An international research team has seen signs of fusion in the core of a distant planet. The exoplanet orbits the star HD 206893, which is 130 light-years away and about 30 percent larger than our Sun.
The first observations of the planet were made using the Gaia space telescope. The telescope’s main task is astrometry – measuring the positions, distances and movements of stars. Through precise measurements of the movements of the stars, the telescope should also be able to detect exoplanets.
After Gaia hinted at a planet in the star system, the Gravity instrument, which is located at the Very Large Telescope in Chile, was aimed at the star. Gravity – combining measurements in near-infrared wavelengths from four telescopes – was then able to confirm the existence of the planet.
– The discovery of HD 206893 c is a big moment for the study of exoplanets, it may be the first direct observation of a “Gaia exoplanet”, says Professor Sasha Hinkley at the University of Exeter in the UK in a press release.
Using data from Gravity, the research team has also been able to see how the planet’s brightness has increased, which indicates ongoing fusion of the hydrogen isotope deuterium in the planet’s core.
«Failed Stars»
Brown dwarf stars are also called “failed stars” and are space objects that are not large enough for fusion of ordinary hydrogen to take place in their cores. They are smaller than the lightest main sequence stars, but are thought to have masses at least 13 times that of Jupiter.
Although the type of fusion found in the Sun is not possible in brown dwarf stars, fusion of the hydrogen isotope deuterium, or heavy hydrogen, can occur. The same process has now been discovered with the planet HD 206893 c, which means that it can be seen as an intermediate between the planet and “failed star”.
– Very significant
According to the scientific article, which has been accepted by the journal Astronomy and Astrophysics, the planet has a mass close to 13 Jupiter masses. The fact that the new planet is around the mass limit for when deuterium fusion is possible may affect the definition of what is an exoplanet and what is a “failed star”, according to the researchers.
The newly discovered planet is 483 million kilometers from its star, roughly the same distance from the Sun to a point between Mars and Jupiter. Further out in the star system, an even more massive object has already been discovered – the brown dwarf star HD 206893 b.
– The discovery is also very significant because it shows that we can now categorize the atmosphere of exoplanets where we already know they are, approximately at a distance two to four times the distance from the sun to Earth, says Sasha Hinkley in the press release.
The article was first published on The Technique
