Space is as vast as it is intriguing. Stars, planets , and black holes… you never know what you'll discover, but it always sparks questions. This time, the star is the James Webb Space Telescope , which has captured the first-ever direct image of a light exoplanet, the lightest ever observed using this technique.
The planet, named TWA 7b , orbits a star located about 110 light-years from Earth. But the most curious thing is not its location or size, but that it is enveloped in a disk of cosmic debris and dust, in the midst of planetary system formation.
An exoplanet has been discovered inside a debris disk.
The discovery, published this week in the journal Nature and led by astronomer Anne-Marie Lagrange from the Paris Observatory, was achieved thanks to the James Webb Space Telescope's MIRI instrument, equipped with a coronagraph that blocks the star's intense light to better observe its surroundings.
As detailed in the article, the team used this technology to look at the system "from above," in a pole-on orientation , which made it easier to see the dust rings with unprecedented clarity.
In that image, a light source appeared in the middle of a narrow ring , surrounded by two almost empty areas. This was already unusual. But simulations confirmed it: only a planet with very specific characteristics could form such a precise structure. The study indicates that the planet's estimated mass, close to a third of Jupiter's , perfectly matches the shape of the ring and the empty areas surrounding it.
This exoplanet has a mass similar to that of Saturn, making it the lightest planet ever captured in direct imaging.
What is this new exoplanet like?
Some very strange planets have been discovered, but this exoplanet has some curious characteristics. TWA 7b is very far from its star, about 52 astronomical units away, roughly the same distance as between the Sun and Pluto's orbit. It takes several centuries to complete one orbit . It is not a hot planet, but a cold one, with a temperature of around 47 degrees Celsius.
The researchers also considered other possible explanations for the light source. One was that it was a distant galaxy , coincidentally aligned with the dust disk. However, after analyzing the statistical probability and cross-referencing data from other observatories, they ruled this out; the possibility that it is a background galaxy located right there has only a 0,34% probability.
The computer simulations included in the study showed that the planet not only exists, but is also responsible for sculpting the ring in which it is located , creating a zone of material scarcity right in its path, as if it were a shepherd satellite clearing a path in a disk of dust.
Researchers believe that, with deeper observations from the James Webb Space Telescope , it will be possible to detect even smaller bodies, up to a quarter of the mass of Jupiter, at similar distances.
Obtaining this direct image represents a significant advance in the study of forming planetary systems, allowing scientists to observe how exoplanets interact with surrounding material, modifying the disks of dust and debris in their wake. This knowledge helps us better understand the processes that give rise to planets in the universe.
The discovery of TWA 7b demonstrates that it is possible to observe light planets in the early stages of their development, something that previously posed a major challenge for direct imaging technology.
