![]() After the outbursts subsided, the star had changed. Light curves recorded by Herschel and others at the time showed peaks in 1837, 1843, and 1845. Pulses of light produced by the stellar eruptions wafted off into space, passing through the burgeoning clouds of dust and gas that were gathering around the spasming star. “What origin can we ascribe to these sudden flashes and relapses? What conclusions are we to draw as to the comfort or habitability of a system depending for its supply of light and heat on so uncertain a source?” Herschel would write in 1847. For a turn, Eta Carinae became the second-brightest star in the sky astronomer John Herschel (William’s son), observed the first brightening in late 1837 from South Africa, and kept track of the flare-up. The outburst lasted for two decades, from 1837 to 1858. Circling that crazy huge star is a giant companion, but it wasn’t until 1996 that a Brazilian astronomer named Augusto Damineli realized it was there.įor much of recorded astronomical history, Eta Carinae looked like just another star.īut in the early 1800’s, it began to erupt. One of its two stars is, as described in last week’s episode of Cosmos: A Spacetime Odyssey, “pushing the upper limit of what a star can be.” The star is a bulging, nuclear behemoth more than 100 times as massive than the sun and more than a million times as bright. Located 7,500 light-years away, Eta Carinae lives in the Carina nebula, in the southern sky. Other echoes are being used to solve the mystery of Eta Carinae, one of the weirdest and most tempestuous binary star systems in the galaxy. In some echoes, astronomers have deciphered details that reveal which kinds of stars exploded in the 16th and 17th centuries – information that would otherwise be lost to the cosmos, since telescopes of the time didn’t have the spectrometers needed to read the chemical inscriptions in the light. In other words, light echoes act as astronomical time machines or portals to the past. ![]() (Light echoes around RS Puppis from HubbleESA) Often, it’s delayed by centuries, arriving long after the supernova’s embers have been extinguished.Ĭalled light echoes, these ancient reverberations bear the original signatures written into light by the explosion. Because it took a more circuitous route through the cosmos, this rerouted light arrives at Earth after the light from the original explosion. If the geometry is right, some of the light zooming away from Earth might run into a cloud and end up being redirected toward us – kind of like a billiard ball bouncing off the cushion and rolling cleanly into the pocket. Not all of that light is aimed toward Earth. But supernovas explode in three dimensions, sending light in all directions. On Earth, most of the light we’d see from one of these exploding stars would have come directly here. Sometimes, this happens after an explosive event such a supernova. But instead of ricocheting off damp cavern walls, light traveling through the universe bounces off soft, dusty clouds. Just as sounds can echo, so, too, can cosmic light. In space, echoes are produced when light does the bouncing. On Earth, echoes are produced when sound waves bounce around like pinballs.
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