Concept explainers
- Which star is brightest?
- Which star is most luminous in absolute magnitude?
- Which star is largest?
- Which star is farthest away?
Answer to Problem 10P
- The brightest star is a.
- The most luminous star in absolute magnitude is c.
- The largest star is c.
- The farthest away star is d.
Explanation of Solution
Given:
Table
Star | Spectral type | |
a | G2 V | 5 |
b | B1 V | 8 |
c | G2 Ib | 10 |
d | M5 III | 19 |
e | White dwarf | 15 |
Formula used:
Absolute magnitude of the star is given as
Calculation:
Consider the H-R diagram
Figure.1
(a)
The classification of the star is G2 V, here G suggests that class of the star, and V suggest that it is a main sequence star. By the help of this we can estimate the absolute magnitude of the star using H-R diagram
It is clear from the figure that the absolute magnitude of the star is 5
Apparent magnitude of the star is give as
Plugging the values in the above equation
(b)
The classification of the star is B1 V, here B suggests that class of the star, and V suggest that it is a main sequence star. By the help of this we can estimate the absolute magnitude of the star using H-R diagram
It is clear from the figure that the absolute magnitude of the star is -1
Apparent magnitude of the star is give as
Plugging the values in the above equation
(c)
The classification of the star is G2 Ib, here G suggests that class of the star, and Ib suggest that it is supergiant star. By the help of this we can estimate the absolute magnitude of the star using H-R diagram
It is clear from the figure that the absolute magnitude of the star is -7
Apparent magnitude of the star is give as
Plugging the values in the above equation
(d)
The classification of the star is M5 III, here G suggests that class of the star, and III suggest that it is giant star. By the help of this we can estimate the absolute magnitude of the star using H-R diagram
It is clear from the figure that the absolute magnitude of the star is 0
Apparent magnitude of the star is give as
Plugging the values in the above equation
(e)
The absolute magnitude of the white dwarf is always greater or equal to 10.
Apparent magnitude of the star is give as
Plugging the values in the above equation
Thus, it is clear that, brightest star in apparent magnitude is a, most luminous absolute magnitude star is c, largest star is c because it is a supergiant star, and farthest away star is d.
Conclusion:
- The brightest star is a.
- The most luminous star in absolute magnitude is c.
- The largest star is c.
- The farthest away star is d.
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