ESA's Gaia finds exoplanet with nuclear fusion reaction at its core

This "may be the first direct detection of a 'Gaia exoplanet.'"
Chris Young
An artist's impression of Gaia.
An artist's impression of Gaia.


The European Space Agency's (ESA's) Gaia spacecraft helped capture an exoplanet, paving the way for follow-up observations that revealed the distant planet had a nuclear fusion reaction in its core.

An international team of scientists analyzed the new data to find that the exoplanet, HD 206893 c, was brightening, suggesting it was burning deuterium for fusion.

"The discovery of HD 206893 c is a really important moment for the study of exoplanets, as ours may be the first direct detection of a 'Gaia exoplanet,'" Professor Sasha Hinkley at the University of Exeter in England explained in a press statement.

Pinpointing the location of an alien planet

The team, led by Professor Sasha Hinkley at the University of Exeter in England, discovered the exoplanet orbiting approximately 300 million miles (484 million kilometers) away from the star HD 206893, which is located about 130 light-years from Earth and is roughly 30 percent larger than our sun.

Astronomers targeted the star HD 206893 due to the fact it has an orbiting debris disk, meaning it was a good candidate system for finding exoplanets. ESA's Gaia spacecraft's instruments allow it to take exact readings of the location of stars. The astrometric data it provides can also be used to discover exoplanets due to wobbles in those stars.

The researchers followed the Gaia discovery with observations using the Very Large Telescope in the Atacama Desert of northern Chile. These confirmed the presence of the new exoplanet, HD 206893 c, which is believed to be 13 times larger than Jupiter. The researchers published a paper detailing their findings in the preprint server arXiv.

A planet with an ongoing nuclear fusion reaction at its core

The Very Large Telescope observations also allowed the researchers to analyze the light spectrum from the exoplanet's atmosphere. This shed new light on the distant planet and ultimately showed that planet HD 206893 c has an ongoing nuclear fusion reaction burning at its core. In the follow-up observations, the researchers noticed the planet was getting brighter, suggesting that its core was undergoing nuclear fusion by burning deuterium, an isotope of hydrogen that carries a neutron.

Due to its enormous size and the ongoing fusion reaction, the exoplanet could almost have been mistaken for a brown dwarf. A brown dwarf is an object that forms similarly to regular stars but doesn't have the required mass to sustain nuclear fusion. According to the researchers, the new discovery could help astronomers better distinguish between brown stars and honest-to-goodness stars in the future.

The new discovery also shows that ESA's Gaia spacecraft can be used to pinpoint exoplanets before other ground and space observatories, such as James Webb, take direct observations. In other words, ESA's Gaia mission could prove to be a valuable tool in the ongoing search for alien worlds. It's a mission that NASA recently highlighted as a priority and one that will likely be the focus of James Webb's successor.

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