Using the Transiting Exoplanet Reconnaissance Satellite (TESS), an international team of astronomers has discovered a warm, ancient Jupiter-like alien world orbiting a dwarf star G. The newly discovered exoplanet, called TOI-5542 b, is the size of Jupiter – about 30% larger than the largest gas giant in the solar system. The result was reported in a paper published September 29 on the arXiv server ahead of print.
TESS is surveying about 200,000 of the brightest stars near the Sun in search of transiting exoplanets. To date, it has identified nearly 6,000 candidate exoplanets (TESS Objects of Interest, or TOI), of which 256 have been confirmed to date.
Now, a group of astronomers led by Nolan Graves 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 using a CORALIE high-resolution radial velocity spectrometer (HARPS).
“We report the discovery and characterization of the warm Jupiter TOI-5542 b. The planet was first detected by TESS as two single transits separated by 375.6 days,” the researchers wrote in the paper.
The newly discovered exoplanet has a radius of about 1.01 the radius of Jupiter and a mass of 1.32 the mass of Jupiter, resulting in a density at the level of 1.6 g/cm3. It orbits its parent star every 75.12 days, at a distance of 0.33 astronomical units from it. The planet’s equilibrium temperature was estimated at 441 K, so astronomers classified it as a warm Jupiter.
The host TOI-5542 is of spectroscopic type G3V, has a radius of about 1.06 solar radii and is 11% less massive than the Sun. The star has an effective temperature of about 5700 K, a luminosity of about 1.05 solar luminosity and an estimated age of 10.8 billion years. TOI-5542’s metallicity is measured to be approximately -0.21.
Taking into account that TOI-5542 is approximately 11 billion years old, the researchers confirmed that its exoplanet is thus one of the oldest known warm Jupiter for a long time and one of the few with an age estimate.
The authors of the paper conclude, “TOI-5542b is one of the oldest known warm Jupiters and is cool enough not to be affected by inflation due to the flow of stellar events, making it a valuable contribution in the context of studies of planetary formation and formation.” .
Given that TOI-5542 b has a circular orbit, the researchers note that it is difficult to predict the formation or migration path of this planet. They hypothesize that it was likely formed by disk migration or in situ formation such as other mechanisms that likely left the planet in an eccentric orbit around its parent star.
Two massive Jupiter-sized exoplanets have been discovered using TESS
Nolan Grieves et al, a warm ancient Jupiter orbiting a metal-poor G-dwarf TOI-5542 dwarf. arXiv: 2209.14830v1 [astro-ph.EP]arxiv.org/abs/2209.14830
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