Great Eruption of Eta Carinae, a massive star some 7,500 light-years away that suddenly lit up the night sky for a decade beginning in 1838 is one of the most studied objects in the Milky Way. But it continues to puzzle astronomers.

n explosion in space first seen in the 19th century was apparently colder than before thought, throwing a new mystery into what may have triggered it, researchers say.

The cosmic eruption came from Eta Carinae, a star about 7,500 light-years away from Earth that is one of the most massive stars in our Milky Way galaxy. It blazed into ultra-brightness in 1838, becoming the second-brightest star in the sky for 10 years in a rare celestial outburst later dubbed the "Great Eruption." The star later dimmed, and is now not even in the top 100 list of brightest stars.
"Eta Carinae is probably the most studied object in our galaxy," said  Armin Rest, an astrophysicist at theSpace Telescope Science Institute in Baltimore and the study's lead author.

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