A visible and near-IR spectral search for NEOs originating from the Euphrosyne Main-belt asteroid family.
Abstract
Members of asteroid families are given a velocity kick following the partial or catastrophic disruption of a parent body that causes them to spread out in orbital-element-space. Subsequent gravitational perturbations and non-gravitational forces such as the Yarkovsky effect can result in family members entering a mean-motion or secular resonance, and being transported into the NEO population (defined as objects with perihelia q< 1:3 AU, see Bottke et al. 2002). The 800 Myr old Euphrosyne family is the only known asteroid family bisected by the v6 secular resonance. Recent work by Masiero et al. (2015) traces the dynamical evolution of Euphrosyne family members over the family's lifetime, showing that members near the v6 secular resonance will evolve to populate a specific sub-region of NEO orbital element space. In this work, we will present observations of both main belt members and near-Earth candidates made using visible and near-IR spectrometers on the Palomar 5-m and NASA IRTF 3-m telescopes, respectively. While the majority of the NEO candidates appear consistent with other spectral types, we have at least one NEO candidate that appears to originate from the carbonaceous-type Euphrosyne family. Relative to the main-belt family spectra, this NEO does not show any evidence of spectral variations between the near-Earth and main-belt populations. Near-Earth objects should experience increased solar heating and ion bombardment relative to objects in the main-belt, however processes resulting from close planetary encounters can also refresh the regolith of NEOs (Binzel et al. 2010). Either process would result in a highly mature regolith or fresh surfaces for Euphrosyne-type NEOs. Assuming the Euphrosyne-type NEO does indeed originate from the Euphrosyne family, the lack of spectral variation indicates several possibilities. One is that this NEO was recently injected into its current orbit, and thus should have similar features as its main-belt family. Another possibility is that if this NEO was not recently injected, the lack of spectral variations may indicate that space weathering processes do not manifest in the spectra of these carbonaceous main-belt and near-Earth objects.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #50
- Pub Date:
- October 2018
- Bibcode:
- 2018DPS....5010506K