Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and several ground-based telescopes, astronomers have detected and characterized a warm Jupiter exoplanet orbiting the G-dwarf star TOI-5542.
“The first exoplanets discovered were Jupiter-sized planets with close-in orbits — with periods less than 10 days — around their host stars, known as hot Jupiters,” said Université de Genève astronomer Nolan Grieves and his colleagues from Switzerland, the United Kingdom, the United States, the Netherlands, South Africa and Chile.
“Even with a low occurrence rate o less than 1%, hot Jupiters remain one of the largest samples of known exoplanets due to the observational biases of current detection methods favoring close-in, large, and massive planets.”
“Hot Jupiters suffer from intense stellar irradiation that can deposit energy into their interiors and cause these planets to have radii larger than what would otherwise be expected based on internal structure models.”
“Hot Jupiters are also affected by powerful tidal forces that can lead to tidal locking and dampening of orbital eccentricity and the planetary rotation period, as well as intense day-night contrasts.”
“Therefore, the original properties of hot Jupiters have been significantly altered by their environment since their formation, which hinders placing constraints on planet formation and evolution models from current observations.”
“Warm exoplanets, which we define as exoplanets with 10-200 day orbital periods, provide the opportunity to better understand planet formation and evolution as their atmospheres are less altered by their host star and their orbital arrangement reflects a less extreme migrational history, as compared to close-in planets.”
The newfound warm Jupiter, TOI-5542b, is similar in size to Jupiter but is 1.32 times more massive.
The alien world orbits the G3-type star TOI-5542 once every 75.12 days.
It receives 9.6 times Earth’s insolation and has an equilibrium temperature of 441 K (168 degrees Celsius, or 334 degrees Fahrenheit).
The parent star, which is also known as TIC 466206508 or TYC 9086-1210-1, is at least 10.8 billion years old.
It is located approximately 1,154 light-year away in the constellation of Pavo.
“TOI-5542b likely has a circular orbit and more likely formed via disk migration or in situ formation, rather than high eccentricity migration mechanisms,” the astronomers said.
The planet was first detected by TESS as two single transit events 375.6 days apart.
Its planetary nature of the object was confirmed by ground-based spectroscopic and radial velocity observations from the CORALIE and HARPS spectrographs.
The third transit event was detected by the ground-based facilities NGTS, EulerCam, and SAAO.
“TOI-5542b is one of the oldest known warm Jupiters and it is cool enough to be unaffected by inflation due to stellar incident flux, making it a valuable contribution in the context of planetary composition and formation studies,” the researchers said.
The team’s paper will be published in the journal Astronomy & Astrophysics.
Nolan Grieves et al. 2022. An old warm Jupiter orbiting the metal-poor G-dwarf TOI-5542. A&A, in press; arXiv: 2209.14830
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