PHYS 1403 Lab 7: APPARENT & ABSOLUTE VISUAL MAGNITUDE
Worksheet
Enter your answers to each question in the data tables and yellow highlighted areas
below. When completed, please save and upload this file to the assign
...
PHYS 1403 Lab 7: APPARENT & ABSOLUTE VISUAL MAGNITUDE
Worksheet
Enter your answers to each question in the data tables and yellow highlighted areas
below. When completed, please save and upload this file to the assignment – Lab 7 – in
Canvas.
PRELAB QUESTIONS
1. The apparent visual magnitude of Canopus is –0.6 and that of Hadar is +0.6. Which
star is brighter? How do you know?
Canopus is the bigger star because its apparent visual magnitude is smaller than
Hadar’s.
2. What is the absolute visual magnitude of a star?
The absolute visual magnitude of a star is how bright a star appears at a distance of 10
parsecs or 32.6 light years.
3. Epsilon Eridani has an apparent visual magnitude of + 3.7. Will it will be visible with
the naked eye? How do you know?
Yes it will be visible to the naked eye because it is able to detect a visual magnitude of
6.0
4. Ross 128 has an apparent visual magnitude of +11.1. Will it will be visible with the
naked eye? How do you know?
No, it will not be visible to the naked eye because it is only able to detect a visual
magnitude of 6.0
5. Ross 128 is 3.4 parsecs from us. If it were moved to 10 parsecs, would it appear
brighter or dimmer? Why?
The star would appear dimmer due to the fact that the bigger the number, the farther
away that specific star is and it will appear more dim to us.
EXERCISE
In this lab, we will use Stellarium find information about individual stars. First, you will
need to start the program. After the program has started, move your cursor to the left
side of your screen to bring up the vertical menu, and click the “Sky and viewing options
1window” icon. Click the “Sky” tab, and un-check the box that says “Show atmosphere”.
Daylight should fade and stars should now be visible (although the sun may still be
displayed in the sky). You can move around by simply clicking on the screen and
moving the mouse. We also need to remove the ground from the screen. To do this,
open the Sky and viewing options window again, and click on the “Landscape” tab.
Now, un-check the boxes labeled “Show ground” and “Show fog”. This should remove
the ground from the screen. Close the Sky and viewing options window, and now you
are ready to start the exercise
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