Question

1. [5 marks] Betelgeuse (α Orionis) has been carefully examined using interferometry. In fact, in 1920 it became the first star (aside from the Sun) to have its angular size measured. A recent measurement put the value at 54.7 milliarcseconds. According to data from the Hipparcos satellite, its parallax is 5.07 milliarcseconds. This star is a red supergiant. [Hint: the values given here may not give you the same results to the questions below as you would find on the internet; you are determining these values for yourselves, internet values are not acceptable.] a. [2] Determine the distance to Betelgeuse in parsecs; also report the value in light years. b. [2] Determine the Betelgeuse’s radius in three different units: metres, solar radii, and AU. c. [1] Which planets in our solar system would be gone if Betelgeuse replaced the Sun?

Answer 1