Using the Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a new old and warm Jupiter-like alien world orbiting a G dwarf star. The newly discovered exoplanet, named TOI-5542 b, is the size of Jupiter – about 30% more massive than the solar system’s largest gas giant. The finding is reported in a paper published Sept. 29 on the arXiv pre-print server.
TESS is surveying about 200,000 of the brightest stars near the Sun to look for transiting exoplanets. So far, it has identified nearly 6,000 candidate exoplanets (TESS Objects of Interest, or TOI), of which 256 have been confirmed so far.
Now, a group of astronomers led by Nolan Grieves of the University of Geneva in Switzerland recently confirmed another TOI monitored by TESS. They report that a transit signal has been identified in the light curve of a metal-poor G dwarf known as TOI-5542 (other designation TYC 9086-01210-1). The planetary nature of this signal was confirmed by follow-up observations with CORALIE and High Accuracy Radial Velocity Planet Searcher (HARPS) spectrographs.
“We report the discovery and characterization of the warm Jupiter TOI-5542 b. The planet was first detected by TESS as two single transit events spaced 375.6 days apart,” the researchers wrote in the paper.
The newly discovered exoplanet has a radius of about 1.01 Jupiter radii and a mass of 1.32 Jupiter masses, giving a density of 1.6 g/cm3. It orbits its parent star every 75.12 days, at a distance of 0.33 AU from it. The equilibrium temperature of the planet was estimated at 441 K, so the astronomers classified it as a warm Jupiter.
The host TOI-5542 is of spectral type G3V, has a radius of about 1.06 solar rays and is 11% less massive than the sun. The star has an effective temperature of about 5,700 K, a brightness of about 1.05 solar luminosities and is estimated to be 10.8 billion years old. The metallicity of TOI-5542 was measured and was about -0.21.
Taking into account that TOI-5542 is almost 11 billion years old, the researchers underlined that its exoplanet is therefore one of the oldest known long-term warm Jupiters and one of the few with an estimated age.
TOI-5542b is one of the oldest known warm Jupiters and it is cool enough not to be affected by inflation due to stellar incident flux, making it a valuable contribution in the context of planetary composition and formation studies. authors of the article. .
Given that TOI-5542 b has a circular orbit, the researchers noted that it is difficult to predict a formation or migration path for this planet. They assume that it probably formed through disk migration or in situ formation as other mechanisms that leave a planet in an eccentric orbit around its parent star.
Two massive Jupiter-sized exoplanets discovered with TESS
Nolan Grieves et al, An ancient warm Jupiter orbiting the metal-poor G-dwarf TOI-5542. arXiv:2209.14830v1 [astro-ph.EP], arxiv.org/abs/2209.14830
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