An international team of astronomers reported the discovery of a new “super-Earth” exoplanet using NASA’s Transiting Exoplanet Survey Satellite (TESS) instrument. The newly discovered alien world, designated TOI-244 b, was found to have extremely low density. The discovery was reported in an article published May 8 on the preprint server. arXiv.

TESS searches about 200,000 of the brightest stars near the Sun to look for transiting exoplanets. So far, approximately 6,600 candidate exoplanets (TESS Objects of Interest or TOIs) have been identified, of which 331 have been confirmed.

Now, a team of astronomers led by Amadeo Castro-González of the Spanish Center for Astrobiology in Madrid, Spain, has confirmed another TOI observation by TESS. They reported that the transit signal was detected in the light curve of the nearby bright early M dwarf star TOI-244 (also known as GJ 1018), which has the M2.5 V spectral type at nearly half the size and mass of the star. . The planetary nature of this signal was confirmed by radial velocity measurements with the ESPRESSO spectrograph on the European Southern Observatory’s Very Large Telescope (VLT) in Chile.

“Based on the transit signal detected from the TESS data, we conducted an intense radial velocity campaign with ESPRESSO to confirm its planetary nature, obtain a precise mass measurement, and search for additional planets,” the researchers write.

According to the study, TOI-244 b has a radius of 1.52 Earth radii and a mass of about 2.68 Earth masses, giving it a density of 4.2 g/cm.³. The planet orbits its host every 7.4 days at a distance of about 0.056 AU, and its equilibrium temperature is estimated to be about 458 K.

Based on the data obtained, Castro-González’s team classified TOI-244b as a “super-Earth”. Such planets are heavier than Earth, but do not exceed the mass of Neptune. Although the term “super-Earth” refers only to the mass of a planet, it is also used by astronomers to describe planets larger than Earth but smaller than the so-called “mini-Neptunes” (with radii between two and four Earth radii). .

The results show that TOI-244b is composed of iron and silicates in similar proportions to Earth’s. However, the planet is less dense than most super-Earths of its size. The density of TOI-244 b is also lower than Earth’s expected composition. The researchers suggest that the low density of TOI-244 b is due to the presence of a significant number of volatile elements.

“In this sense, we found that atmospheric loss processes can be very effective at removing the potential primordial hydrogen shell, but retaining high average molecular weight volatiles such as water,” the authors of the paper write.

The astronomers added that TOI-244b is an excellent target for future atmospheric studies due to its unusual properties and the possible presence of a large atmosphere.