Hektor - an exceptional D-type family among Jovian Trojans

Abstract

In this work, we analyze Jovian Trojans in the space of suitable resonant elements and we identify clusters of possible collisional origin by two independent methods: the hierarchical clustering and a so-called "randombox". Compared to our previous work (Brož and Rozehnal 2011), we study a twice larger sample. Apart from Eurybates, Ennomos and $1996\mathrm{RJ}$ families, we have found three more clusters --- namely families around asteroids (20961)~Arkesilaos, (624)~Hektor in the $L_4$ libration zone and (247341)~$2001\mathrm{U}{\mathrm{V}}_{209}$ in $L_5$. The families fulfill our stringent criteria, i.e. a high statistical significance, an albedo homogeneity and a steeper size-frequency distribution than that of background. In order to understand their nature, we simulate their long term collisional evolution with the Boulder code (Morbidelli et al. 2009) and dynamical evolution using a modified SWIFT integrator (Levison and Duncan, 1994). Within the framework of our evolutionary model, we were able to constrain the the age of the Hektor family to be either 1 to 4 Gyr or, less likely, 0.1 to 2.5 Gyr, depending on initial impact geometry. Since (624) Hektor itself seems to be a bilobed--shape body with a satellite (Marchis et al. 2014), i.e. an exceptional object, we address its association with the D--type family and we demonstrate that the moon and family could be created during a single impact event. We simulated the cratering event using a Smoothed Particle Hydrodynamics (SPH, Benz and Asphaug, 1994). This is also the first case of a family associated with a D--type parent body.

accepted to MNRAS

References in corpus (3)

• Standing on the shoulders of giants: Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids
• Constraining the cometary flux through the asteroid belt during the late heavy bombardment
• The Eos family halo

Cited by in corpus (10)

• Origin and evolution of long-period comets
• On the Ages of Resonant, Eroded and Fossil Asteroid Families
• Stability of Jovian Trojans and their collisional families
• Origin and Evolution of Jupiter's Trojan Asteroids
• Implications for the collisional strength of Jupiter Trojans from the Eurybates family
• The young Hobson family: Possible binary parent body and low-velocity dispersal
• Astrocladistics of the Jovian Trojan Swarms
• Rotationally-resolved spectroscopy of Jupiter Trojans (624) Hektor and (911) Agamemnon
• Photometric Confirmation and Characterization of the Ennomos Collisional Family in the Jupiter Trojans
• Ultraviolet Spectroscopy of Lucy Mission Targets with the Hubble Space Telescope