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Meet The Blazing Star In The Milky Way That Just Won’t Die

Aug 03, 2018 09:08 PM EDT
Eta Carinae
Scientists observe light echoes to uncover new clues on the Eta Carinae explosion 170 years ago. The photo features the artist's conception of the powerful blast wave.
(Photo : Gemini Observatory | AURA | NSF | Artwork by Lynette Cook)

The explosion that rocked Eta Carinae in the 1840s was nearly as powerful as a supernova explosion. Amazingly, the star survived.

Eta Carinae is the most luminous star in the Milky Way, and its near annihilation over a century ago is still subject of study. Until now, 170 years later, scientists puzzle over the eruption and the mysterious reason behind it.

Light Echo Unveils New Clues

It's impossible to backtrack and get a glimpse of the explosion, but scientists have found another way to get more information by observing what's known as "light echoes." This phenomenon is when the light emanating from the explosion bounces off interstellar dust and arrives on Earth much later.

The light echo from the Eta Carinae explosion is only just making its way to Earth.

One of the astronomers who led the research is Nathan Smith of the University of Arizona, who calls light echoes "the next best thing to time travel."

"They give us a chance to unravel the mysteries of a rare stellar eruption that was witnessed 170 years ago, but using our modern telescopes and cameras," Smith explains in a report from the Gemini Observatory, adding that the data from the event can be compared to the nebula created from the blast.

This is a valuable piece of knowledge to pursue, he points out, as it's an event that has not occurred since then in the Milky Way galaxy.

The team used the Gemini South telescope from the Gemini Observatory as well as other telescopes in Chile to study the blast and its echoes.

Trio Of Stars May Be The Blast's Origin

By analyzing the wayward light, astronomers discovered that material expanded from the blast up to 20 times faster than they expected, according to NASA.

The speed is comparable to the fastest material ever ejected from a supernova explosion. It's strange to witness from dying stars, as these often produce very slow, gentle winds.

Due to the new findings documented in a pair of papers in the Monthly Notices of the Royal Astronomical Society, the astronomers suggest that the explosion may be borne from a tussle among three stars. In a violent explosion, the Eta Carinae may have devoured one of its siblings, spitting out material 10 times the mass of the sun. This mass eventually became the dumbbell-shaped gas cloud called Homunculus that's still seen in modern images.

"We see these really high velocities in a star that seems to have had a powerful explosion, but somehow the star survived. The easiest way to do this is with a shock wave that exits the star and accelerates material to very high speeds," Smith says.

Eventually, Eta Carinae will experience a true supernova explosion and meet its end. This is due in the next half million years, potentially much sooner.

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