Exomoons in Systems with a Strong Perturber: Applications to α Cen AB
- Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)
- Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)
- National Radio Astronomy Observatory, Socorro, New Mexico (United States)
The presence of a stellar companion can place constraints on occurrence and orbital evolution of satellites orbiting exoplanets, i.e., exomoons. In this work we revise earlier orbital stability limits for retrograde orbits in the case of a three-body system consisting of a star, planet, and satellite. The revised limit reads a{sub sat}{sup crit}≈0.668(1-1.236e{sub p}) for e {sub p} ≤ 0.8 in units of the Hill Radius and represents the lower critical orbit as a function of the planetary eccentricity e {sub p}. A similar formula is determined for exomoons hosted by planets in binary star systems, where e {sub p} is replaced with the components of free and forced eccentricity from secular orbit evolution theory. By exploring the dynamics of putative exomoons in α Centauri AB we find that the outer stability limit can be much less than half the Hill Radius due to oscillations in the planetary orbital eccentricity caused by the gravitational interaction with the binary star. We show, furthermore, how the resulting truncation of the outer stability limit can affect the outward tidal migration and potential observability of exomoons through transit-timing variations (TTVs). Typical TTV (rms) amplitudes induced by exomoons in binary systems are ≲10 minutes and appear more likely for planets orbiting the less massive stellar component.
- OSTI ID:
- 23159306
- Journal Information:
- The Astronomical Journal (Online), Vol. 162, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
Similar Records
On the Existence of Regular and Irregular Outer Moons Orbiting the Pluto–Charon System
MAGNETIC SHIELDING OF EXOMOONS BEYOND THE CIRCUMPLANETARY HABITABLE EDGE