Instituto de Astrofísica e Ciências do Espaço

NGTS-39 b: a 58 d transiting warm Jupiter in an eccentric orbit

I. Apergis, D. Bayliss, S. Ulmer-Moll, S. Gill, T. Rodel, M. Battley, P. Benni, A. Bieryla, J Blake, A. Bonfanti, F. Bouchy, E. M. Bryant, M. Burleigh, S Carlier, S. Casewell, H. Chakraborty, A. Claringbold, K. A. Collins, B. Davies, X. Dumusque, T Edkins, F. Eeles-Nolle, J. A. Egger, J. Fernández Fernández, M. A. F. Keniger, P. Figueira, M. R. Goad, G Harvey, F. Hawthorn, M. J. Hobson, M. Houelle, G. Isopi, T Jestin, A. Kendall, M. Lendl, D. A. Lewis, I. Lockley, F. Mallia, J. McCormac, M. A. Mitchell, L. Mignon, H. P. Osborn, A. Psaridi, A Romanec, S. Saha, A Sedgley, S. G. Sousa, N. Thomas, S. Udry, C. A. Watson, R. G. West, T. Wilson, P. J. Wheatley, J Williams, A Zapparata, K Zielinski

Abstract

We report the discovery and characterization of NGTS-39 b (TIC 453147896 b), a warm Jupiter transiting a Sun-like star on a 58.2 d, eccentric (e = $0.386 \pm 0.019$ ) orbit. NGTS-39 b was first identified from a Transiting Exoplanet Survey Satellite single transit event, and subsequently confirmed with NGTS photometry and radial velocity measurements from CORALIE and HARPS. The host star is a bright ( $T_{m a g}$ = 11.02) F9 dwarf with effective temperature of T_eff = $6053_{- 30}^{+ 67}$ K. NGTS-39 b is a Jupiter-sized gas giant with a radius of $1.088 \pm 0.012$ R_J and a mass of $1.467 \pm 0.081$ M_J. 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 $\dot{γ} = - 17.75$ 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 P> 50 d orbiting bright stars.

Keywords
planets and satellites: detection / planets and satellites: individual: TIC-453147896 b / techniques: photometric / techniques: radial velocities

Monthly Notices of the Royal Astronomical Society
Volume 550, Issue stag1271, Page 17
2026 August

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