• Q
9 If we discover a type 1a supernova in a distant galaxy that at its brightest has an apparent
magnitude of 17, how
far away is the galaxy? (Assume the supernova has an absolute magnitude of -19.)
•a.1.6 Mpc.
•b.16 Mpc
•c.160 Mpc
•d.1600 Mpc
•e.16000 Mpc
•
•Using
the distance modulus formula, d(pc) = 10(m-M+5)/5 we can do this. m=17, M=-19, so d(pc) = 108.2 = 1.6x108 pc, which is 160 Mpc.