Near-infrared spectroscopy of the Klio primitive inner-belt asteroid family

1Anicia Arredondo,2,3Vania Lorenzi,4Noemi Pinilla-Alonso,1Humberto Campins,1Andrew Malfavon,3,5Juliade León,5,6DavidMorat
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2019.113427]
1Physics Department, University of Central Florida, P.O. Box 162385, Orlando, FL 32816, USA
2Fundación Galileo Galilei – INAF, La Palma (TF), Spain
3Instituto de Astrofísica de Canarias, Tenerife, Spain
4Florida Space Institute, University of Central Florida, Orlando, FL 32816, USA
5Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
6Observatório Nacional, Coordenação de Astronomia e Astrofísica, 20921-400 Rio de Janeiro, Brazil
Copyright Elsevier

The PRIMitive Asteroid Spectroscopic Survey (PRIMASS) aims to characterize primitive asteroids throughout the asteroid belt in the visible and near-infrared (NIR). There are eight primitive families in the inner main belt: Polana-Eulalia, Erigone, Sulamitis, Clarissa, Chaldaea, Klio, Svea and Chimaera. PRIMASS has already characterized all 8 families in the visible, and the Polana-Eulalia complex in the NIR. Results of our previous work show that low inclination inner belt family asteroids fall into at least two distinct compositional groups: Polana-like (anhydrous and spectrally homogeneous) or Erigone-like (hydrated and spectrally diverse). In the visible, the Klio family is spectrally diverse and 23% of the objects show evidence of hydration, but it is not Erigone-like.

We observed 21 objects in the Kilo family using the NASA InfraRed Telescope Facility (IRTF) and the Telescopio Nazionale Galileo (TNG) between January 2017 and March 2019. Our survey shows that the Klio family is spectrally homogeneous in the NIR, i.e., the heterogeneity seen in the visible does not extend to the NIR. The Klio family NIR spectra have mostly convex shapes and have red slopes (average slope 1.052 ± 0.425%/1000 Å normalized at 1.0 μm). The average spectra of both families we have studied in the NIR (Polana-Eulalia and Klio) differ slightly in spectral shape and slope, consistent with space weathering effects, but not conclusively so. Based on our NIR spectral comparisons, the Klio family cannot be ruled out as a possible source for two near-Earth asteroids: (101955) Bennu and (162173) Ryugu.

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