Question

5) What is the theoretical limiting visual apparent magnitude of a 200-inch telescope? PROBLEMS TO COMPLETE FOR ABSOLUTE MAGNITUDE 6) What is the absolute magnitude of a star that is 87 pc from Earth, whose apparent magnitude is +5.50? 7) What is the apparent magnitude of a star called AX2, if d= 70 parsecs and M=- 8.1? 8) What is the modulus of a star whose apparent magnitude is +4.91 and its absolute magnitude is +2.66?

Answer 1

5)

Apparent magnitude of telescope = 9 + 5 log 200 = 20.51

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6)

absolute magnitude (M) and apparent magnitude (m) and distance (d) are related as

M = m + 5 - 5 log d

so,

M = 5.50 + 5 - 5 log 87

M = 0.8

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7)

M = m + 5 - 5 log d

-8.1 = m + 5 - 5 log 70

solve for m, I got

m = - 3.875

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8)

modulus means |m - M|

so,

|m - M| = |4.91 - 2.66| = 2.25