Space weathering of small Koronis family members

Cristina A. Thomas, Andrew S. Rivkin, David E. Trilling, Enga Marie-therese Enga, Jennifer A. Grier

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

The space weathering process and its implications for the relationships between S- and Q-type asteroids and ordinary chondrite meteorites is an often debated topic in asteroid science. Q-type asteroids have been shown to display the best spectral match to ordinary chondrites (McFadden, L.A., Gaffey, M.J., McCord, T.B. [1985]. Science 229, 160-163). While the Q-types and ordinary chondrites share some spectral features with S-type asteroids, the S-types have significantly redder spectral slopes than the Q-types in visible and near-infrared wavelengths. This reddening of spectral slope is attributed to the effects of space weathering on the observed surface composition. The analysis by Binzel et al. (Binzel, R.P., Rivkin, A.S., Stuart, J.S., Harris, A.W., Bus, S.J., Burbine, T.H. [2004]. Icarus 170, 259-294) provided a missing link between the Q- and S-type bodies in near-Earth space by showing a reddening of spectral slope in objects from 0.1 to 5. km that corresponded to a transition from Q-type to S-type asteroid spectra, implying that size, and therefore surface age, is related to the relationship between S- and Q-types. The existence of Q-type asteroids in the main-belt was not confirmed until Mothé-Diniz and Nesvorny (Mothé-Diniz, T., Nesvorny, D. [2008]. Astron. Astrophys. 486, L9-L12) found them in young S-type clusters. The young age of these families suggest that the unweathered surface could date to the formation of the family. This leads to the question of whether older S-type main-belt families can contain Q-type objects and display evidence of a transition from Q- to S-type. To answer this question we have carried out a photometric survey of the Koronis family using the Kitt Peak 2.1. m telescope. This provides a unique opportunity to compare the effects of the space weathering process on potentially ordinary chondrite-like bodies within a population of identical initial conditions. We find a trend in spectral slope for objects 1-5. km that shows the transition from Q- to S-type in the main-belt. This data set will prove crucial to our understanding of the space weathering process and its relevant timescales.

Original languageEnglish (US)
Pages (from-to)158-166
Number of pages9
JournalIcarus
Volume212
Issue number1
DOIs
StatePublished - Mar 1 2011

Keywords

  • Asteroids
  • Asteroids, Surfaces
  • Spectrophotometry

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Thomas, C. A., Rivkin, A. S., Trilling, D. E., Marie-therese Enga, E., & Grier, J. A. (2011). Space weathering of small Koronis family members. Icarus, 212(1), 158-166. https://doi.org/10.1016/j.icarus.2010.12.021