Alien exoplanet 40 times larger than Earth may be the leftover nucleus of a gas giant
A weird exoplanet 40 times larger than Earth orbiting a star 730 light-years away could be the exposed core of a Jupiter-like gas giant, scientists claim
- An exoplanet called TOI 849 b orbits its star every 18 hours – a very fast year
- The gases surrounding the core are thought to have been removed by proximity
- But it may also have hit another planet, or it may never have managed to capture the gases
An exoplanet orbiting a star 730 light-years away may actually be the surviving core of a Jupiter-like gas giant, a study claims.
Scientists suggest that TOI 849 b, which completes orbit every 18 hours, may have torn off the outer gas layer when it passed too close to its host star.
They also say it could have lost the layer on impact with another planet – or it could have been a ‘failed’ gas giant that never generated enough power to create an atmosphere.
TOI 849 b is the same size as Neptune, or about 40 times larger than Earth.
The discovery marks the first time a potential gas giant nucleus has been spotted in space, allowing researchers to peek into gas giants such as Saturn and Jupiter.
An artist’s impression of TOI 849 b, which is so close to its star that it orbits every 18 hours. It is also thought to be 1,500C on the surface of the exoplanet
The exoplanet was found this year by NASA’s Transiting Exoplanet Survey Satellite (TESS), when a drop in a star’s brightness indicated its presence.
By analyzing the amount of light it blocked, scientists were able to calculate its size and orbit time.
They could also calculate the mass, which turned out to be 40 times that of Earth, but with a radius of just 3.4 Earths, suggesting it is very dense.
This, scientists argue, means it must be a planetary core.
“The planet has a high density and should therefore consist primarily of iron, rock and water, but only very little hydrogen and helium,” said lead author Dr. David Armstrong of the University of Warwick.
“Such a small amount of hydrogen and helium is really amazing for such a huge planet.
The nucleus is thought to come from a gas giant like Jupiter, allowing scientists to see inside
“We would expect such an enormous mass to have accumulated large quantities when it formed.
“The fact that we don’t see those gases tells us that TOI 849 b is an exposed planetary core.”
The researchers suggested several theories of how it lost its outer layer, saying it offered a “ unique opportunity ” to study a planet’s interior.
“We have the ability to look at a planet’s core in a way that we cannot do in our own solar system,” said Dr. Armstrong.
For example, there are still big open questions about the nature of Jupiter’s core. Strange and unusual exoplanets like these give us a window into planet formation that we have no other way to explore. “
The study is published in the journal Nature.
Titans made from hydrogen and helium: what are gas giants?
The TOI 849 b exoplanet, located 730 light-years from Earth, is considered the exposed core of a gas giant.
These are large planets consisting mainly of the gases hydrogen and helium, but with a small rocky core.
In our solar system, Jupiter, Saturn, Uranus and Neptune are all considered gas giants.
Using NASA’s Kepler space telescope, thousands and many more have been discovered outside the galaxy.
The planets are thought to form during the formation of a sun, because the gravity of their rocky nuclei draw in hydrogen and helium released by the fiery sphere.