Transit-Timing Variation Signature of Planet Migration: The Case of K2-24

Abstract

The convergent migration of two planets in a gaseous disc can lead to capture in mean motion resonance (MMR). In addition, pairs of planets in or near MMRs are known to produce strong transit timing variations (TTVs). In this paper we study the impact of disc-induced migrations on the TTV signal of pairs of planets that enter a resonant configuration. We show that disc-induced migration creates a correlation between the amplitude and the period of the TTVs. We study the case of K2-24, a system of two planets whose period ratio indicates that they are in or near the 2:1 MMR, with non-zero eccentricities and large-amplitude TTVs. We show that a simple disc-induced migration cannot reproduce the observed TTVs, and we propose a formation scenario in which the capture in resonance occurring during migration in a disc with strong eccentricity damping is followed by eccentricity excitation during the dispersal of the disc, assisted by a third planet whose presence has been suggested by radial velocity observations. This scenario accounts for the eccentricities of the two planets and their period ratio, and accurately reproduces the amplitude and period of the TTVs. It allows for a unified view of the formation and evolution history of K2-24, from disc-induced migration to its currently observed properties.

9 pages, 7 figures. Accepted for publication in Astronomy and Astrophysics

References in corpus (14)

• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• 197 Candidates and 104 Validated Planets in K2's First Five Fields
• Mass Estimates of a Giant Planet in a Protoplanetary Disk from the Gap Structures
• Resonant Repulsion of Kepler Planet Pairs
• Planetesimal Interactions Can Explain the Mysterious Period Ratios of Small Near-Resonant Planets
• Accretion of Terrestrial Planets from Oligarchs in a Turbulent Disk
• Tidal dissipation and the formation of Kepler near-resonant planets
• Evolution of eccentricity and orbital inclination of migrating planets in 2:1 mean motion resonance
• Why are there so few hot Jupiters?
• PDS 70: A transition disk sculpted by a single planet
• The origin of the eccentricity of the hot Jupiter in CI Tau
• Trapping of Low-Mass Planets Outside the Truncated Inner Edges of Protoplanetary Discs
• Radial migration of gap-opening planets in protoplanetary disks. II. The case of a planet pair
• The role of disc torques in forming resonant planetary systems

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