Sirius is a binary system with stars of very different apparent brightnesses. Si
ID: 1770976 • Letter: S
Question
Sirius is a binary system with stars of very different apparent brightnesses. Sirius A appears 7600 times brighter than Sirius B.
c) The parallax of the Sirius system is 0.379², what is the distance to Sirius? [2pt]
d) What are the absolute visual magnitudes of Sirius A and Sirius B? How do their luminosities compare with that of the Sun? [4pt]
e) The orbital period of the Sirius binary is 50 years, while the average separation of the two stars is measured to be 7.58². Furthermore, the distance from Sirius A to the center of gravity of the system is 0.45 times the distance from Sirius B to the center of gravity. Calculate the masses of these stars in solar masses. [5pt]
f) Comparing the absolute magnitudes with the masses of these stars, what types of stars do you think they are? [2pts]
Explanation / Answer
Answer c) The Parallax formula is as below:
d=1/p, where p= parallax angle in arcseconds & d= distance in parsecs.
Hence d= 1/0.3792= 6.9618 parsecs(pc).
Further 1 parsec(pc) is equivalent to 206,265 AU.
So, 6.9618 pc= 1,435,975.68 AU
Hence the answer is 1,435,975.68 AU.