question from 2005 indepedent (1 Viewer)

[sunjet]

Star X, at a distance of 2 parsecs away from Earth, has an apparent magnitude of 1.3. The amount of energy received from star X is 8x10^-9 Wm^-2. Determine the energy you would receive from star Y at a distance of 3 parsecs if its aboslute magnitude was 1.5.

 

[helper]

Firstly determine the absolute magnitude of Y using M=m-5log(d/10)
Then find the apparent magnitude of Y at 2 parsec

Then you will use the intensity formula, I_A/I_B=100^(mb-ma)/5 to find the intensity of Y.

You then will use the inverse square law: I_Ad_A²=I_Bd_B²
To find the intensity at 3 parsec.

There quite well may be a shorter method.

 

[sunjet]

I used the brightness formula then timed it by energy.