Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko

Abstract

The Rosetta space probe accompanied comet 67P/Churyumov-Gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. This work focuses identifying the source regions of faint jets and outbursts and on studying the spectrophotometric properties of some outbursts. We use observations acquired with the OSIRIS/NAC camera during July-October 2015, that is, close to perihelion. More than 200 jets of different intensities were identified directly on the nucleus. Some of the more intense outbursts appear spectrally bluer than the comet dark terrain in the vivible-to-near-infrared region. We attribute this spectral behavior to icy grains mixed with the ejected dust. Some of the jets have an extremely short lifetime. They appear on the cometary surface during the color sequence observations, and vanish in less than some few minutes after reaching their peak. We also report a resolved dust plume observed in May 2016 at a resolution of 55 cm/pixel, which allowed us to estimate an optical depth of $\sim$0.65 and an ejected mass of $\sim$ 2200 kg. We present the results on the location, duration, and colors of active sources on the nucleus of 67P from the medium-resolution (i.e., 6-10 m/pixel) images acquired close to perihelion passage. The observed jets are mainly located close to boundaries between different morphological regions. Jets depart not only from cliffs, but also from smooth and dust-covered areas, from fractures, pits, or cavities that cast shadows and favor the recondensation of volatiles. This study shows that faint jets or outbursts continuously contribute to the cometary activity close to perihelion passage, and that these events are triggered by illumination conditions. Faint jets or outbursts are not associated with a particular terrain type or morphology.

arXiv commentAccepted for publication on Astronomy and Astrophysics on 27 August 2018. 27 pages, 18 figures, 2 tables

References in corpus (13)

• scikit-image: Image processing in Python
• Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft
• Summer fireworks on comet 67P
• Are fractured cliffs the source of cometary dust jets ? Insights from OSIRIS/Rosetta at 67P
• Water Ice and Dust in the Innermost Coma of Comet 103P/Hartley 2
• Evolution of CO${}_2$, CH${}_4$, and OCS abundances relative to H${}_2$O in the coma of comet 67P around perihelion from Rosetta/VIRTIS-H observations
• Comet 67P outbursts and quiescent coma at 1.3 AU from the Sun: dust properties from Rosetta/VIRTIS-H observations
• Evidence of sub-surface energy storage in comet 67P from the outburst of 2016 July 3
• The highly active Anhur-Bes regions in the 67P/Churyumov - Gerasimenko comet: results from OSIRIS/ROSETTA observations
• Observations and analysis of a curved jet in the coma of comet 67P/Churyumov-Gerasimenko
• Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations
• The perihelion activity of comet 67P/Churyumov-Gerasimenko as seen by robotic telescopes
• ROSETTA/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry

Cited by in corpus (12)

• Surface evolution of the Anhur region on comet 67P from high-resolution OSIRIS images
• Volatile exposures on the 67P/Churyumov-Gerasimenko nucleus
• The ice composition close to the surface of comet 67P/Churyumov-Gerasimenko
• Analysis of Hybrid Gas-Dust Outbursts Observed at 67P/Churyumov-Gerasimenko
• ROSETTA/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry
• Ejection and Dynamics of Aggregates in the Coma of Comet 67P/Churyumov-Gerasimenko
• Dynamics and potential origins of decimeter-sized particles around comet 67P/Churyumov-Gerasimenko
• A comprehensive study of comet 67P/Churyumov-Gerasimenko in the 2021/2022 apparition. II. Colorimetry, polarimetry, modeling
• An impact-free mechanism to deliver water to terrestrial planets and exoplanets
• A comprehensive study of comet 67P/Churyumov-Gerasimenko in the 2021/2022 apparition. I. Photometry, spectroscopy, morphology
• Detection and characterisation of icy cavities on the nucleus of comet 67P/Churyumov-Gerasimenko
• Small lobe of comet 67P: Characterization of the Wosret region with ROSETTA-OSIRIS