Astronomers using NASA’s Transiting Exoplanet Search Satellite (TESS) have discovered a new ultra-short-period exoplanet. A newly discovered alien world is nearly twice the size of Earth and orbits its star in less than a day. The discovery was reported in a paper published on the preprint server on February 12. arXiv.

To date, TESS has detected more than 7,000 candidate exoplanets (TESS Objects of Interest, or TOI), of which 417 have been confirmed. Since its launch in April 2018, the satellite has been surveying some 200,000 of the brightest stars near the Sun in search of exoplanets, ranging from small rocky worlds to gas giants.

Now, a team of astronomers led by Ryan A. Rubenzahl from the California Institute of Technology has confirmed another TOI tracked by TESS. Rubenzaal’s team reports that the transit signal identified in the light curve of the star known as TOI-1347 is planetary in nature.

“We offer USP verification and features [ультракороткоперіодичного] TOI-1347 b, a planet with an Earth radius of 1.8 ± 0.1 and an orbit of 0.85 days, was detected by photometry during the TESS mission,” the researchers wrote in a paper.

According to the study, TOI-1437 b has a radius of approximately 1.8 Earth radii and is approximately 11.1 times larger than our planet, giving it a mass density of 9.9 g/cm3.³. It takes the planet approximately 20 hours and 20 minutes to orbit its parent star. Astronomers estimate that TOI-1437 b has an equilibrium temperature of about 1,400 K as it orbits its host about 4.43 solar radii away.

The researchers noted that TOI-1437 b likely has an Earth-like composition and is currently the largest USP among those with a radius less than 2.0 Earth radii. The results also reveal that the planet has an atmosphere with a high average molecular weight. However, this needs to be further confirmed using, for example, the James Webb Space Telescope (JWST).

As for the host star TOI-1437 (also known as TIC 229747848), it is a late G-type star that exhibits strong variability. It has a radius of approximately 0.83 solar radii and a measured mass of 0.91 solar masses. The age of the star is estimated to be approximately 1.4 billion years and its effective temperature is 5464 K.

In addition to confirming that TOI-1437 b is an exoplanet, Rubenzal’s team also reported the discovery of another, smaller planet in the system. The extrasolar world, called TOI-1437 c, is slightly smaller than TOI-1437 b and has a radius of about 1.6 Earth radii. Given that they were unable to detect this planet using radial velocity measurements, the authors of the paper set an upper limit for its mass of 6.4 Earth masses.