the same
value of radius. Use these isoradius lines to check your answers in the table above.
Description
Top Right Bottom Left
Hot stars are found at the: Faint stars are found at the: Luminous stars are found at the: Cool stars are found at the:
Description Upper Left Upper
Right Lower Right Lower
Left Large Blue stars are found at the: Small Red stars are found at the: Small Blue stars would be found at the: Really Large Red stars are found at the:
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NAAP – HR Diagram Explorer 4/9 Question 6:
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.
In addition to the isoradius lines, check show luminosity classes
. This green region
(dwarfs V) is known as the main sequence and contains all stars that are fusing hydrogen
into helium as their primary energy source. Over 90% of all stars fall in this region on
the HR diagram. Move the active cursor up and down the main sequence and explore the
different values of stellar radius.
Question 7:
Describe the sizes of stars along the main sequence. What are stars like near the top of the main sequence, the middle, and the bottom?
The background pages of this module talked about the mass-luminosity relationship for
stars on the main sequence:
Question 8:
What can you conclude about the masses of stars along the main sequence? 2
4
4
L
R
T
3.5
L
M
NAAP – HR Diagram Explorer 5/9
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NAAP – HR Diagram Explorer 7/9
NAAP – HR Diagram Explorer 8/9
NAAP – HR Diagram Explorer 9/9
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