The shredded remnants of the first supernova ever recorded by humans — which appeared in the sky more than 1,800 years ago and vanished within eight months — rise from the cosmic grave in a stunning new image from the National Science Foundation's NOIRLab.
Tinged blood red and swirling around an invisible center of mass, the ghostly clouds of gas are thought to be the last scraps of a star that exploded so brightly and violently that the blast was visible in Earth's nighttime skies for nearly a year in A.D. 185.
Chinese astronomers who witnessed the blast dubbed it a "guest star," as the explosion appeared suddenly where no star had been visible before and then slowly faded back into the cosmic background, according to NOIRLab (opens in new tab).
Astronomers have since linked those historic accounts to a supernova remnant named SN 185, located about 8,000 light-years from Earth near the constellations Circinus and Centaurus. Initially, researchers estimated the supernova remnant to be about 10,000 years old, based on how far the gassy scraps had traveled from the dead star's likely location. Now, however, astronomers favor another explanation: The departed star exploded much more recently (about 1,800 years ago, putting it in line with the historical accounts), and with much greater force than a typical supernova.
The most common type of supernova, known as a Type II or core-collapse supernova, results when a massive star measuring at least eight times the sun's mass runs out of nuclear fuel and crumples in on itself. The star violently expels its outer layers of gas in an enormous explosion, leaving behind colorful fireworks of irradiated gas that can stretch into space for trillions of miles.
But a rarer, more powerful type of explosion called a Type Ia supernova occurs when a large star shares a close binary orbit with a white dwarf — the small, shriveled husk of a dead star that was formerly about the size of the sun. In this case, the white dwarf siphons gas away from its larger companion until the dead star's core compresses to a critical mass, setting off a runaway nuclear reaction. These explosions are the brightest supernovas in space, and they expand much more rapidly than their Type II counterparts, according to NOIRLab.
The new supernova image, taken with NOIRLab's telescope-mounted Dark Energy Camera in Chile, further confirms SN 185's explosive past as a Type Ia supernova and could lead researchers to further clues about the ancient explosion's origins.