This Is What It Looks Like When Stellar Winds Collide
published during a waning gibbous moon.
10/20/2016

Stellar Winds

Inset images showing the location of Eta Carinae and the surrounding Homunculus nebula in the larger Carina nebula. Credit: ESO/G. Weigelt

You might never have heard of the binary star system Eta Carinae. It’s kept a low profile lately, but back in the 1830’s, long before astronomers realized that there were two stars in the system, Eta Carinae was briefly one of the brightest stars in the sky.

The brightness was due to a great eruption, or rather, The Great Eruption, during which the larger of the two giant stars in the system spewed off a vast amount of gas and other stellar materials that still lingers around the star system. The debris (ten times the mass of our own Sun) formed a double-lobed nebula called the Homunculus nebula, which normally obscures the swiftly orbiting stars that illuminate the nebula from within.

Now, researchers have managed to capture a high-resolution image of the frenzied activity at the center of the star system, where the stellar winds from the two massive stars are colliding in a roiling mess of heat and radiation. The stellar winds of the stars are huge amounts of gas and solar material expelled by each star into space. Because the two huge stars are so close together, the solar winds run into each other, creating large amounts of heat and radiation as they collide.

That collision is what researchers were able to take a picture of, using telescopes here on Earth. The telescopes involved were part of the European Southern Observatory’s Very Large Telescope array. Researchers there were able to use a device called the Very Large Telescope Interferometer (VLTI) to capture Eta Carinae’s closeup, which showed them the structure of the collision.

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

Researchers are also busy looking for twins of Eta Carinae in other galaxies. They believe that these massive star systems can impact how their host galaxies develop over time.