Spectrophotometry of the Khonsu region on the comet 67P/Churyumov-Gerasimenko using OSIRIS instrument images

J. D. P. Deshapriya (1) , M. A. Barucci (1) , S. Fornasier (1) , C. Feller (1) , P. H. Hasselmann (1) , H. Sierks (2) , M. R. El-Maarry (3) , M. Pajola (4) , C. Barbieri (5) , Philippe L. Lamy (6) , R. Rodrigo (7, 8) , Detlef Koschny (9) , H. Rickman (10, 11) , Jessica Agarwal (2) , Michael F. A'Hearn (12) , Jean-Loup Bertaux (13) , I. Bertini (5) , S. Boudreault (2) , Gabriele Cremonese (14) , V. Da deppo (15) , B. J. R. Davidsson (16) , S. Debei (17) , J. Deller (2) , M. De cecco (18) , M. Fulle (19) , A. Gicquel (2) , Olivier Groussin (6) , P. J. Gutierrez (20) , C. Güttler (2) , M. Hofmann (2) , S. F. Hviid (21) , W. Ip (22) , L. Jorda (6) , H.U. Keller (23) , J. Knollenberg (21) , R. Kramm (2) , Ekkehard Kührt (21) , M. Küppers (24) , L. Lara (20) , M. Lazzarin (5) , J.J. Lopez Moreno (20) , F. Marzari (5) , S. Mottola (21) , G. Naletto (25, 26, 15) , N. Oklay (2) , D. Perna (1) , A. Pommerol (3) , N. Thomas (3) , C. Tubiana (2) , Jean-Baptiste Vincent (2)

1 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
2 MPS - Max-Planck-Institut für Sonnensystemforschung
3 Physikalisches Institut [Bern]
4 ARC - NASA Ames Research Center
5 Dipartimento di Fisica e Astronomia "Galileo Galilei"
6 LAM - Laboratoire d'Astrophysique de Marseille
7 CAB - Centro de Astrobiologia [Madrid]
8 ISSI - International Space Science Institute [Bern]
9 ESTEC - European Space Research and Technology Centre
10 CBK - Space Research Centre of Polish Academy of Sciences
11 Department of Physics and Astronomy [Uppsala]
12 Department of Astronomy [College Park]
13 PLANETO - LATMOS
14 OAPD - INAF - Osservatorio Astronomico di Padova
15 IFN - CNR Institute for Photonics and Nanotechnologies
16 JPL - Jet Propulsion Laboratory
17 Department of Industrial Engineering [Padova]
18 UNITN - Università degli Studi di Trento
19 OAT - INAF - Osservatorio Astronomico di Trieste
20 IAA - Instituto de Astrofísica de Andalucía
21 DLR Institut für Planetenforschung
22 Institute of Space Science [Taiwan]
23 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
24 Operations Department (ESAC)
25 DEI - Department of Information Engineering [Padova]
26 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”

Our work focuses on the spectrophotometric analysis of selected terrain and bright patches in the Khonsu region on the comet 67P/Churyumov-Gerasimenko. Despite the variety of geological features, their spectrophotometric properties appear to indicate a similar composition. It is noticeable that the smooth areas in Khonsu possess similar spectrophotometric behaviour to some other regions of the comet. We observed bright patches on Khonsu with an estimation of > 40% of normal albedo and suggest that they are associated to H₂O ice. One of the studied bright patches has been observed to exist on the surface for more than 5 months without a major decay of its size, implying the existence of potential subsurface icy layers. Its location may be correlated with a cometary outburst during the perihelion passage of the comet in August 2015, and we interpret it to have triggered the surface modifications necessary to unearth the stratified icy layers beneath the surface. A boulder analysis on Khonsu leads to a power-law index of -3.1 +0.2/-0.3 suggesting a boulder formation, shaped by varying geological processes for different morphological units.

Domains: Earth and Planetary Astrophysics [astro-ph.EP]; Sciences of the Universe [physics]; Astrophysics [astro-ph]

J. D. P. Deshapriya, M. A. Barucci, S. Fornasier, C. Feller, P. H. Hasselmann, et al.. Spectrophotometry of the Khonsu region on the comet 67P/Churyumov-Gerasimenko using OSIRIS instrument images. Monthly Notices of the Royal Astronomical Society, 2016, 462 (Suppl. 1), pp.S274-S286. ⟨10.1093/mnras/stw2530⟩. ⟨insu-01376715⟩