Double Giant
One of the superstars of modern astronomy is a super star -- a massive star known as Eta Carinae. It's big and hot, and it's surrounded itself with a thick nebula -- a cloud of gas and dust. The nebula makes the system look like a peanut with a lacy tutu around its middle.
The cloud is so thick that it hides Eta Carinae from view -- and even concealed the fact that it probably consists of two stars, not one.
Astronomers have suspected that the system contained a second star for quite a while. For one thing, the star appeared to be too massive to exist. And for another, the system produces X-rays, which could come from collisions between "winds" from two stars. The X-rays periodically disappear for a bit, suggesting that their source was passing behind the main star.
Even so, astronomers couldn't see into the nebula with enough clarity to determine if Eta Carinae consists of one star or two.
In 2003, though, they observed the system with an orbiting telescope called FUSE. It detects a form of ultraviolet energy that comes from very hot stars.
FUSE found a strong source of ultraviolet energy inside the nebula, but it disappeared just before the X-rays did -- an indication that a second star was passing behind the more massive one.
The discovery doesn't diminish Eta Carinae's luster, though. Both stars are far more massive than the Sun, and at least one of them may end its life by blasting itself to bits as a supernova.
Script by Damond Benningfield, Copyright 2005
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