Yarkovsky-driven spreading of the Eureka family of Mars Trojans

•We numerically model orbital evolution of the Eureka cluster of Mars Trojans.•Eureka cluster is a genetic family spread by Yarkovsky effect.•Sub-kilometer Mars Trojans are dominated by the seasonal Yarkovsky effect. Out of nine known stable Mars Trojans, seven appear to be members of an orbital gro...

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Bibliographic Details
Published in:Icarus (New York, N.Y. 1962) N.Y. 1962), 2015-05, Vol.252, p.339-346
Main Authors: Ćuk, Matija, Christou, Apostolos A., Hamilton, Douglas P.
Format: Article
Language:English
Subjects:
Asteroids
Asteroids, dynamics
Celestial mechanics
Clusters
Current distribution
Evolution
Genetics
Gravitation
Mars
Orbitals
Planetary dynamics
Rotational
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Summary:•We numerically model orbital evolution of the Eureka cluster of Mars Trojans.•Eureka cluster is a genetic family spread by Yarkovsky effect.•Sub-kilometer Mars Trojans are dominated by the seasonal Yarkovsky effect. Out of nine known stable Mars Trojans, seven appear to be members of an orbital grouping including the largest Trojan, Eureka. In order to test if this could be a genetic family, we simulated the long term evolution of a tight orbital cluster centered on Eureka. We explored two cases: cluster dispersal through planetary gravity alone over 1Gyr, and a 1Gyr evolution due to both gravity and the Yarkovsky effect. We find that the dispersal of the cluster in eccentricity is primarily due to dynamical chaos, while the inclinations and libration amplitudes are primarily changed by the Yarkovsky effect. Current distribution of the cluster members orbits is indicative of an initially tight orbital grouping that was affected by a negative acceleration (i.e. one against the orbital motion) consistent with the thermal Yarkovsky effect. We conclude that the cluster is a genetic family formed either in a collision or through multiple rotational fissions. The cluster’s age is on the order of 1Gyr, and its long-term orbital evolution is likely dominated by the seasonal, rather than diurnal, Yarkovsky effect. If confirmed, Gyr-scale dominance of the seasonal Yarkovsky effect may indicate suppression of the diurnal Yarkovsky drift by the related YORP effect. Further study of Mars Trojans is essential for understanding the long-term orbital and rotational dynamics of small bodies in the absence of frequent collisions.
ISSN:0019-1035
1090-2643
DOI:10.1016/j.icarus.2015.02.009