Gluttonous Star May Hold Clues to Planet Formation
In 1936, astronomers observed signs that the young star FU Orionis had begun gobbling material from its surrounding disk of gas and dust with a sudden voraciousness. During a three-month binge, as matter turned into energy, the star became 100 times brighter, heating the disk around it to temperatures of up to 12,000 degrees Fahrenheit. The brightening is the most extreme event of its kind that has been confirmed around a star the size of the sun, and may have implications for how stars and planets form. The intense baking of the star's surrounding disk likely changed its chemistry, permanently altering material that could one day turn into planets. FU Orionis is still devouring gas to this day, although not as quickly.
Visible-light observations of FU Orionis, which is about 1,500 light-years away from Earth, in the constellation Orion, have shown astronomers that the star's extreme brightness began slowly fading after its initial 1936 burst. But to understand the relationship between the star and the surrounding disk, and to find out what the star was still snacking on, astronomers combined infrared data from NASA's Spitzer Space Telescope and the Stratospheric Observatory for Infrared Astronomy (SOFIA), the world's largest airborne observatory, which is jointly owned by NASA and the German Aerospace Center. They found that FU Orionis had continued its ravenous snacking after the initial brightening event, eating the equivalent of 18 Jupiters over the next 80 years. They also predict that FU Orionis will have run out of hot material to nosh on within a few hundred years. At that point, the star will return to the state it was in before the dramatic 1936 brightening event.