# NGTS-6b: An Ultra Short Period Hot-Jupiter Orbiting an Old K Dwarf

## TL;DR

This paper reports the discovery of NGTS-6b, an ultra-short period hot Jupiter orbiting an old, metal-rich K dwarf, providing insights into the formation and evolution of such close-in gas giant planets.

## Contribution

It presents the first detailed characterization of NGTS-6b, an ultra-short period hot Jupiter, and discusses its implications for planetary formation and atmospheric evolution models.

## Key findings

- NGTS-6b has a 21.17-hour orbital period.
- The planet's mass is approximately 1.33 Jupiter masses.
- It likely lost about 5% of its atmosphere over 9.6 billion years.

## Abstract

We report the discovery of a new ultra-short period hot Jupiter from the Next Generation Transit Survey. NGTS-6b orbits its star with a period of 21.17~h, and has a mass and radius of $1.330^{+0.024}_{-0.028}$\mjup\, and $1.271^{+0.197}_{-0.188}$\rjup\, respectively, returning a planetary bulk density of 0.711$^{+0.214}_{-0.136}$~g~cm$^{-3}$. Conforming to the currently known small population of ultra-short period hot Jupiters, the planet appears to orbit a metal-rich star ([Fe/H]$=+0.11\pm0.09$~dex). Photoevaporation models suggest the planet should have lost 5\% of its gaseous atmosphere over the course of the 9.6~Gyrs of evolution of the system. NGTS-6b adds to the small, but growing list of ultra-short period gas giant planets, and will help us to understand the dominant formation and evolutionary mechanisms that govern this population.