Question

In class we studied the above work by Leavitt. From her Fig. 1 above, if a star has period 90 days, then its maximum intensity is apparent magnitude:

(A) 11.3 (B) 12.5 (C) 15.5 (D) 18.0

Referring to the same star as the previous problem, at its minimum intensity, its apparent magnitude is:

(A) 11.3 (B) 12.5 (C) 15.5 (D) 18.0

Suppose Leavitt saw a variable star with period 40 days. In the Small Magellanic Cloud, such a variable would have its maximum intensity with apparent magnitude 12.

If you knew that a variable with this period has at its maximum intensity absolute magnitude -7, how far away is the Small Magellanic Cloud? THIS ONE IS HARD!

(A) 6,000 parsecs (B) 60,000 parsecs (C) 600,000 parsecs (D) 6,000,000 parsecs

The Andromeda Galaxy is 10 times as far away as Small Magellanic Cloud. EVEN THIS ONE IS KIND OF HARD.

Referring to the variable star in the previous problem, its apparent magnitude at maximum intensity if it were in the Andromeda Galaxy would be:

(A) 7 (B) 12 (C) 17 (D) 22

Answer 1

for question 3 and 4.

3) m = apparent magnitude

M = absolute magnitude

d = distance in parsec.

formula we will be using here is :

36) m = 12

M = -7

d = ?

using the formula :

[answer] [option B]

4) m = ?

M = -7

d = 10 times of what we have calculated above in (36) = 6,00,000 parsec.

using the formual :

[answer] [option C]