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The object, which the astronomers named the red square, could help solve a 20 year astronomical mystery.
Dr Peter Tuthill of the University of Sydney and Dr James Lloyd of Cornell University describe their research today in the journal Science.
"It's a bit of jewel," says Tuthill. "Everything is quite remarkably symmetrical."
Tuthill and Lloyd discovered the red square surrounding a star in the constellation Serpens, the serpent mythologically associated with the origin of medicine.
Rather than a square, they say the object is an hour-glass shaped cloud of gas and dust called a bipolar nebula.
Tuthill says the cross shape in the image represents two cone shapes placed tip to tip.
The object is bright because it is being illuminated by light from the star at its heart.
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Supernova 1987A showing the two overlapping rings. Has the source of the rings finally been identified? (Image: NASA) |
Supernovae are exploding stars, and Supernova 1987A is the only one to be caught on camera.
The image shows the exploding star is surrounded by two overlapping rings of dust and gas.
Astronomers did not expect to see these rings, says Tuthill, and are still arguing today about what they are.
Tuthill says the rings must have existed before the star exploded because they are so far out from the explosion itself.
Like a bolt of lightning, the explosion simply illuminated the rings that were previously in the dark, he says.
Tuthill thinks that these rings were from a nebula just like the red square.
To test his theory, he modelled the basic geometrical shape of the nebula in 3D and then rotated it to see would it would look like in 2D from various angles (see animation).
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This
animation shows a computer model of the basic nebula shape. At some
angles you can see two overlapping rings that relate to the supernova
image (Image: Peter Tuthill/University of Sydney) |
"It's possible that the star that blew up to make Supernova 1987A actually had a nebula around it [similar to the red square]," he says.
He's not sure whether the star at the heart of the red square will one day explode.
Either way, if the red square can help astronomers understand supernovae, Tuthill will be pleased.
"Supernovae throw their weight around and have a big influence over the evolution of the galaxy itself," he says.
Tuthill and Lloyd say the red square is a more symmetrical cousin of a red rectangle previously discovered in the 1970s.
"The red rectangle is a very, very famous nebula and it was thought to be unique," says Tuthill.
But the researchers now think there may be many more of these symmetrical structures in space.
