arXiv subjects

V. Frohlich

Publications and source records attributed to V. Frohlich.

3 recordsLinked to original sources

arXiv2026

Rings Around Non-Spherical Worlds: Sub-mm Dust Retention Around Triaxial Small Bodies in the Solar System

We investigated the millennial-scale evolution of narrow innermost rings composed of pebble-sized to sub-millimeter particles around the four known ring-bearing small bodies Chiron, Chariklo, Quaoar, and Haumea. Using a GPU-accelerated 8th-order Hermite integrator, we modeled the combined effects of solar radiation pressure (RP), shadowing of the rings by the host body, heliocentric motion, and the non-axisymmetric gravitational field of the rotating triaxial central body. The calculations compare spherical and triaxial-body models, as well as coplanar and inclined ring configurations. In spherical models, solar RP excites particle eccentricities, leading to accretion onto the central body above a critical RP parameter. This effect is strongest for the lower-mass systems, Chiron and Chariklo, where particles with relatively modest radiation forcing are rapidly removed. In contrast, when the triaxial shape of the host body is included, rapid apsidal precession suppresses RP-driven eccentricity growth and prevents material loss from the ring over the simulated interval. The triaxial models also suppress the previously identified Sun-facing reorientation of highly inclined rings and instead produce moderate vertical broadening. Strongly confined rings persist for RP parameters corresponding to particle sizes larger than about 7-40 micrometers, depending on composition. Their characteristic radial widths are about 10 km for Chiron and Chariklo and about 40-70 km for Quaoar and Haumea. The vertical thicknesses of the rings are estimated to be on the order of 1 km for Chiron and Chariklo, and only several hundred meters for Quaoar and Haumea. Our results suggest that narrow rings around triaxial small bodies in the Solar System can plausibly retain sub-millimeter particles over dynamically relevant timescales shorter than Poynting-Robertson drag.

astro-ph.EP↗

arXiv2025

Celestial sunflowers -- Survival of rings around small planetary bodies under solar radiation pressure

Context: Rings around giant planets are a common feature of the solar system. Even though solar radiation pressure is known to destabilize rings by exciting the orbital eccentricity of its particles, the Centaur Chariklo (and possibly Chiron), the dwarf planet Haumea, and trans-Neptunian object Quaoar also host rings of solid material. Aims: We explore the dynamical evolution of rings around spherical Chariklo and Haumea analogs, assuming different particle sizes and tilt angles with respect to the planetary orbital plane of the ring. Methods: The ring dynamics were studied using a GPU-based N-body integrator with an 8th-order Hermite scheme for several thousand years, corresponding to 10 solar orbits. The simulations took into account the gravitational effects of the planet and the Sun, radiation pressure, and the shadow cast by the planet. Results: Two families of rings have been identified depending on the ring tilt angle. Slightly tilted rings (<=40 deg) are unstable under a critical particle size. Highly tilted rings (>=50 deg), however, show instability only for a range of particle sizes that spans 1-10 times the critical size. The planetary shadow reduces the critical size by a factor of five and extends the instability region to 0.1-10 times this newly identified critical size. Conclusions: The stabilization of highly inclined rings occurs because the plane of the ring is forced to be perpendicular to the Solar radiation. As a result, the plane of the ring rotates as the planetary bodies revolves: always facing the sun, like a celestial sunflower. Rings which are closely aligned to the orbital plane of the host planet, such as Haumea and Quaoar, presumably consist of particles with a size at least 1-4 um. However, particles in the rings which are highly tilted, like that around Chariklo and Chiron, should consist of particles <=2.5-15 um or >=60-300 um.

astro-ph.EP↗

arXiv2023

Mitigating potentially hazardous asteroid impacts revisited

Context: Potentially hazardous asteroids (PHA) in Earth-crossing orbits pose a constant threat to life on Earth. Several mitigation methods have been proposed, and the most feasible technique appears to be the disintegration of the impactor and the generation of a fragment cloud by explosive penetrators at interception. However, mitigation analyses tend to neglect the effect of orbital dynamics on the trajectory of fragments. Aims: We aim to study the effect of orbital dynamics of the impactor's cloud on the number of fragments that hit the Earth, assuming different interception dates. We investigate the effect of self-gravitational cohesion and the axial rotation of the impactor. Methods: We computed the orbits of 10^5 fragments with a high-precision direct N-body integrator of the eighth order, running on GPUs. We considered orbital perturbations from all large bodies in the Solar System and the self-gravity of the cloud fragments. Results: Using a series of numerical experiments, we show that orbital shear causes the fragment cloud to adopt the shape of a triaxial ellipsoid. The shape and alignment of the triaxial ellipsoid are strongly modulated by the cloud's orbital trajectory and, hence, the impact cross-section of the cloud with respect to the Earth. Therefore, the number of fragments hitting the Earth is strongly influenced by the orbit of the impactor and the time of interception. A minimum number of impacts occur for a well-defined orientation of the impactor rotational axis, depending on the date of interception. Conclusions: To minimise the lethal consequences of an PHA's impact, a well-constrained interception timing is necessary. A too-early interception may not be ideal for PHAs in the Apollo or Aten groups. Thus, we find that the best time to intercept PHA is when it is at the pericentre of its orbit.

astro-ph.EP↗