You've never seen a star in this much detail, and you won't go blind

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Aug 27, 2017

If you missed the eclipse, there’s another star you can see, and this time you won’t need special glasses.

Red supergiant Antares, which glows with pinkish fire like the cosmic heart of the Scorpius galaxy, is on the verge of a supernova. It has expanded so much during its dying phase that the tendrils of fire on its outer layers would reach all the way to Mars if it was the star the planets in our solar system orbited. It shines visibly in the night sky from 550 light-years away. You can even see it without a telescope.

Antares is about 15 solar masses, but continues to atrophy in its pre-supernova state. Astronomers have long been baffled as to how exactly stars approaching death shed mass from their upper atmosphere so rapidly, but the ESO's Very Large Telescope Interferometer (VLTI) has produced brilliantly detailed images by zeroing in on the detail of surface motions on the stars and mapping them. It does this by creating an almost sci-fi virtual telescope by merging light from up to four individual telescopes to get the resolution of a 650-foot-wide mirror. Talk about hi-res.

“How stars like Antares lose mass so quickly in the final phase of their evolution has been a problem for over half a century,” said Keiichi Ohnaka, lead author of a study recently published in Nature. “The VLTI is the only facility that can directly measure the gas motions in the extended atmosphere of Antares—a crucial step towards clarifying this problem. The next challenge is to identify what’s driving the turbulent motions.”

VLTI map of Antares.

What Ohnaka’s team observed was gaseous turbulence in the outer atmosphere, with huge clouds of gas rising and receding. This means the presence of some new phenomenon, since it cannot be demystified by convection currents which transfer heat from the star’s core to its outer reaches.

“Convection alone cannot explain the observed turbulent motions and atmospheric extension, suggesting that an unidentified process is operating in the extended atmosphere,” he explained.

The main image of Antares (top) that has been lighting up the internet is actually a composite of images observed by the Very Large Telescope. In the trippy VLTI map above, Antares looks like a lava lamp for a reason. While the instrument was unable to take velocity measurements in the black regions, the colored areas highlight approaching material in tie-dye reds and yellows and oranges, while blues and greens show material drifting off into space.

Until we do understand what force is behind the dwindling mass of Antares and other red supergiants, the rainbow swirls of that map will make an awesome poster. 

(via The Guardian)