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

Abstract

We report the discovery of NGTS-2b, an inflated hot-Jupiter transiting a bright F5V star (2MASS J14202949 - 3112074; Teff = 6478-89+94 K), discovered as part of the Next Generation Transit Survey (NGTS). The planet is in a P = 4.51 d orbit with mass 0.74-0.12+0.13 MJ, radius 1.595-0.045+0.047 RJ, and density 0.226-0.038+0.040 g cm-3; therefore one of the lowest density exoplanets currently known. With a relatively deep 1.0 per cent 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 (v sin i = 15.2 ± 0.8 kms-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.