Using a combination of available TESS photometry; high-precision, near-infrared spectroscopy with the Habitable-zone Planet Finder; and speckle and adaptive optics imaging astronomers confirmed the planetary nature of a warm Jupiter transiting the early M dwarf TOI-1899.
TOI-1899 is an M0-type star located 419 light-years away in the constellation of Cygnus.
Also known as TIC 172370679 and 2MASS 19574239+4008357, the star has a temperature of 3,652 degrees Celsius and is much cooler than the Sun.
TOI-1899 is about 60% the size and mass of the Sun and is around 7.4 billion years old.
The newfound planet orbits the star once every 29 days at a distance of only 0.16 AU.
Designated TOI-1899b, the alien world is two-thirds the mass of Jupiter but 10% larger in radius.
TOI-1899b was detected by TESS using the transit method, which searches for stars showing periodic dips in their brightness as a telltale sign of an orbiting object crossing in front of the star and blocking a portion of its light.
The signal was then confirmed as a planet using precision observations from the HPF spectrograph.
References: Caleb I. Cañas et al, A Warm Jupiter Transiting an M Dwarf: A TESS Single-transit Event Confirmed with the Habitable-zone Planet Finder, The Astronomical Journal (2020). DOI: 10.3847/1538-3881/abac67