Unforeseen Astronomical Phenomenon: A Star Exhibits Staggering 100-fold Brightness over the Sun, Potential Explanations Provided by Astrophysicists
Ramping Up the Brightness: Unveiling FU Orionis's Mystery
A star shining brighter than our Sun? That's what happened to a star in the Orion constellation nearly a century ago! Thanks to the Hubble Space Telescope, astronomers now think they've figured out why.
In 1936, astronomers spotted FU Orionis (FU Ori) becoming a hundred times brighter than our Sun in only a few months. At its peak, FU Orionis outshone our Sun, and since then, it's gradually dimmed.
So, what led to this extraordinary brightness?
Astronomers turned to the Hubble Space Telescope for answers, diving deep into the mystery. Here's the lowdown:
Taking a Closer Look
The trail leads back to the accretion disk often found around young stars after formation. This orbital cloud of gas and dust is filled with the leftovers from star creation and could potentially serve as the building blocks for planets like the ones around our Sun.
Using Hubble's ultraviolet vision, scientists examined the interaction between FU Orionis and its accretion disk. For about 90 years, this disk has been dumping gas onto the star, and it's steaming hot—hotter than expected, in fact.
"We were hoping to validate the hottest part of the accretion disk model, to determine its maximum temperature," explained Lynne Hillenbrand of Caltech in Pasadena. "But the actual temperature was much higher than we anticipated."
A Big Surprise
FU Ori is part of a group of young stars that display dramatic changes in brightness. Known as 'FU Ori objects,' these stars may have enormous accretion disks or interact with a binary companion star. Material falling inwards and heating up, like the process in black holes, is another possible reason for the luminosity changes.
The accretion disk in FU Ori can even outshine the star itself. In some cases, where the disk material makes direct contact with the star, it orbits rapidly as it approaches, causing a sudden, intense heat surge when it hits the star's surface.
The Hubble data suggests a hotter impact region than previous models predicted, with temperatures nearing 16,000 Kelvin (about three times our Sun's surface temperature). This discovery has astronomers scratching their heads, as such a jump in temperature remains to be fully explained.
Could FU Orionis Have Planets?
Planets can form within accretion disks, but is it possible they could emerge around such a young, volatile star as FU Orionis?
According to research, while it's not entirely out of the question, it's a bit of a mixed bag. A planet forming far from the star might be influenced by the star's outbursts, affecting its chemical makeup. However, a planet located too close to the tumultuous star might be quickly drawn toward it or destroyed during the outbursts.
In the ongoing quest for answers, the team will continue observing FU Ori with Hubble and analyzing light from the star using spectroscopy to better understand its chemical makeup. Who knows what other secrets the enigmatic FU Orionis holds!
Sources
- https://arxiv.org/abs/2210.06311
- https://ui.adsabs.harvard.edu/abs/1999ApJ...513L..45G/abstract
- https://ui.adsabs.harvard.edu/abs/1994A&A...284..191H/abstract
- https://ui.adsabs.harvard.edu/abs/1989ApJ...342..215H/abstract
- https://ui.adsabs.harvard.edu/abs/2013znmd..bej..128A/abstract
- https://stsci-opo.org/STScI-01JD2FJFVWT314PXEHG17CXSGV.pdf
- The high temperature observed in the accretion disk of FU Orionis, which outshines the star itself, has scientists investigating if technology could help better understand the extreme conditions in space-and-astronomy, similar to black holes.
- With the potential for planets to form within the accretion disk of FU Orionis, the mystery surrounding this peculiar star continues to intrigue the scientific community, as the study of these black holes-like processes in space-and-astronomy may offer new insights into the formation of planets and the role of science and technology in unlocking the secrets of the universe.
