Orbital Stability of Exomoons and Submoons with Applications to Kepler 1625b-I

Abstract

An intriguing question in the context of dynamics arises: Could a moon possess a moon itself? Such a configuration does not exist in the Solar System, although this may be possible in theory. Kollmeier et al. (2019) determined the critical size of a satellite necessary to host a long-lived sub-satellite, or submoon. However, the orbital constraints for these submoons to exist are still undetermined. Domingos et al. (2006) indicated that moons are stable out to a fraction of the host planet Hill radius $R_{H,p}$, which in turn depends on the eccentricity of its host's orbit. Motivated by this, we simulate a system of exomoons and submoons for $10^5$ planetary orbits, while considering many initial orbital phases to obtain the critical semimajor axis in terms of $R_{H,p}$ or the hosts satellite's Hill radius $R_{H,sat}$, respectively. We find that, assuming circular coplanar orbits, the stability limit for exomoons is 0.40 $R_{H,p}$ and for a submoon is 0.33 $R_{H,sat}$. Additionally, we discuss the observational feasibility of detecting these sub-satellites through photometric, radial velocity, or direct imaging observations using the Neptunes-sized exomoon candidates Kepler 1625b-I (Teachey et al. 2018) and identify how stability can shape the identification of future candidates.

Accepted to AJ. 15 pages, 5 figures, 2 tables

References in corpus (9)

• Transit timing effects due to an exomoon
• Irregular Satellites of the Planets: Products of Capture in the Early Solar System
• Detecting companions to extrasolar planets using mutual events
• No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System
• An alternative interpretation of the exomoon candidate signal in the combined Kepler and Hubble data of Kepler-1625
• Habitability of Earth-type Planets and Moons in the Kepler-16 System
• Microlensing Detections of Moons of Exoplanets
• Orbital Stability of Circumstellar Planets in Binary Systems
• Transits of Inclined Exomoons - Hide and Seek and an Application to Kepler-1625

Cited by in corpus (12)

• Application of Orbital Stability and Tidal Migration Constraints for Exomoon Candidates
• Cronomoons: origin, dynamics, and light-curve features of ringed exomoons
• Stability and detectability of exomoons orbiting HIP 41378 f, a temperate Jovian planet with an anomalously low apparent density
• The Exomoon Corridor for Multiple Moon Systems
• Exomoons in Systems with a Strong Perturber: Applications to $\alpha$ Cen AB
• On the Stability of Additional Moons Orbiting Kepler-1625 b
• Updated Studies on Exomoons in the HD 23079 System
• On the motion of satellite around the natural moons of planets using the concept of ER3BP with variable eccentricity
• Exploring Exoplanet Dynamics with JWST: Tides, Rotation, Rings, and Moons
• Transit Duration and Timing Variations from Binary Planets
• The Dynamics of Co-orbital Giant Exomoons -- Applications for the Kepler-1625 b and Kepler-1708 b Satellite Systems
• Moon-packing around an Earth-mass Planet