A team led by Caleb Cañas of Penn State has announced in The Astronomical Journal the discovery of the fifth Jupiter-sized planet orbiting a low-mass star. As Dr. Pamela says, you find something once, that’s interesting. You find something twice, you have a group. Now we’ve found this type of system five times. 

However, there is still a first here. The planet, TOI-1899 b, has the longest orbital period of the warm Jupiters found – about 29 days. The other four examples all orbit their host stars in less than four days. The new planet was found using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) spacecraft. The planet’s mass, radius, and orbital period were determined using the Habitable-zone Planet Finder (HPF) at McDonald Observatory, and its existence may answer some questions about planetary formation. 

As co-author Rebecca Dawson states, “Warm Jupiters like TOI-1899 b orbit surprisingly close to their star. Even though the planet’s orbital period is long compared to many other giant planets detected and characterized through the transit method, it still places the giant planet much closer to its star than we’d expect from classical formation theories. Detailed characterization of their physical and orbital properties, system architecture, and host stars—as the HPF team has done for TOI-1899 b—allow us test theories for how giant planets can form or be displaced so close to their star.”

More Information

Penn State University press release 

“A Warm Jupiter Transiting an M Dwarf: A TESS Single-Transit Event Confirmed with the Habitable-zone Planet Finder,” Caleb I. Cañas et al., 2020 Sep. 2, Astronomical Journal (preprint on arxiv.org)