Why are observations of binary stars so important?

Answer 1

Just to reitterate what the other guys have said - one of the properties we want to know about a star is its mass. But we can't tell the mass of a star just by looking at it. But if we see something orbiting the star, we can tell what its mass is (that's also how we found out the mass of Earth, the Sun, etc.). Observations of binary stars can tell us the masses of the two stars. Then we can correlate the mass with other things we can observe, like brightness and temperature, so when we see an isolated star we can deduce what its mass must be from its other properties.

Answer 2

Hi. Ronin has the right idea. In order to understand the properties of a star you need to know its mass and brightness. Studying binary stars gives you both.

Answer 3

I'll take a stab:
It's easier to determine size and mass since you can measure their distance and orbit relative to each other.

Answer 4

hmmm. damned if I know. These homework questions are getting more difficult every day.