Question

A galaxy of absolute magnitude of −20 is at a distance of 100 kpc. Would it be visibleto
the naked eye?

Answer 1

Answer on question #54989, Physics / Astronomy — Astrophysics

Question A galaxy of absolute magnitude of 20 is at a distance of 100 kpc. Would it be visible to the naked eye?

Solution The apparent magnitude $m$ is connected to absolute one $M$ as

$m=M+5((\log_{10}D_{L})-1)=-20+5((\log_{10}100000)-1)=0$

This magnitude is enough to see it with naked eye.