Two stars – A and B, with luminosities 0.5 and 4.5 times the luminosity of the
Sun, respectively – are observed to have the same apparent brightness. Which star
is the more distant, and by how much?
Stellar flux is the stellar luminosity divided by the surface area of the imaginary sphere it is situated in.
Since both of them are of same apparent brightness,
`1 = (0.5/4.5)xx(d_B^2/d_A^2)`
So, `(d_B/d_A)^2 = 9`
B must be three times farther away than A.