NGTS-2b: An inflated hot-Jupiter transiting a bright F-dwarf

TL;DR

NGTS-2b is a highly inflated hot-Jupiter orbiting a bright F-dwarf star, notable for its low density and suitability for atmospheric studies, discovered through the NGTS survey with high-precision photometry.

Contribution

This paper reports the discovery of NGTS-2b, a low-density hot-Jupiter around a bright star, using NGTS data without follow-up photometry, highlighting its potential for atmospheric and obliquity studies.

Findings

Planet has a 4.51-day orbit with low density.

Deep 1.0% transit around a bright star.

Suitable for atmospheric transmission spectroscopy and Rossiter-McLaughlin measurements.

Abstract

We report the discovery of NGTS-2b, an inflated hot-Jupiter transiting a bright F5V star (2MASS J14202949-3112074; $T_{\rm eff}$=$6478^{+94}_{-89}$ K), discovered as part of the Next Generation Transit Survey (NGTS). The planet is in a P=4.51 day orbit with mass $0.74^{+0.13}_{-0.12}$ M$_{J}$, radius $1.595^{+0.047}_{-0.045}$ R$_{J}$ and density $0.226^{+0.040}_{-0.038}$ g cm$^{-3}$; therefore one of the lowest density exoplanets currently known. With a relatively deep 1.0% transit around a bright V=10.96 host star, NGTS-2b is a prime target for probing giant planet composition via atmospheric transmission spectroscopy. The rapid rotation ($vsin$i=$15.2\pm0.8$ km s$^{-1}$) also makes this system an excellent candidate for Rossiter-McLaughlin follow-up observations, to measure the sky-projected stellar obliquity. NGTS-2b was confirmed without the need for follow-up photometry, due to the high precision of the NGTS photometry.