Since its launch in 2021, the James Webb Space Telescope has not only provided a wealth of information about the early universe but has also observed several known exoplanets. Now, for the first time, the Webb Telescope has directly discovered an exoplanet that has never been recorded before.
Researchers have reported that this newly discovered gas giant planet has a mass comparable to Saturn (the second-largest planet in the solar system), approximately 30% of the mass of Jupiter, the largest planet in the solar system. It orbits a star smaller than the Sun and is located within the Antlia constellation, approximately 110 light-years away from Earth. One light-year is about 5.9 trillion miles (9.5 trillion kilometers).
According to Reuters, astronomers have discovered approximately 5,900 exoplanets since the 1990s, most of which were found using indirect methods such as the transit method, where planets passing in front of their host stars cause a slight dimming of the star’s light. To date, less than 2% of planets have been directly imaged, including the planet discovered by the Webb Telescope this time.
While this planet may be considered large in our solar system, it is actually the smallest mass planet ever captured by direct imaging methods, with a mass only about one-tenth that of the previous record holder, highlighting the high sensitivity of the Webb Telescope’s instruments.
This discovery was made possible by a French-made coronagraph installed on the Mid InfraRed Instrument (MIRI) of the Webb Telescope, which can block out the bright light from the host star, allowing the faint signals of the planet to become visible.
The research was published on Wednesday in the journal “Nature.” Anne-Marie Lagrange, a scientist at the French National Center for Scientific Research (CNRS) and the Paris Observatory, who is the lead author of the study, stated that “the Webb Telescope has opened a new observational window, allowing us to capture low-mass, distant exoplanets that were previously unobservable. This is crucial for exploring the diversity of exoplanets and understanding their formation and evolution processes.”
This newly discovered exoplanet has been named TWA 7 b, and it orbits the host star TWA 7 at a distance approximately 52 times that of the Earth to the Sun. In comparison, Neptune, the outermost planet in our solar system, orbits only about 30 times the Earth-Sun distance. Methods like the transit method used to detect planets close to their stars would not be able to discover objects so far from their host stars.
The formation of planetary systems begins with a giant gas and dust cloud called a molecular cloud collapsing under its own gravity to form a central star. The remaining material then surrounds to form a protoplanetary disk, which eventually gives rise to planets.
In this study, the planet and its host star are only about 6 million years old, considered “young” compared to the Solar System’s approximately 4.5 billion years. As a result, the system is still very hot and brighter compared to older planets. Due to the nearly top-down viewing angle, the research team was able to clearly identify the structure of the leftover protoplanetary disk, including two wide ring-shaped dust structures and a narrow ring – the new planet is located within.
Currently, researchers are still unsure about the atmosphere composition of this planet and whether it is still accreting surrounding material and growing. Future Webb observations are expected to shed light on these questions.
Although this is the smallest mass exoplanet imaged directly to date, it is still much larger than terrestrial rocky planets, which are the key targets in the search for life. Despite the powerful infrared observation capabilities of the Webb Telescope, it is still not capable of directly imaging Earth-sized planets.
“I sincerely hope that in the future, we will be able to achieve direct imaging of terrestrial planets and the search for signs of life,” said Lagrange.