Published On: Thu, Oct 20th, 2016

Violent winds collide in one of the heaviest stars in our galaxy



A revolutionary study has obtained the sharpest ever images of one of the heaviest stars in our galaxy. The images show Eta Carinae and its violent collision of winds in stunning detail, providing new information on how stars evolve and die.

Eta Carinae, is the heavyweight champion in our galaxy, shining with a power equivalent to 5, 000, 000 Suns. It was once one of the brightest stars in the sky, but it lost its luster in 1843 when it imploded in a violent supernova, ejecting much of its stellar material into space. Much of the ejected material came to form Homunculus Nebula, a double-lobed cloud of gas and dust being constantly sculpted by stellar winds.

At the heart of the nebula, another monster companion star is evaporating while it orbits Eta Carinae. They are blowing powerful outflows that are colliding between the two at a speed of 10, 000, 000 km/h. The violent outflowing winds as seen in Eta Carinae herald the end of a star’s life as a supernova, and their study provides scientists with clues about how such stars evolve and die.



The new images reveal the violent forces churning inside Eta Carinae and the Homunculus Nebula in great detail. Astronomers created the incredibly detailed and sharp images by combining infrared observations made by three different ESO telescopes.

The team used a new imaging technique, called interferometry, which combines the light from three large telescopes to obtain extremely sharp images. The new Eta Carinae observations could only have been made with the European Southern Observatory (ESO) telescopes.

The team, led by Professor Gerd Weigelt (MPIfR), combined the infrared light of Eta Carinae employing three movable 1.8-metre telescopes of the ESO’s Very Large Telescope Interferometer. Very sharp and detailed images can be obtained when the movable telescopes are located very far apart. Because of that, the final images are as sharp as if they had been observed from a giant 130-metre telescope.

Jose Groh, Professor of Astrophysics at Trinity College Dublin said:

“These are unprecedented images obtained with the ESO telescopes. We were able to zoom in and see the heavyweight champion in our Galaxy like never before. The images provide us with a front-row view of how monster stars interact with each other. The heavier star is winning for now, but the faster companion star may change the fate of the system in the future.”

Extreme physical processes occur when the powerful winds collide in Eta Carinae. In the collision region, the hot gas emits strong amounts of light. The astronomers used this light to produce the new images of Eta Carinae. By dispersing and analyzing the light from Eta Carinae, the team could determine how the gas moves in the zone where the winds collide.

In the past, it was not possible to resolve this violent collision zone, because its extension is too small even for the largest telescopes.

“Our dreams came true, because we can now get extremely sharp images in the infrared regime, ” astrophysics professor Gerd Weigelt added. “The ESO interferometer provides us with a unique opportunity to improve our physical understanding of Eta Carinae and many other monster objects.”


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