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Contact Binaries II

August 16, 2012

Family dynamics are complicated. And that’s especially true of a star system in Draco, the dragon. One or two stars in the system may be driving two more into each other’s arms.

RZ Draconis is more than 1700 light-years away, so it’s far too faint to see with the eye alone. And even with a telescope, the system looks like a single pinpoint of light. But careful measurements of the system’s light reveal that it’s more than just a single star.

The two largest stars of RZ Draconis are so close together that they’re almost touching. In fact, the gravitational attraction between them is so strong that each star bulges out toward the other.

Observations over many years show that the stars may be moving closer together. If so, that could be the influence of one or two other stars in the system. There’s at least one other star, and some observations suggest there are two more.

These stars are much smaller and cooler than the system’s two big stars. Yet their gravitational influence could rob the close-together pair of momentum, causing the stars to spiral closer together. Eventually, they may touch each other, and even trade the gas in their outer layers. In essence, that would create two stellar cores surrounded by a single envelope of hot gas. In time, they could even merge to form a single star — an event that would really stir up the family dynamics.

More about stars that reach out and touch each other tomorrow.

Script by Damond Benningfield, Copyright 2012


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