Variegation of active regions on comet 67P/Churyumov-Gerasimenko

Since Rosetta spacecraft’s arrival to the comet 67P, the OSIRIS scientific imager (Optical, Spectroscopic, and Infrared Remote Imaging System, Keller et al. 2007) is successfully observing the nucleus with high spatial resolution in the 250-1000 nm range thanks to set of 26 dedicated filters.While 67P has a typical red spectral slope, the active areas tend to display bluer spectra (Sierks et al. 2015, Fornasier et al. 2015). We performed a spectral analysis of the active areas and derived spectral characteristics of them, possibly indicating the presence of material enriched in volatiles.The ‘activity thresholds’ spectral method (Oklay et al, 2015) is used for the identification of the active areas. In most cases, areas detected with this technique have been later on confirmed as active sources (Lara et al. 2015, Lin et al. 2015, Vincent et al. 2015) by direct detection of dust jets. This technique is therefore able to identify currently active areas, but also predicts which regions of the surface are likely to become activated once they receive enough insolation.Acknowledgements: OSIRIS was built by a consortium led by the Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany, in collaboration with CISAS, University of Padova, Italy, the Laboratoire d'Astrophysique de Marseille, France, the Instituto de Astrofi­sica de Andalucia, CSIC, Granada, Spain, the Scientific Support Office of the European Space Agency, Noordwijk, The Netherlands, the Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, the Universidad Politechnica de Madrid, Spain, the Department of Physics and Astronomy of Uppsala University, Sweden, and the Institut für Datentechnik und Kommunikationsnetze der Technischen Universität Braunschweig, Germany. We thank the Rosetta Science Ground Segment at ESAC, the Rosetta Mission Operations Centre at ESOC and the Rosetta Project at ESTEC for their outstanding work enabling the science return of the Rosetta Mission.Keller, et al. 2007, Space Sci. Rev., 128, 433Sierks et al. 2015, Science, 347,1Fornasier et al. 2015, A&A, published onlineLara et al. 2015, A&A, published onlineLin et al. 2015, A&A, published onlineVincent et al. 2015, A&A, submittedOklay et al. 2015, in preparation