Using NASA’s Chandra X-ray spacecraft, astronomers have witnessed a distant, Jupiter-size world “shrinking” as its host star bombards it with heavy radiation.
The extrasolar planet, or “exoplanet,” is named TOI 1227 b and is a cosmic baby at just 8 million years old (remember, Earth is around 4.5 billion years old). And, incredibly, the world orbits its star at a distance of just 8.2 million miles, a fraction of the distance between the sun and Mercury, with a year that lasts just 28 days. This proximity means the star, named TOI 1227 and located around 330 light-years away, is blasting the planet with powerful X-rays.
This radiation is stripping the exoplanet’s atmosphere away; in fact, the atmosphere of TOI 1227 b is likely to be completely gone in around 1 billion years. This will reduce the exoplanet to nothing more than a small, rocky and barren core.
The team behind this research estimates TOI 1227 b will have ultimately lost the equivalent of two Earths’ worth of mass by the conclusion of its transformation. As of now, the world has a mass around 17 times that of Earth’s.
“It’s almost unfathomable to imagine what is happening to this planet,” Attila Varga, study team leader and a researcher at the Rochester Institute of Technology (RIT), said in a statement. “The planet’s atmosphere simply cannot withstand the high X-ray dose it’s receiving from its star.”
While this exoplanet’s parent star is less massive than the sun (with about 10% the mass of our star) and is cooler and fainter in optical light, it is actually brighter than our star in X-rays.
“A crucial part of understanding planets outside our solar system is to account for high-energy radiation like X-rays that they’re receiving,” team member and RIT scientist Joel Kastner said in the statement. “We think this planet is puffed up, or inflated, in large part as a result of the ongoing assault of X-rays from the star.”
The team used Chandra to determine just how much X-ray radiation is roasting TOI 1227 b. The researchers then used computer modeling to assess the impact of this radiation on the exoplanet and its atmosphere. This revealed that roughly every two centuries, the world loses the equivalent of Earth’s entire atmosphere from its own atmosphere.
“The future for this baby planet doesn’t look great,” Alexander Binks, a study team member and researcher at Eberhard Karls University of Tübingen, said in the statement. “From here, TOI 1227 b may shrink to about a tenth of its current size and will lose more than 10 percent of its weight.”
The researchers estimated the age of TOI 1227 b using estimates of its host star’s velocity through space and comparing them with the speed of nearby stellar populations with known ages. The team also compared the surface brightness of TOI 1227 with models of stellar evolution.
TOI 1227 b stands out from other exoplanets aged less than 50 million years because, among the set, it seems to have the longest year and a host star with the lowest mass.
The team’s research has been accepted for publication in The Astrophysical Journal and appears as a preprint on the repository site arXiv.
