The “Blue Ring Nebula” captured by NASA’s GALEX space telescope.
In 2004, astronomers discovered a strange object that looked like a blue eye staring in the direction of Earth in the ultraviolet wavelengths, and scientists called it the Blue Ring Nebula. Now, 16 years later, scientists finally understand the cause of the Blue Ring Nebula.
This peculiar structure was first discovered by NASA’s Galaxy Evolution Explorer (GALEX) space telescope, which was deactivated in 2013. At the center is a star with the number TYC2597-735-1.
At the time, GALEX principal investigator Chris Martin said that an interesting object had been discovered and that someone might soon find out what it was. But the more he and his colleagues looked at it in the years that followed, the less they could explain its origin.
The star at the center doesn’t have much hydrogen gas, and appears to be in the late stages of its life. But it also emits a lot of infrared light, suggesting that it is surrounded by a hot disk of dust, which is characteristic of a young star. So, says Martin, this object is as mysterious as a Sherlock Holmes case.
A recent study has finally discovered that the two red-looking rings in the image are the bases of two conical dust structures created by stellar explosives, one moving toward Earth at 400 kilometers per second and the other moving in the opposite direction at the same speed. Viewed from Earth, the two conical structures overlap, creating a ring-like structure around the central star.
The researchers said that the original image captured at the time was a rare view of the two stars not long after they merged. The timing of the observation was perfect: earlier, just after the merger, nothing would have been visible under the large amount of dust that obscured the view; later, when the nebulae had already dispersed, nothing would have been visible.
Astrophysicist Don Neill of the California Institute of Technology, one of the researchers, said that the timing of the observation was like “seeing a baby walk for the first time, blinking and possibly missing it.
The study, published Nov. 18 in the journal Nature, describes what they believe happened: A sun-like star ran out of its own hydrogen fuel and began to expand. A smaller companion star next to it began to absorb material from its surface, which gradually formed a disk around the companion star.
The smaller companion moves closer and closer to the expanding star as it orbits, and finally merges with it, exploding a large amount of material in the process. However, the disk of material around the small companion star prevented some of the outbursts from spreading, causing the outbursts to form the two conical structures mentioned above, one facing the Earth and one with its back to the Earth.
Project member Mark Seibert said, “This is unique, and it’s the only one of its kind.”
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