Question

Question 1:

a: The measured parallax angle for the star Antares as observed during Earth’s orbit
is 0.008”. Here, I’m using the definition that this angle is half of its total apparent
movement on the sky. Given this angle, calculate the distance to Antares.

b: The angular diameter of Antares has been resolved in one study, and given as 41
milliarcseconds. Using your answer to part a above, calculate its linear diameter. How
does this compare to the Sun’s?

c: Antares has an apparent magnitude in the V band of 0.96. Calculate its absolute
magnitude.

d: Given your answer to part c, what is its effective temperature?

(note: Using the values in this problem, your answer will seem incorrect, because of a
simplifying assumption that I am not asking you to correct for in the problem)

e: Based on the properties listed above, can you give a qualitative description of this
particular star? That is, overall how is it similar or different from the Sun?

Answer 1