Speakers
Description
Small near-Earth asteroids (diameter ≲150 m) represent the most numerous yet least characterised segment of potentially hazardous objects in our Solar System (Binzel et al., 2004). Their rapid fading after discovery limits follow-up opportunities, leaving gaps in our understanding of their compositional distribution. Here we present results from an ongoing robotic follow-up programme using the South African Astronomical Observatory's Lesedi telescope (Ngwane et al., 2025), which employs automated scripts to identify NEA discoveries reported to the Minor Planet Center and execute multi-filter photometry within hours of detection. Using green, red, and infrared photometry, we applied a trained machine learning classifier to derive possible taxonomic classifications for 59 small NEAs spanning absolute magnitudes 22 ≤ H < 29 (corresponding to approximate diameters between ~250 m and ~5 m, assuming albedos of 0.05–0.30). We find a roughly 1:1 ratio between stony (S+Q+V) and carbonaceous/metallic (C+X) types, consistent with studies of larger NEAs (Mommert et al., 2016; Erasmus et al., 2017; Janse van Rensburg, 2021). However, we identify a notable overabundance of X-type asteroids, comprising nearly 30% of our sample, exceeding fractions reported for larger objects. Similar trends have been noted in other small-NEA studies (e.g. Devogèle et al., 2019; Hromakina et al., 2021; Moskovitz et al., 2025). The Bus-DeMeo X-complex is spectrally degenerate, encompassing high-albedo E-types, moderate-albedo metallic M-types, and low-albedo primitive P-types, which are difficult to distinguish using standard photometry. This distinction is critical for planetary defence, as impact properties vary significantly between these classes. We discuss the implications of the X-type excess and the potential of polarimetric characterisation for refining compositional constraints of newly discovered small NEAs.
| Apply for student award at which level: | PhD |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |