I have a question: assume two identical stars, but one is 10 times farther than the other from the earth. If the nearest star has a relative magnitude of 5, what is the relative magnitude of the other?
$\begingroup$
$\endgroup$
2
-
2$\begingroup$ Why can't you do this simple problem using the definition of the magnitude system and that received flux is proportional to the reciprocal of the square of the distance? $\endgroup$– ProfRobFeb 14 '18 at 20:25
-
$\begingroup$ This is a good question, but it's also one that's very easily answered by looking at any primary or secondary source. $\endgroup$– Carl WitthoftFeb 15 '18 at 14:29
Add a comment
|
$\begingroup$
$\endgroup$
As @RobJeffries mentions, you can calculate the difference from the equations which define magnitude and flux. But this particular case is even covered in the Wikipedia article on apparent magnitude:
For objects within the Milky Way with a given absolute magnitude, 5 is added to the apparent magnitude for every tenfold increase in the distance to the object.
So if the nearest star has magnitude 5, the farthest one has magnitude 5 + 5 = 10.
answered Feb 14 '18 at 22:47