Searching for primitive, dark, spectrally red asteroid families in the main belt with Gaia

Ullas Bhat; Chrysa Avdellidou; Marco Delbo; Thomas Dyer

doi:10.1093/mnras/staf2067

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arXiv · 2511.16495

Searching for primitive, dark, spectrally red asteroid families in the main belt with Gaia

Ullas Bhat·Chrysa Avdellidou·Marco Delbo·Thomas Dyer

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Abstract

Dark asteroids with featureless neutral to red spectra are of particular interest due to their ability to potentially harbour primitive, hydrated, and possibly organic-rich material. These asteroids belong to the spectroscopic C-complex, to the X-types with low geometric visible albedo values as well as to the T- and D-type end members of the Bus-DeMeo spectroscopic taxonomy. Here we used Gaia Data Release 3 visible reflectance spectra to study the average spectral profiles of the C- and X-complex asteroid families in the central and outer main belt (orbital semi-major axis between 2.5 - 3.7~au). We found that eight of these families, namely 96 Aegle, 627 Charis, 1484 Postrema and 5438 Lorre, previously classified as C-complex families, and 322 Phaeo, 1303 Luthera, 5567 Durisen and 53546 2000BY6 previously classified as X-complex families, have redder slopes than implied by their previous classification and could be better classified as T-/D-type families. Some of these families may also feed the near-Earth asteroid population, being responsible for the observed T-/D-type excess. However, the analysis of their principal components of Gaia Data Release 3 spectra suggest that further near-infrared observations are needed in order to verify this identification.

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Ullas Bhat, Chrysa Avdellidou, Marco Delbo, Thomas Dyer. 2025-11-20. Searching for primitive, dark, spectrally red asteroid families in the main belt with Gaia. https://doi.org/10.1093/mnras%2Fstaf2067

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