Concept explainers
(a)
The reason so that the equation
(a)
Answer to Problem 33Q
Solution: The equation
Explanation of Solution
Given data:
The B-V color index is related to the color ratio
Formula used:
Magnitude difference related to the brightness ratio:
Here,
Explanation:
Recall the expression that relates the magnitude difference to the brightness ratio.
Now, as the above expression is for two different of star but the same expression can be applied if the same star is seen from different sides. So, to obtain the expression for the same, replace the subscript 1 and 2 by B and V, respectively. So, the B-V color ratio
Therefore, the provided equation is correct.
Conclusion:
The expression for the B-V color index is obtained by using the relation,
(b)
The B-V color indices for the Bellatrix, the Sun, and the Betelgeuse by using the data in table 17-1.
(b)
Answer to Problem 33Q
Solution:
Explanation of Solution
Given data:
Refer the table 17-1, to obtain the value.
The B-V color index is related to the color ratio
Formula used:
Magnitude difference related to the brightness ratio:
Here,
Explanation:
Refer the table 17-1:
The B-V color index is related to the color ratio
Refer the result of part (a):
The B-V color index is related to the color ratio
For Bellatrix:
Substitute
For Sun:
Substitute
For Betelgeuse:
Substitute
The B-V color index is positive for a cold star and negative for a hot star because the hot stars are assigned lower number on the apparent magnitude scale while the cold stars are assigned a higher number.
Conclusion:
The B-V color indices for the Bellatrix is
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Chapter 17 Solutions
Universe
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