Astronomers have discovered a heavily irradiated gas giant exoplanet in close orbit and strongly misaligned around a bright star called TOI-1518.
TOI-1518 is a rapidly rotating F-type star located approximately 742 light-years away in the constellation Cepheus.
Also referred to as TIC 427761355 and BD + 66 1610, it is almost twice the size and more massive than the Sun.
The new planet TOI-1518b is a swollen gas giant about 1.9 times the size of Jupiter.
It orbits its mother star once every 1.9 days at a distance of 0.04 AU (astronomical units).
“The new planet belongs to the category of the super-hot Jupiters, which have equilibrium temperatures above 2000 K,” said Yale University astronomer Samuel Cabot and his colleagues.
âMany super-hot Jupiters contain vaporized metals, both neutral and ionized, in their upper atmosphere. “
“These metals and molecules containing them are recognized as strong sources of opacity in optical and near ultraviolet regions.”
TOI-1518b was first identified as a candidate exoplanet in transit in photometric data from NASA’s Transiting Exoplanet Survey Satellite (TESS).
The planet’s presence was then confirmed using high-resolution optical transmission spectra from the EXtreme PREcision Spectrometer (EXPRES) on the Lowell Discovery Telescope.
Additionally, Cabot and his co-authors detected iron vapor in the atmosphere of TOI-1518b.
âTOI-1518b is highly inflated, which makes it suitable for intensive atmospheric characterization,â they said.
“The equilibrium temperature of TOI-1518b (2492 K) is in the regime where the planet could exhibit thermal inversion.”
âThis, combined with the brightness of the host star, makes TOI-1518b an attractive target for tracking emission spectroscopy. “
The team’s article will be published in the Astronomical Journal.
Samuel HC Cabot et al. 2021. TOI-1518b: An ultra-hot Jupiter misaligned with iron in its atmosphere. A J, in the press; arXiv: 2108.11403