Compositional study of asteroids in the Erigone collisional family using visible spectroscopy at the 10.4 m GTC

¹ Instituto de Astrofísica de Canarias (IAC), C/vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
e-mail: damog@iac.es
² Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife, Spain
³ Observatório Nacional, Coordenação de Astronomia e Astrofísica, 20921-400 Rio de Janeiro, Brazil
⁴ GTC Project Office, 38205 La Laguna, Tenerife, Spain
⁵ Physics Department, University of Central Florida, PO Box 162385, Orlando, FL 32816-2385, USA
⁶ Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, 37996 TN, USA
⁷ Laboratoire Lagrange, OCA, Boulevard de l’Observatoire, BP 4229 06304 Nice Cedex 04, France

Received: 25 September 2015
Accepted: 10 December 2015

Abstract

Two primitive near-Earth asteroids, (101955) Bennu and (162173) Ryugu, will be visited by a spacecraft with the aim of returning samples back to Earth. Since these objects are believed to originate in the inner main belt primitive collisional families (Erigone, Polana, Clarissa, and Sulamitis) or in the background of asteroids outside these families, the characterization of these primitive populations will enhance the scientific return of the missions. The main goal of this work is to shed light on the composition of the Erigone collisional family by means of visible spectroscopy. Asteroid (163) Erigone has been classified as a primitive object, and we expect the members of this family to be consistent with the spectral type of the parent body. We have obtained visible spectra (0.5–0.9 μm) for 101 members of the Erigone family, using the OSIRIS instrument at the 10.4 m Gran Telescopio Canarias. We found that 87% of the objects have typically primitive visible spectra consistent with that of (163) Erigone. In addition, we found that a significant fraction of these objects (~50%) present evidence of aqueous alteration.