HR diagram-lab online-1
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School
University of Nebraska, Omaha *
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Course
1350
Subject
Astronomy
Date
Apr 29, 2024
Type
docx
Pages
10
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NAME______________________
CLASS_________
Instructions:
Go to web site http://astro.unl.edu
. Click on the Nebraska astronomy ap-
plet project and then go to NAAP Modules(at top of screen) and pick HR Diagram. Read the materials and complete the guide below and complete the exer-
cises and complete the document below—the background materials will help you answer the questions—the flash demonstration will help you com-
plete the rest.
ON LINE LAB 10
Nebraska Astronomy Applet Project
Student Guide to the
HR DIAGRAM
_____________________________
NAAP – HR Diagram Explorer 1/10
HR Diagram – Student Guide
Pretest Score: 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.
Star
Surface Tempera-
ture K
Spectral Type
Color
Betelguese
3,530
M2
Orange
Arcturus
4,300
K5
Yellow
The sun
5,830
G2
Yellow
Procyon A
6,530
F5
Yellow-White
Sirius A
9,145
A1
White
Rigel A
11,000
B9
White-Blue
Delta Orionis
33,200
O9
Blue
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. NAAP – HR Diagram Explorer 2/10
2.Complete the following table related to stellar luminosities in solar units using the equation
. Radius (R
⊙
)
Temperature (T
⊙
)
Luminosity (L
⊙
)
1
1
1
1
2
16.8
3.02
1
9
1
1/2
0.057
3.The mass luminosity relation describes the mathematical relationship between lumi-
nosity and mass for main sequence stars. It describes how a star with a luminosity of 2 M
⊙
would have a luminosity of 11.31 L
⊙
while a star with luminosity of 3,160 L
⊙ would have an
approximate mass of 10 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 indi-
cated by a red x. This active location can be dragged around the diagram. The options
panel
allows you control the variables plotted on the x-axis: (temperature, B-V, or spec-
tral 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
NAAP – HR Diagram Explorer 3/10
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 ac-
tive location on the HR Diagram. Note that the size of the sun remains constant. NAAP – HR Diagram Explorer 4/10
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