University of Michigan - Department of Astronomy

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Version: Magnitude

updated: 04/19/2000


Spectral Classification and the Pleiades - Worksheets

Data

Table 1: The Pleiades Spectral and Magnitude Data

Star Number Spectral Type Spectral Lines Used To Classify Photo Diameter App. Blue Magnitude (mB)
1        
2        
3        
4        
5        
6        
7        
8        
9        
10        

 

Graph 1: Pleiades H-R Diagram

Graph 1: H-R Diagram

 

 

Distance modulus m - M =
Distance pc ly

Concluding Questions

  1. If you plot apparent magnitude vs. spectral type for a random group of stars in the sky, why don't you trace out main sequence? Why do you see a main sequence when you plot the data for the stars in the Pleiades?









  2. If you knew, with no experimental errors, the apparent magnitudes and spectral types of all the stars in the Pleiades, describe how your H-R diagram would change. Also, carefully sketch what you think this would look like.














  3. You plotted other stars on your H-R diagram besides the Pleiades members. What quantities or characteristics of these stars did you plot? What do we need to know about these stars to obtain these values from observed quantities? (and what quantities do we observe?)









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