Emission of decimetre-sized debris from comet 67P

Jupiter-family comet 67P/Churyumov-Gerasimenko was orbited by ESA’s Rosetta spacecraft for more than two years during its 2014-2016 perihelion passage. Rosetta’s scientific camera system OSIRIS repeatedly caught evidence of decimetre-sized chunks of debris leaving the comet’s near-surface environment and travelling the inner coma. The chunks are typically visible as individual point sources, either as bright streaks in single long-exposure images, or as dotted lines in stacks of high-cadence image sequences. The combinations of measured brightness and angular speed allows us to constrain their sizes, speeds, and source regions, if plausible assumptions about their distances and albedos are made (Agarwal et al, 2016).

Pfeifer et al. (2022, 2024) and Lemos et al. (2023, 2024) have developed algorithms to automatically detect and track chunks across images sequences, finding indications that their emission is concentrated in specific regions on the comet and that they leave the surface with an initial speed of about 1 m/s that is not explained by standard coma gas drag formalism.

While these earlier publications each concentrated on a few sets of images, we now aim to analyze the OSIRIS data set more comprehensively. In this presentation we review the available data and discuss their potential for studying the evolution of the chunk emission with time, as the comet approached perihelion and subsequently receded from the sun.

 

References:

Agarwal, J., A’Hearn, M. F., Vincent, J.-B., et al. (2016) MNRAS, 462, S78

Lemos, P., Agarwal, J., & Schröter, M. (2023) MNRAS, 519, 5775

Lemos, P., Agarwal, J., Marschall, R., Pfeifer, M. (2024), A&A 687, A289

Pfeifer, M., Agarwal, J., & Schröter, M. (2022) A&A, 659, A171

Pfeifer, M., Agarwal, J., Marschall, R., Grieger, B., & Lemos, P. (2024) A&A, 685, A136