Abstract We report the discovery and characterisation of NGTS-39 b (TIC 453147896 b), a warm Jupiter transiting a Sun-like star on a 58. 2 day, eccentric (e = 0. 386 ± 0. 019) orbit. NGTS-39 b was first identified from a TESS single transit event, and subsequently confirmed with NGTS photometry and radial velocity measurements from CORALIE and HARPS. The host star is a bright (Tmag = 11. 02) F9 dwarf with effective temperature of Teff = 6053-₃₀^+67 K. NGTS-39 b is a Jupiter-sized gas giant with a radius of 1. 088 ± 0. 012 RJ and a mass of 1. 467 ± 0. 081 MJ. Its equilibrium temperature is 519-₅^+6 K, placing it between short-period hot Jupiters and cold, Jupiter-like giants. The high orbital eccentricity and intermediate equilibrium temperature of NGTS-39 b make it a valuable test case for formation and migration models, particularly in the poorly sampled regime of long-period gas giants. The RV data show a linear trend of ̇ = -17. 75 m s−1 yr−1, which indicates the presence of an outer companion. The discovery of NGTS-39 b contributes to the small but growing population of transiting warm Jupiters with P50 days orbiting bright stars.
Apergis et al. (Mon,) studied this question.