Astronomers using NASA’s Transiting Exoplanet Survey Satellite (TESS) have discovered a Jovian planet orbiting the M4-type dwarf TOI-5205. Their paper will be published in the Astrophysical Journal Letters.
“M dwarfs (red dwarfs) are the most common type of stars in the Milky Way Galaxy, and host a higher number of planets on average compared to F-, G-, or K-type stars,” lead author Dr. Shubham Kanodia, an astronomer at Caltech, and his colleagues wrote in their paper.
“Yet due to their lower stellar (and disk) masses — and associated slower formation time scales — gas giants are expected to be infrequent around M dwarfs.”
“New discoveries from TESS have helped find numerous gas giants around M dwarfs despite their rarity, by observing millions of M dwarfs that are also bright enough for radial velocity mass measurements of transiting planet candidates.”
“Despite the enhanced detection signatures, the sample of confirmed transiting gas giants with precise mass measurements around M dwarfs consists of only less than 10 planets.”
“All of these transiting gas giants around M dwarfs orbit early M host stars, most of which are also metal-rich stars.”
The newly-discovered gas giant orbits TOI-5205, an M4-type star located some 283 light-years away in the constellation of Vulpecula.
Also known as TIC 419411415, the star is approximately 39% the size and the mass of the Sun.
“TOI-5205 sits near the eponymous ‘Jao gap,’ which is the transition region between partially and fully-convective M dwarfs,” the astronomers explained.
Named TOI-5205b, the new planet is only 1.03 times larger than Jupiter and 1.08 times as massive.
“TOI-5205b has one of the highest mass ratio for M dwarf planets with a mass ratio of almost 0.3%, as it orbits a host star that is just 0.39 solar masses,” the researchers noted.
To confirm the planetary nature of TOI-5205b, they used data from TESS and several ground-based telescopes.
“TOI-5205b has a large transit depth of 7%, which makes it an excellent candidate for transmission and emission spectroscopy, both from the ground (high-resolution) and space (Webb) telescopes,” they wrote.
“Atmospheric characterization could help constrain the metallicity of the planet and could offer clues about their formation history.”
“The large sample of M dwarfs being observed by TESS is already improving our understanding of planet formation around M dwarfs,” they added.
“While the first few discoveries were limited to the early M dwarfs, we are now starting to find that it is indeed possible to form these gas giants around mid-M dwarfs.”
“As we go from a sample of these planets around solar-type stars to mid-M dwarfs, there is a unique opportunity to study planet formation at its extremes, spanning more than a 2x range in stellar mass, and 100x in luminosity.”
Shubham Kanodia et al. 2022. TOI-5205b: A Jupiter transiting an M dwarf near the Convective Boundary. ApJ, in press; arXiv: 2209.11160
Source link: https://www.sci.news/astronomy/jupiter-sized-exoplanet-toi-5205b-11239.html