•Question 1
If interstellar dust makes and RR Lyrae star look 1 magnitude fainter than it should, by how much will we
overestimate its
distance?
a.1.6
times b.3.2 times
c.1600 times d.5.2 times e.Actually we will underestimate its distance.
•
•Distance equations: m – M = -5 + 5log(d) and d = 10 (m-M+5)/5
where distance is in
parsecs
•
•True distance = 10 (m-M+5)/5 if no
dust.
•Dusty distance = 10 (m+1-M+5)/5
•Dusty distance/True Distance = 10 (m-M+6)/5 / 10 (m-M+5)/5
• = 10 (m-M+6)/5
– (m-M+5)/5
• = 10 6/5 –
5/5
• = 10 1.2-1
• = 10 0.2
• = 1.6
•