Spitzer & SOFIA track birth of a solar system

Over the course of one year in 1936 to 1937 a star in the Orion constellation became 250 times brighter, increasing from a magnitude of 16 to a magnitude of 10. In one three month period the star became 100 times brighter.

The star is FU Orionis and is the first star to be observed going through this phase of growth.

Quoting Joel Green of the Space Telescope Science Institute:

“By studying FU Orionis, we’re seeing the absolute baby years of a solar system. Our own sun may have gone through a similar brightening, which would have been a crucial step in the formation of Earth and other planets in our solar system.”

Astronomers were witnessing for the first time a star’s growth in the days before the pieces of its solar system were created and in place.

The increase in brightness is attributed to the absorption of gas from the nebula surrounding it. The star got bigger and hotter.

Quoting NASA:

“The star has eaten the equivalent of 18 Jupiters in the last 80 years”

While the brightness will fade as the absorbed material cools, the mass will be retained.

The pic at the top is an illustration of observations made by Spitzer in 2005 and observations made by the Stratospheric Observatory for Infrared Astronomy, SOFIA. SOFIA uses a 747 to fly above the denser parts of the Earth’s atmosphere to make observations. See inset pic.
Again quoting NASA:

“The recent measurements provided by SOFIA inform researchers that the total amount of visible and infrared light energy coming out of the FU Orionis system decreased by about 13 percent over the 12 years since the Spitzer observations. Researchers determined that this decrease is caused by dimming of the star at short infrared wavelengths, but not at longer wavelengths. That means up to 13 percent of the hottest material of the disk has disappeared, while colder material has stayed intact.”

In 1970 and again in 2019 two FU Orionis like eruptions were observed, giving rise to the name ‘FUOr’s’ as a description.

It’s amazing to realize that as much as we understand and control the things in our world, we know so little about the larger world around us.