TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration
Latham, David W.; Quinn, Samuel N.; Cochran, William D.; Endl, Michael; Redfield, Seth; Howell, Steve B.; Kabáth, Petr; Collins, Karen A.; Ricker, George R.; Winn, Joshua N.; Jenkins, Jon M.; Skarka, Marek; Osborne, H. L. M.; Seager, S.; Livingston, John H.; Gandolfi, Davide; Nowak, Grzegorz; Fridlund, Malcolm; Grziwa, Sascha; Korth, Judith; Palle, Enric; Persson, Carina M.; Van Eylen, Vincent; Tran, Quang H.; Bowler, Brendan P.; MacQueen, Phillip J.; Deeg, Hans J.; Luque, Rafael; Šubjak, Ján; Albrecht, Simon H.; Esposito, Massimiliano; Goffo, Elisa; Huang, Chelsea X.; Karjalainen, Marie; Karjalainen, Raine; Knudstrup, Emil; Lam, Kristine W. F.; Levine, Alan M.; Serrano, Luisa Maria; Smith, Alexis M. S.; Twicken, Joseph D.
United States, Italy, Sweden, Netherlands, Spain, Japan, Czech Republic, Denmark, Germany, United Kingdom
Abstract
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 ( ${R}_{{\rm{b}}}={2.06}_{-0.15}^{+0.19}$ R ⊕) on a 10.9 day orbit, and TOI-1670 c is a warm Jupiter ( ${R}_{{\rm{c}}}={0.987}_{-0.025}^{+0.025}$ R Jup) on a 40.7 day orbit. Using radial velocity observations gathered with the Tull Coudé Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of ${M}_{{\rm{c}}}={0.63}_{-0.08}^{+0.09}$ 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 ( ${e}_{{\rm{c}}}={0.09}_{-0.04}^{+0.05}$ ) 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.