37th DPS Meeting, 4-9 September 2005
Session 15 Asteroid Physical Studies
Poster, Monday, September 5, 2005, 6:00-7:15pm, Music Recital Room

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[15.27] Spectroscopic characterization of the Karin family

P. Vernazza, M. Fulchignoni, M. Birlan (Observatoire de Paris), E. Dotto (INAF-OAR, Roma), A. Rossi (ISTI-CNR, Pisa), S. Fornasier, F. Marzari (Dept di Fisica & Astronomia di Padova), D. Nesvorny (SwRI, Boulder)

The Karin asteroidal family was firstly identified by Nesvorny et al. (2002, Nature 417) who numerically integrated the orbits of 39 known members. More recently Nesvorny and Bottke (2004) analyzed a wider sample of objects and, taking into account also the Yarkovsky effect, identified the common origin of 90 family members at 5.75±0.05 Myr in the past. This is an exceptionally young age for an asteroid family. In fact, other known families are thought to be much older, 100 Myr to Gyrs old. We carried out visible and near-infrared spectroscopy of several members of the Karin family. We observed 5 member of the Karin family on November 2003 using the IRTF telescope. These data confirm that 832 Karin is an S-type asteroid (as indicated by Binzel, private communication), characterized by strong absorption features of olivine and pyroxene at about 1 and 2 \mum. Visible spectra for 20 objects were later obtained in December, 2004 with EMMI/NTT (ESO, La Silla) and with MOS/CFHT (Mauna Kea, Hawaii). Fifteen of these objects (832 Karin among them), have S-type spectra with the maximum of each spectra located at a very similar wavelength. This result sustain the hypothesis of a common origin. Five other spectra obtained seem rather primitive (B,C types). We analysed the spectra of the Karin cluster in the context of the Koronis family. This analysis reveals that the spectra are less red than those of the Koronis members. Moreover, we can interpret them as less mature surfaces. Finally, we made an interpretation of the surface composition of 832 Karin, using the Shkuratov scattering model.

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