Two planets were recently discovered near the star TOI-1453, located 250 light-years away. One of them is a fairly ordinary super-Earth, but the other turned out to be a sub-Neptune that has a record low density.
System of two interesting exoplanets
Astrophysicists have again enriched our knowledge of the cosmos with a new discovery: two small planets orbiting TOI-1453. Located about 250 light-years away from Earth in the constellation Draco, this star is part of a binary system (a pair of stars orbiting each other) and is slightly cooler and smaller than our Sun. The discovery, published in the journal Astronomy & Astrophysics, paves the way for future atmospheric studies to better understand this type of planet.
There are two planets orbiting around this star, a super-Earth and a sub-Neptune. These are types of planets that are absent in our Solar System, but paradoxically are the most common classes of planets in the Milky Way. This discovery sheds light on the configuration of the planets, which may provide valuable clues as to their formation and evolution.
Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the HARPS-N high-resolution spectrograph, the researchers were able to identify TOI-1453 b and TOI-1453 c, two exoplanets orbiting TOI-1453.
Characteristics of exoplanets
“These two planets present an interesting contrast in their characteristics,” explains Manu Stalport, an astrophysicist at the University of Liege and first author of the publication.
TOI-1453 b is a super-Earth, slightly larger than our planet and probably rocky. It completes its orbit in just 4.3 days, making it a very close planet to its star. In contrast, TOI-1453 c is a sub-Neptune, about 2.2 times the size of Earth, but with an extremely low mass of only 2.9 Earth masses. This makes it one of the least dense sub-Neptunes ever discovered, raising questions about its composition.
Transit and radial velocity
Exoplanet detection remains a challenge. The team relied on two key methods to confirm their discoveries. The transit method (TESS data) measures the size and orbital period when a planet passes in front of its parent star, causing a slight decrease in brightness.
The second method used is radial velocity measurement (HARPS-N data), which involves observing changes in the velocity of a star under the influence of the gravity of a planet orbiting it. By studying the gravitational effects of the planets on their star, the researchers were able to measure their masses and densities.
“All these observations have shown that TOI-1453 c is extremely light for its size, suggesting that it may have a dense, hydrogen-rich atmosphere or a composition dominated by water. This makes it an ideal candidate for future atmospheric research,” enthuses Manu Stalport. “Understanding their formation and evolution can provide clues about the development of planetary systems, including our own.”
Further research
Moreover, both planets orbit in a configuration close to a 3:2 resonance, meaning that for every three orbits of the inner planet, the outer planet completes almost exactly two. Such resonances are thought to be a natural consequence of orbital migration, offering clues as to how planets move and settle into their final orbits.
This discovery provides new research perspectives. Observational instruments such as the James Webb Space Telescope (JWST) can analyze the atmosphere of TOI-1453 c to determine its basic composition. If this planet has a hydrogen-rich atmosphere or a water-dominated interior, it could overturn our ideas about sub-Neptunes and their formation.
According to phys.org
