Astronomers discover new mini-Neptune exoplanet

An international team of astronomers reported the discovery of a new mini-Neptune exoplanet orbiting a nearby star, Report informs via Phys.org.

The newfound alien world, designated TOI-2018 b, is about two times larger and nine times more massive than the Earth. The finding was detailed in a paper published June 13 on the pre-print server arXiv.

NASA's Transiting Exoplanet Survey Satellite (TESS) is conducting a survey of about 200,000 of the brightest stars near the sun with the aim of searching for transiting exoplanets, ranging from small rocky worlds to gaseous giants. So far, it has identified nearly 6,700 candidate exoplanets (TESS Objects of Interest, or TOI), of which 350 have been confirmed to date.

According to the paper, TOI-2018 b has a radius of about 2.27 Earth radii and a mass of about 9.2 Earth masses, which suggests an Earth-like core with a hydrogen/helium envelope, or an ice-rock mixture. The planet orbits its host star every 7.44 days and its equilibrium temperature is estimated to be 652 K.

When it comes to the properties of the host star, it is about 40% smaller and less massive than the sun. The star, estimated to be 2.4 billion years old, has an effective temperature of 4,174 K and its metallicity was measured to be at a level of -0.58.