need help. Define absolute magnitude and apparent magnitude.?

Question

Define absolute magnitude and apparent magnitude. Why do some stars with absolute magnitudes much greater than the sun have much smaller apparent magnitudes?

Answer 1

Absolute magnitude is the apparent magnitude an object would have if it were at a standard luminosity distance away from us in the absence of intrastellar extinction. It allows overall brightness of objects to be compared regardless of distance.

Answer 2

Its a matter of how bright a star appears to us on earth, compared to how bright it really is. How bright it really is would have to have some standard way to measure brightness, since stars are at all distances from earth so we can't use how bright they appear to be as a true measurement.

Apparent magnitude is how bright a star appears to us on earth.
Absolute magnitude is how bright a star would be at a fixed distance (usually 10 parsecs is the distance used).

So a star could be very bright and therefore have a bright absolute magnitude but be so far away from earth that the apparent magnitude is very dim.

Answer 3

Apparent magnitude is how bright the star looks in our sky.

Absolute magnitude is how bright a star would look in our sky if it were 10 parecs (32 light years) away.

If a star is more than 10 parsecs away, it will have an apparent magnitude dimmer than its absolute magnitude. If the star is less than 10 parsecs away it will have an apparent magnitude brighter than its absolute magnitude. The Sun for example has an apparent magnitude MUCH brighter than its absolute magnitude.

Answer 4

How about you look at your lecture notes and workout how to do this rather than getting other people to do it for you, which is - oh yeah CHEATING. The relationship between apparent magnitude and absolute magnitude is well known so you could just google it.