NGTS-1b: A hot Jupiter transiting an M-dwarf

TL;DR

The paper reports the discovery of NGTS-1b, a hot Jupiter transiting an M-dwarf, notable for being the most massive planet found around such a star, with implications for planet formation theories.

Contribution

First detection of a hot Jupiter transiting an M-dwarf, demonstrating that gas giants can form and migrate around low-mass stars similar to those around solar-type stars.

Findings

NGTS-1b is the most massive planet transiting an M-dwarf.

The planet has a radius of approximately 1.33 Jupiter radii.

The host star shows no signs of activity and is likely from the thick disk.

Abstract

We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf host ($T_{eff}=3916^{+71}_{-63}~K$) in a P=2.674d orbit discovered as part of the Next Generation Transit Survey (NGTS). The planet has a mass of $0.812^{+0.066}_{-0.075}~M_{J}$, making it the most massive planet ever discovered transiting an M-dwarf. The radius of the planet is $1.33^{+0.61}_{-0.33}~R_{J}$. Since the transit is grazing, we determine this radius by modelling the data and placing a prior on the density from the population of known gas giant planets. NGTS-1b is the third transiting giant planet found around an M-dwarf, reinforcing the notion that close-in gas giants can form and migrate similar to the known population of hot Jupiters around solar type stars. The host star shows no signs of activity, and the kinematics hint at the star being from the thick disk population. With a deep (2.5%) transit around a $K=11.9$ host, NGTS-1b will be a strong candidate to probe giant planet composition around M-dwarfs via JWST transmission spectroscopy.