# Answer to Question #18133 in Astronomy | Astrophysics for praveen

Question #18133

The apparent magnitude of star at distance of 100 parsec is 7. what is its absolute magnitude?

Expert's answer

The absolute magnitude is magnitude the object would have ifit was at distance of 10 parsecs.

This is 10 times closer then object is. At this distance it would have 100

times larger luminocity. The difference in magniеudes can be find as

m1-m2 = -2.5 lg(L1/L2)

Hence, its absolute magnitude is

m1 = 7-2.5 ln(100) = 7-5 = 2

This is 10 times closer then object is. At this distance it would have 100

times larger luminocity. The difference in magniеudes can be find as

m1-m2 = -2.5 lg(L1/L2)

Hence, its absolute magnitude is

m1 = 7-2.5 ln(100) = 7-5 = 2

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