Exchange of ejecta between Telesto and Calypso: Tadpoles, horseshoes, and passing orbits - Astrophysics > Earth and Planetary AstrophysicsReportar como inadecuado




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Abstract: We have numerically integrated the orbits of ejecta from Telesto and Calypso,the two small Trojan companions of Saturn-s major satellite Tethys. Ejecta werelaunched with speeds comparable to or exceeding their parent-s escape velocity,consistent with impacts into regolith surfaces. We find that the fates ofejecta fall into several distinct categories, depending on both the speed anddirection of launch.The slowest ejecta follow sub-orbital trajectories and re-impact their sourcemoon in less than one day. Slightly faster debris barely escape their parent-sHill sphere and are confined to tadpole orbits, librating about Tethys-triangular Lagrange points L4 leading, near Telesto or L5 trailing, nearCalypso with nearly the same orbital semi-major axis as Tethys, Telesto, andCalypso. These ejecta too eventually re-impact their source moon, but with amedian lifetime of a few dozen years. Those which re-impact within the firstten years or so have lifetimes near integer multiples of 348.6 days half thetadpole period.Still faster debris with azimuthal velocity components >~ 10 m-s enterhorseshoe orbits which enclose both L4 and L5 as well as L3, but which avoidTethys and its Hill sphere. These ejecta impact either Telesto or Calypso atcomparable rates, with median lifetimes of several thousand years. However,they cannot reach Tethys itself; only the fastest ejecta, with azimuthalvelocities >~ 40 m-s, achieve -passing orbits- which are able to encounterTethys. Tethys accretes most of these ejecta within several years, but some 1 %of them are scattered either inward to hit Enceladus or outward to strikeDione, over timescales on the order of a few hundred years.



Autor: Anthony R. Dobrovolskis, Jose' Luis Alvarellos, Kevin J. Zahnle, Jack J. Lissauer

Fuente: https://arxiv.org/







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