Composition-dependent outgassing of comet 67P/Churyumov-Gerasimenko from ROSINA/DFMS

Implications for nucleus heterogeneity?

¹ Department of Space Research, Space Science and Engineering Division, Southwest Research Institute 6220 Culebra Rd., San Antonio, TX 78238, USA
e-mail: aluspaykuti@swri.edu
² Physikalisches Institut, Universität Bern, Sidlerstr. 5, 3012 Bern, Switzerland
³ Center for Space and Habitability (CSH), Universität Bern, Sidlerstr. 5, 3012 Bern, Switzerland
⁴ Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
⁵ Belgian Institute for Space Aeronomy, BIRA-IASB, Ringlaan 3, 1180 Brussels, Belgium
⁶ Center for Plasma Astrophysics, K.U. Leuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium
⁷ LATMOS/IPSL-CNRS-UPMC-UVSQ, 4 avenue de Neptune, 94100 Saint-Maur, France
⁸ Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig, Germany
⁹ Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
¹⁰ Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany

Received: 27 March 2015
Accepted: 9 June 2015

Abstract

Context. Early measurements of Rosetta’s target comet, 67P/Churyumov-Gerasimenko (67P), showed a strongly heterogeneous coma in H₂O, CO, and CO₂.

Aims. The purpose of this work is to further investigate the coma heterogeneity of 67P, and to provide predictions for the near-perihelion outgassing profile based on the proposed explanations.

Methods. Measurements of various minor volatile species by ROSINA/DFMS on board Rosetta are examined. The analysis focuses on the currently poorly illuminated winter (southern) hemisphere of 67P.

Results. Coma heterogeneity is not limited to the major outgassing species. Minor species show better correlation with either H₂O or CO₂. The molecule CH₄ shows a different diurnal pattern from all other analyzed species. Such features have implications for nucleus heterogeneity and thermal processing.

Conclusions. Future analysis of additional volatiles and modeling the heterogeneity are required to better understand the observed coma profile.