The international team, led by Dr. Anne-Marie Lagrange, CNRS researcher at the Observatoire de Paris-PSL and Université Grenoble Alpes in France, detected a faint infrared source in the disc of debris surrounding TWA 7 using Webb’s Mid-Infrared Instrument (MIRI) and its coronagraph.
The source is located about 1.5 arcseconds from the star on the sky which, at the distance of TWA7, is roughly fifty times the distance of the Earth to the Sun. This matches the expected position of a planet that would explain key features seen in the debris disc.
Using the coronagraph on MIRI on 21 June 2024, the team carefully suppressed the bright glare of the host star to reveal faint nearby objects. This technique, called high-contrast imaging, enables astronomers to directly detect planets that would otherwise be lost in the overwhelming light from their host star.
After subtracting residual starlight using advanced image processing, a faint infrared source was revealed near TWA 7, distinguishable from background galaxies or Solar System objects.
The source is located in a gap in one of three dust rings that were discovered around TWA 7 by previous ground-based observations. Its brightness, colour, distance from the star, and position within the ring are consistent with theoretical predictions for a young, cold, Saturn-mass planet sculpting the surrounding debris disc.
“Our observations reveal a strong candidate for a planet shaping the structure of the TWA 7 debris disc, and its position is exactly where we expected to find a planet of this mass,” said Anne-Marie.
“This observatory enables us to capture images of planets with masses similar to those in the solar system, which represents an exciting step forward in our understanding of planetary systems, including our own,” added co-author Mathilde Malin of Johns Hopkins University and the Space Telescope Science Institute in Baltimore.
Initial analysis suggests that the object – referred to as TWA 7b – could be a young, cold planet with a mass around 0.3 times that of Jupiter (~100 Earth masses) and a temperature near 320 Kelvin (roughly 47 degrees Celsius). Its location aligns with a gap in the disc, hinting at a dynamic interaction between the planet and its surroundings.
Debris discs filled with dust and rocky material are found around both young and older stars, although they are more easily detected around younger stars as they are brighter. They often feature visible rings or gaps, thought to be created by planets that have formed around the star, but such a planet has yet to be detected within a debris disc.
Once verified, this discovery would mark the first time a planet has been directly associated with sculpting a debris disc and could offer the first observational hint of a trojan disc – a collection of dust trapped in the planet’s orbit.
TWA 7, also known as CE Antilae, is a young (~6.4 million years old) M-type star located about 111 light-years away in the TW Hydrae association. Its nearly face-on disc made it an ideal target for Webb’s high-sensitivity mid-infrared observations.
The findings highlight Webb’s ability to explore previously unseen, low-mass planets around nearby stars. Ongoing and future observations will aim to better constrain the properties of the candidate, verify its planetary status, and deepen our understanding of planet formation and disc evolution in young systems. This preliminary result showcases the exciting new frontier that Webb is opening for exoplanet discovery and characterisation.
These observations were taken as part of the Webb observing programme #3662.The results have been published today in Nature.