Star collision helps solve 16-year-old mystery of the Blue Ring Nebula – CNET


NASA/JPL-Caltech/R. Hurt

Take a moment from this hellish year to imagine that a small star has been orbiting our sun. After eons, the two stars collide. The chaotic smash leaves behind a star and a mesmerizing blue cloud of dust and gas, a nebula, spills out into the cosmos. The cloud extends to a distance of about 13 light-years, enough to engulf 10 solar systems stacked end to end. 

While such a fate doesn’t await our sun (though it is 2020, so…), that exact scenario may have occurred a few thousand years ago at TYC 2597-735-1, a star that lies more than 6,000 light-years away from the 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 by how it came to be.

“Every time we thought we had this thing figured out 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-based 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 decommissioned 10 years later, studied the universe in ultraviolet light. It spotted an ultraviolet ring around TYC 2597-735-1 in 2004. To help visualize the cloud, researchers can color it in. The image below shows UV light displayed in blue and a faint pink ring that circles the debris, signifying visible light. The bright yellow ball at the center is TYC 2597-735-1.  

blue-ring-nebulablue-ring-nebula

Our view of the Blue Ring Nebula from Earth produces this stunning image, with UV light artificially colored blue and visibile light pink. Astronomers believe they’ve worked out its strange 3D geometry.


NASA/JPL-Caltech/NASA/JPL-Caltech/M. Seibert (Carnegie Institution for Science)/K. Hoadley (Caltech)/GALEX Team

With the help of Hawaii’s W. M. Keck Observatory, the Palomar Observatory near San Diego and space-based telescopes like NASA’s retired Spitzer, researchers began to establish some facts about the cloud. Observations in different wavelengths of light and computer modelling helped tell the full story and explain the Blue Ring’s origin.

It involves a star about the size of our sun gobbling up a smaller star in a stellar merger. The sun-like star began to balloon, growing big enough to capture the smaller star in its gravity. The two danced, gravitationally bound, for years and as the smaller star leaned in closer, it began to tear parts of its larger dancing partner away, creating a disk of gas that wrapped up the pair. When the smaller star was finally consumed, a ton of energy sliced through the gaseous disk and pushed it out as two cone-shaped clouds.

Because the Blue Ring Nebula directly faces the Earth, we see the cone clouds as a grand ring across the sky. It’s kind of like looking at an ice cream cone. If you hold the cone up to your eye horizontally (a bad idea), all you can see is a ring of ice-cream at the top (before it slips off onto the ground.) Ultraviolet light is given off by hydrogen atoms being heated up in the cone.   

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

Astronomers are also excited because they’ve caught the merger process at the most opportune time. Don Neill, a Caltech research scientist and co-author on the paper, likened it to catching a baby’s first steps in a Caltech release. “If you blink, you might miss it,” he said. It’s the first time researchers have been able to see a merger system like this that isn’t  shrouded in extreme amounts of dust, obscuring the star at its center.

In a few hundred thousand years, the Blue Ring Nebula will have faded away, as if it was never there. Perhaps we can say the same about 2020 in a few months.