Achondrites in meteor data: Spectra, dynamics, and physical properties of candidate aubrite and eucrite impactors

Meteor spectroscopy presents new opportunities for investigating the diversity of small Solar System bodies and capturing the real distribution of present material types. In this work, we analyzed a sample of 180 higher-resolution meteor spectra from the All-sky Meteor Orbit System (AMOS) network to search for meteoroids with atypical compositions. In addition to several iron bodies, we have identified the first two achondritic meteoroids in our database, both likely meteorite-dropping impactors. We analyzed the two cases in detail using their spectral, dynamical, and physical properties, and compared them with a reference ordinary chondrite meteoroid observed under similar conditions. The spectral analysis revealed atypical features in the two achondrites - strong Mg and Si and low Fe in one case, and strong Ca, Al, and Ti and low Mg in the other. The measured relative elemental abundances imply an aubrite- and a eucrite-like composition. The aubrite-like meteoroid showed an unexpected enhancement in Ca, Mn, and Ti with short-lived intensity spikes not seen in the eucrite-like case, which we interpret as the rapid release of localized inclusions rather than a bulk enrichment. This indicates that transient spectral features can reveal internal heterogeneity in achondritic meteoroids beyond their average composition. The classification of both meteoroids was found to be consistent with the determined dynamical and physical properties. The eucrite meteoroid originated from an orbit affected by the ν6 resonance in the inner main belt, a common delivery mechanism of HowarditeEucrite-Diogenite meteorites, and exhibited ablation behavior corresponding to a compact material with low erosion and an estimated bulk density of ≈3.16 ± 0.10 g cm−3. The aubrite meteoroid originated from a short-period, low-eccentricity orbit similar to some known E-type near-Earth asteroids. Both events also exhibited atypical light curve behavior, but our results indicate that the robust identification of achondritic meteoroids in meteor surveys generally requires emission spectra. This work presents one of the first detailed studies of achondritic meteoroids from meteor observations and aims to provide reference properties of atypical meteors for more efficient identifications of achondrites in future surveys.