This image of the star Eta Carinae, taken almost two decades ago by the Hubble Telescope, reveals something extraordinary. Though it blew up, releasing as much visible light as a supernova, the star somehow survived. Now it shines at the heart of a debris cloud.
In the mid-nineteenth century, the star's explosion made it the brightest object in the southern sky. But Eta Carinae is over 8,000 light years from Earth, which means it actually exploded back when humans still thought that fired ceramics were a major technical innovation.
Eta Carinae was the site of a giant outburst about 150 years ago, when it became one of the brightest stars in the southern sky. Though the star released as much visible light as a supernova explosion, it survived the outburst. Somehow, the explosion produced two polar lobes and a large thin equatorial disk, all moving outward at about 1.5 million miles per hour.
The new observation shows that excess violet light escapes along the equatorial plane between the bipolar lobes. Apparently there is relatively little dusty debris between the lobes down by the star; most of the blue light is able to escape. The lobes, on the other hand, contain large amounts of dust which preferentially absorb blue light, causing the lobes to appear reddish.
Estimated to be 100 times more massive than our Sun, Eta Carinae may be one of the most massive stars in our Galaxy. It radiates about five million times more power than our Sun. The star remains one of the great mysteries of stellar astronomy, and the new Hubble images raise further puzzles. Eventually, this star's outburst may provide unique clues to other, more modest stellar bipolar explosions and to hydrodynamic flows from stars in general.