TOI-1136 is a Young, Coplanar, Aligned Planetary System in a Pristine Resonant Chain
Creators: name: Dai, Fei
name: Masuda, Kento
name: Beard, Corey
name: Robertson, Paul
name: Goldberg, Max
name: Batygin, Konstantin
name: Bouma, Luke
name: Lissauer, Jack J.
name: Knudstrup, Emil
name: Albrecht, Simon
name: Howard, Andrew W.
name: Knutson, Heather A.
name: Petigura, Erik A.
name: Weiss, Lauren M.
name: Isaacson, Howard
name: Kristiansen, Martti Holst
name: Osborn, Hugh
name: Wang, Songhu
name: Wang, Xian-Yu
name: Behmard, Aida
name: Greklek-McKeon, Michael
name: Vissapragada, Shreyas
name: Batalha, Natalie M.
name: Brinkman, Casey L.
name: Chontos, Ashley
name: Crossfield, Ian
name: Dressing, Courtney
name: Fetherolf, Tara
name: Fulton, Benjamin
name: Hill, Michelle L.
name: Huber, Daniel
name: Kane, Stephen R.
name: Lubin, Jack
name: MacDougall, Mason
name: Mayo, Andrew
name: Močnik, Teo
name: Murphy, Joseph M. Akana
name: Rubenzahl, Ryan A.
name: Scarsdale, Nicholas
name: Tyler, Dakotah
name: Van Zandt, Judah
name: Polanski, Alex S.
name: Schwengeler, Hans Martin
name: Terentev, Ivan A.
name: Benni, Paul
name: Bieryla, Allyson
name: Ciardi, David
name: Falk, Ben
name: Furlan, E.
name: Girardin, Eric
name: Guerra, Pere
name: Hesse, Katharine M.
name: Howell, Steve B.
name: Lillo-Box, J.
name: Matthews, Elisabeth C.
name: Twicken, Joseph D.
name: Villaseñor, Joel
name: Latham, David W.
name: Jenkins, Jon M.
name: Ricker, George R.
name: Seager, Sara
name: Vanderspek, Roland
name: Winn, Joshua N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Convergent disk migration has long been suspected to be responsible for forming planetary systems with a chain of mean-motion resonances (MMR). Dynamical evolution over time could disrupt the delicate resonant configuration. We present TOI-1136, a 700-Myr-old G star hosting at least 6 transiting planets between $\sim$2 and 5 $R_\oplus$. The orbital period ratios deviate from exact commensurability by only $10^{-4}$, smaller than the $\sim$\,$10^{-2}$ deviations seen in typical Kepler near-resonant systems. A transit-timing analysis measured the masses of the planets (3-8$M_\oplus$) and demonstrated that the planets in TOI-1136 are in true resonances with librating resonant angles. Based on a Rossiter-McLaughlin measurement of planet d, the star's rotation appears to be aligned with the planetary orbital planes. The well-aligned planetary system and the lack of detected binary companion together suggest that TOI-1136's resonant chain formed in an isolated, quiescent disk with no stellar fly-by, disk warp, or significant axial asymmetry. With period ratios near 3:2, 2:1, 3:2, 7:5, and 3:2, TOI-1136 is the first known resonant chain involving a second-order MMR (7:5) between two first-order MMR. The formation of the delicate 7:5 resonance places strong constraints on the system's migration history. Short-scale (starting from $\sim$0.1 AU) Type-I migration with an inner disk edge is most consistent with the formation of TOI-1136. A low disk surface density ($Σ_{\rm 1AU}\lesssim10^3$g~cm$^{-2}$; lower than the minimum-mass solar nebula) and the resultant slower migration rate likely facilitated the formation of the 7:5 second-order MMR. TOI-1136's deep resonance suggests that it has not undergone much resonant repulsion during its 700-Myr lifetime. One can rule out rapid tidal dissipation within a rocky planet b or obliquity tides within the largest planets d and f.
description: 48 pages, 23 figures, 8 tables. Accepted to AAS journals. Comments welcome!