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

Publication date: 
Main author: 
Tran, Quang H.
IAA authors: 
Luque, Rafael
Tran, Quang H.;Bowler, Brendan P.;Endl, Michael;Cochran, William D.;MacQueen, Phillip J.;Gandolfi, Davide;Persson, Carina M.;Fridlund, Malcolm;Palle, Enric;Nowak, Grzegorz;Deeg, Hans J.;Luque, Rafael;Livingston, John H.;Kabáth, Petr;Skarka, Marek;Šubjak, Ján;Howell, Steve B.;Albrecht, Simon H.;Collins, Karen A.;Esposito, Massimiliano;Van Eylen, Vincent;Grziwa, Sascha;Goffo, Elisa;Huang, Chelsea X.;Jenkins, Jon M.;Karjalainen, Marie;Karjalainen, Raine;Knudstrup, Emil;Korth, Judith;Lam, Kristine W. F.;Latham, David W.;Levine, Alan M.;Osborne, H. L. M.;Quinn, Samuel N.;Redfield, Seth;Ricker, George R.;Seager, S.;Serrano, Luisa Maria;Smith, Alexis M. S.;Twicken, Joseph D.;Winn, Joshua N.
The Astronomical Journal
Publication type: 
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 <SUB>⊕</SUB>) on a 10.9 day orbit, and TOI-1670 c is a warm Jupiter ( ${R}_{{\rm{c}}}={0.987}_{-0.025}^{+0.025}$ R <SUB>Jup</SUB>) 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 <SUB>Jup</SUB> for the outer warm Jupiter, implying a mean density of ${\rho }_{c}={0.81}_{-0.11}^{+0.13}$ g cm<SUP>-3</SUP>. The inner sub-Neptune is undetected in our radial velocity data (M <SUB>b</SUB> &lt; 0.13 M <SUB>Jup</SUB> 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.
ADS Bibcode: 
Exoplanet astronomy;Radial velocity;Exoplanet formation;Transit photometry;486;1332;492;1709;Astrophysics - Earth and Planetary Astrophysics