TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration

Quang H. Tran; Brendan P. Bowler; Michael Endl; William D. Cochran; Phillip J. MacQueen; Davide Gandolfi; Carina Persson; Malcolm Fridlund; Enric Palle; Grzegorz Nowak; Hans J. Deeg; Rafael Luque; John H. Livingston; Petr Kabath; Marek Skarka; Jan Subjak; Steve B. Howell; Simon H. Albrecht; Karen A. Collins; Massimiliano Esposito; V. Van Eylen; Sascha Grziwa; Elisa Goffo; Chelsea X. Huang; Jon M. Jenkins; Marie Karjalainen; Raine Karjalainen; Emil Knudstrup; Judith Korth; Kristine W. F. Lam; David W. Latham; Alan M. Levine; H. L. M. Osborne; Samuel N. Quinn; Seth Redfield; George R. Ricker; S. Seager; Luisa Maria Serrano; Alexis M. S. Smith; Joseph D. Twicken; Joshua N. Winn

doi:10.3847/1538-3881/ac5c4f

TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration
Journal article, 2022

We report the discovery of two transiting planets around the bright (V = 9.9 mag) main-sequence F7 star TOI-1670 by the Transiting Exoplanet Survey Satellite. TOI-1670 b is a sub-Neptune (R-b = 2.06(-0.15)(+0.19) R-circle plus) on a 10.9 day orbit, and TOI-1670 c is a warm Jupiter (R-c= 0.987(-0.025)(+0.025) R-Jup) on a 40.7 day orbit. Using radial velocity observations gathered with the Tull Coude Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of M-c = 0.63(-0.08)(+0.09) M(Jup )for the outer warm Jupiter, implying a mean density of rho(c) = 0.81(-0.11)(+0.13) g cm(-3). The inner sub-Neptune is undetected in our radial velocity data (M-b < 0.13 M-Jup at the 99% confidence level). Multiplanet systems like TOI-1670 hosting an outer warm Jupiter on a nearly circular orbit (l(e) = 0.09(-0.04)(+0.05)) and one or more inner coplanar planets are more consistent with "gentle" formation mechanisms such as disk migration or in situ formation rather than high-eccentricity migration. Of the 11 known systems with a warm Jupiter and a smaller inner companion, eight (73%) are near a low-order mean-motion resonance, which can be a signature of migration. TOI-1670 joins two other systems (27% of this subsample) with period commensurabilities greater than 3, a common feature of in situ formation or halted inward migration. TOI-1670 and the handful of similar systems support a diversity of formation pathways for warm Jupiters.