If your telescope can detect stars as faint as 22 magnitude, what is the maximum
ID: 2305450 • Letter: I
Question
If your telescope can detect stars as faint as 22 magnitude, what is the maximum distance in parsecs that you can detect the following stars? Which of these could you detect in the Andromeda Galaxy (2 million light years), or in the middle of the Virgo Cluster (65 million light years)? Use the absolute magnitudes given in parenthesis. a) RR Lyrae stars (0.5 mag) b) Classical Cepheids (-5 mag) c) W Virginis Cepheids (-2 mag) d) Novae (-9 mag) e) Type I Supernovae (-20 mag) f Type II Supernovae (-18 mag)Explanation / Answer
The relation between absolute magnitude and apparent magnitude is given by:
m - M = - 5 + 5logd
re-arranging this gives:
d = 100.2(m - M + 5)
a] here, absolute magnitude is: M = 0.5
and apparent magnitude is given above to be: m = 22
therefore, d = 100.2(22-0.5+5) = 199526.23 pc.
repeat this for other stars.