In a visual binary system with circular orbits, if in 20 years the two stars' position angles have shifted by 30 degrees, the pari's period must be:
A) 60 years
B) 90 years
C) 120 years
D) 240 years
E) 360 years
Answer: D
In a visual binary system with circular orbits, if in 20 years the two stars' position angles have shifted by 30 degrees, the pari's period must be:
A) 60 years
B) 90 years
C) 120 years
D) 240 years
E) 360 years
Answer: D