TESS detects new sub-Neptune exoplanet more than three times larger than Earth – Phys.org
2025-04-23T18:59:25Z
Using NASA’s Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers have detected a new sub-Neptune exoplanet orbiting a bright G-type star. The newfound alien world, designated TOI-3493 b is more than three times larger and about …
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TESS PDCSAP light curve for TOI-3493 (gray points) for two sectors, 37 (top) and 64 (bottom), overplotted with the transiting-planet model in black. Credit: arXiv (2025). DOI: 10.48550/arxiv.2504.12884
Using NASA’s Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers have detected a new sub-Neptune exoplanet orbiting a bright G-type star. The newfound alien world, designated TOI-3493 b is more than three times larger and about nine times more massive than Earth. The finding was reported in a research paper published April 17 on the preprint server arXiv.
To date, TESS has identified more than 7,500 candidate exoplanets (TESS Objects of Interest, or TOI), of which 620 have been confirmed so far. Since its launch in April 2018, the satellite has been 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.
TOI-3493, also known as HD 119355, is a star of spectral type G1/2 V at a distance of some 315 light years away. Recently, a group of astronomers led by Priyanka Chaturvedi of the Thuringia State Observatory Tautenburg in Germany, identified a transit signal in the light curve of TOI-3493 with TESS. The planetary nature of this signal was confirmed by follow-up observations using ground-based facilities.
“In this paper, we present the discovery of TOI-3493 b, a small exoplanet with a mass less than that of Neptune,” the researchers wrote.
According to the study, TOI-3493 b has a radius of approximately 3.22 Earth radii and its mass is 8.97 Earth masses, which yields a bulk density at a level of 1.47 g/cm3. The planet orbits its host every 8.16 days and its equilibrium temperature is estimated to be some 1,102 K.
The properties of TOI-3493 b suggest that it is a water-rich alien world. The astronomers assume that it may either have a large core predominantly composed of silicates and water with a thinner hydrogen outer layer, or a smaller, denser rocky core with a thicker hydrogen envelope.
The researchers noted that TOI-3493 b has a transmission spectroscopy metric (TSM) of approximately 110. This makes it the second-most favorable target for further transmission spectroscopy studies.
“TOI-3493 b is a promising candidate for transmission spectroscopy measurements for exoplanets, placed second to HD 191939 b on the metric scale,” the authors of the paper wrote.
When it comes to the star TOI-3493, it has a radius of about 1.23 solar radii and its mass is comparable to that of the sun. The star has an effective temperature of 5,844 K, metallicity at a level of approximately 0.03 dex, and its age is estimated to be 7.3 billion years. Its rotational period of about 34 days suggests that it is an inactive star.
More information: P. Chaturvedi et al, TOI-3493 b: A planet with a Neptune-like density transiting a bright G0-type star, arXiv (2025). DOI: 10.48550/arxiv.2504.12884 Journal information: arXiv
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