Question

Star A is three times as far away as Star B. What is the difference in absolute magnitudes MA − MB ?

Answer 1

The relation between the absolute magnitude (M) and the apparent magnitude (m) is given by
   
where, D is the distance of the star in parsec.
  Thus, we see that the difference in absolute magnitude is
     

Now, assuming that m_A = m_B, we have
  
Now, given D_A = 3 D_B, we have