You Discover a Binary Star System in Which One Star

question 106

Multiple Choice

You discover a binary star system in which one star is a 15 MSᵤn main-sequence star and the other is a 10 MSᵤn giant.How do we think that a star system such as this might have come to exist?

• A)The giant must once have been the more massive star,but is now less massive because it transferred some of its mass to its companion.
• B)Although both stars probably formed from the same clump of gas,the more massive one must have had its birth slowed so that it became a main-sequence stars millions of years later than its less massive companion.
• C)The two stars probably were once separate,but became a binary when a close encounter allowed their mutual gravity to pull them together.
• D)The two stars are simply evolving normally and independently,and one has become a giant before the other.