The stellar collision helps solve the 16-year mystery of the Blue Ring Nebula

Take a moment from this hellish year to imagine a small star orbiting our sun. After eons, the two stars collide. The chaotic disaster leaves behind a star and a fascinating blue cloud of dust and gas, a nebula, pours into the cosmos. The cloud spans a distance of about 13 light years, enough to engulf 10 solar systems stacked from end to end.

Even if such a fate does not await our sun (although it is 2020, so …), that exact scenario may have occurred a few thousand years ago at TYC 2597-735-1, a star lying at more than 6,000 lights. . years away from Earth. Since the discovery of the star and its intriguing blue ring by NASA’s Galaxy Evolution Explorer space telescope in 2004, astronomers have been puzzled as to how it came about.

“Whenever we thought we understood this, something would tell us ‘No, that’s not right,'” said Mark Seibert, an astrophysicist at the Carnegie Institution for Science and co-author of a new study published in the journal Nature on Wednesday.

Using data from the telescope, also known as GALEX, and a suite of other ground and space telescopes to study the so-called Blue Ring Nebula in greater detail, the team of astronomers believe a stellar collision may have created the cosmic oddity.

GALEX was launched in 2003 and, before being shut down 10 years later, studied the universe under ultraviolet light. It spotted an ultraviolet ring around TYC 2597-735-1 in 2004. To help visualize the cloud, researchers can color it. The image below shows the UV light displayed in blue and a faint pink ring surrounding the debris, indicating visible light. The bright yellow ball in the center is TYC 2597-735-1.

With the help of Hawaii’s WM Keck Observatory, Palomar Observatory near San Diego, and space telescopes like NASA’s retired Spitzer, researchers have begun to establish some facts about the cloud. Observations in different wavelengths of light and computer modeling helped to tell the whole story and explain the origin of the Blue Ring.

It involves a star the size of our sun devouring a smaller star in a stellar merger. The sun-like star began to swell, becoming large enough to capture the smallest star in its gravity. The two danced, gravitationally bound, for years and as the smaller star got closer, it began tearing away parts of its larger partner, creating a disk of gas that enveloped the pair. When the smaller star was finally consumed, a ton of energy cut through the gaseous disk and pushed it out like two cone-shaped clouds.

As the Blue Ring Nebula faces the Earth directly, we see the conical clouds as a large ring in the sky. It’s a bit like looking at an ice cream cone. If you hold the cone at eye level horizontally (a bad idea), all you can see is an ice cream ring at the top (before it slides to the ground). Ultraviolet light is emitted by the hydrogen atoms which are heated in the cone.

The animation at the beginning of the article highlights the 3D structure of the nebula in impressive detail by swinging the cloud and giving us a better angle. (You may also notice an optical illusion where it appears that the two cones are moving towards each other, instead of rotating around the central star.)

Astronomers are also thrilled because they caught the merger process at the right time. Don Neill, a research scientist at Caltech and co-author of the article, likened it to capturing a child’s first steps in a version of Caltech. “If you blink, you might lose it,” he said. It is the first time that researchers have been able to see a fusion system like this that is not wrapped in an extreme amount of dust, obscuring the star at its center.

In a few hundred thousand years, the Blue Ring Nebula will have vanished, as if it had never been there. Maybe we can say the same about 2020 in a few months.