A warm Jupiter transiting an M dwarf: A TESS single transit event confirmed with the Habitable-zone Planet Finder

Abstract

We confirm the planetary nature of a warm Jupiter transiting the early M dwarf TOI-1899, using a combination of available TESS photometry; high-precision, near-infrared spectroscopy with the Habitable-zone Planet Finder; and speckle and adaptive optics imaging. The data reveal a transiting companion on an $\sim 29$-day orbit with a mass and radius of $0.66\pm 0.07{\mathrm{M}}_{\mathrm{J}}$ and $1.15_{-0.05}^{+0.04}{\mathrm{R}}_{\mathrm{J}}$, respectively. The star TOI-1899 is the lowest-mass star known to host a transiting warm Jupiter, and we discuss the follow-up opportunities afforded by a warm (${\mathrm{T}}_{\mathrm{eq}}\sim 362$ K) gas giant orbiting an M0 star. Our observations reveal that TOI-1899.01 is a puffy warm Jupiter, and we suggest additional transit observations to both refine the orbit and constrain the true dilution observed in TESS.

24 pages, 5 figures, 3 tables, published in AJ