Which is NOT needed to determine individual masses in a binary star system?
A) the distance to the binary system
B) the plane of the orbit of the two stars
C) the relative sizes of the orbits of the two stars
D) the absolute magnitude of at least one star

Question

Quizplus · Accepted Answer

The absolute magnitude of at least one star is not needed to determine individual masses in a binary star system. The distance to the binary system is needed to determine the scale of the system and the relative sizes of the orbits of the two stars are needed to determine the ratio of the masses. The plane of the orbit of the two stars is needed to determine the inclination of the orbit, but this can be determined through spectroscopic observations of the orbital motion. However, the absolute magnitude of at least one star is not needed for any calculations related to determining the masses of the stars in a binary system.

Which Is NOT Needed to Determine Individual Masses in a Binary