TY  - JOUR
A1  - Marschall, Raphael
A1  - Skorov, Yuri
A1  - Zakharov, Vladimir
A1  - Rezac, Ladislav
A1  - Gerig, Selina-Barbara
A1  - Christou, Chariton
A1  - Dadzie, S. Kokou
A1  - Migliorini, Alessandra
A1  - Rinaldi, Giovanna
A1  - Agarwal, Jessica
A1  - Vincent, Jean-Baptiste
A1  - Kappel, David
T1  - Cometary comae-surface links the physics of gas and dust from the surface to a spacecraft
JF  - Space science reviews
N2  - A comet is a highly dynamic object, undergoing a permanent state of change. These changes have to be carefully classified and considered according to their intrinsic temporal and spatial scales. The Rosetta mission has, through its contiguous in-situ and remote sensing coverage of comet 67P/Churyumov-Gerasimenko (hereafter 67P) over the time span of August 2014 to September 2016, monitored the emergence, culmination, and winding down of the gas and dust comae. This provided an unprecedented data set and has spurred a large effort to connect in-situ and remote sensing measurements to the surface. In this review, we address our current understanding of cometary activity and the challenges involved when linking comae data to the surface. We give the current state of research by describing what we know about the physical processes involved from the surface to a few tens of kilometres above it with respect to the gas and dust emission from cometary nuclei. Further, we describe how complex multidimensional cometary gas and dust models have developed from the Halley encounter of 1986 to today. This includes the study of inhomogeneous outgassing and determination of the gas and dust production rates. Additionally, the different approaches used and results obtained to link coma data to the surface will be discussed. We discuss forward and inversion models and we describe the limitations of the respective approaches. The current literature suggests that there does not seem to be a single uniform process behind cometary activity. Rather, activity seems to be the consequence of a variety of erosion processes, including the sublimation of both water ice and more volatile material, but possibly also more exotic processes such as fracture and cliff erosion under thermal and mechanical stress, sub-surface heat storage, and a complex interplay of these processes. Seasons and the nucleus shape are key factors for the distribution and temporal evolution of activity and imply that the heliocentric evolution of activity can be highly individual for every comet, and generalisations can be misleading.
KW  - comets
KW  - coma
KW  - gas
KW  - dust
KW  - dynamics
KW  - modelling
KW  - inversion
Y1  - 2020
U6  - https://doi.org/10.1007/s11214-020-00744-0
SN  - 0038-6308
SN  - 1572-9672
VL  - 216
IS  - 8
PB  - Springer
CY  - Dordrecht
ER  -