@article{MarschallSkorovZakharovetal.2020,
  author    = {Marschall, Raphael and Skorov, Yuri and Zakharov, Vladimir and Rezac, Ladislav and Gerig, Selina-Barbara and Christou, Chariton and Dadzie, S. Kokou and Migliorini, Alessandra and Rinaldi, Giovanna and Agarwal, Jessica and Vincent, Jean-Baptiste and Kappel, David},
  title     = {Cometary comae-surface links the physics of gas and dust from the surface to a spacecraft},
  series = {Space science reviews},
  volume    = {216},
  journal   = {Space science reviews},
  number    = {8},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {0038-6308},
  doi       = {10.1007/s11214-020-00744-0},
  pages     = {53},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{TosiCapaccioniCapriaetal.2019,
  author    = {Tosi, Federico and Capaccioni, F. and Capria, M. T. and Mottola, Stefano and Zinzi, A. and Ciarniello, M. and Filacchione, G. and Hofstadter, M. and Fonti, S. and Formisano, M. and Kappel, David and K{\"u}hrt, E. and Leyrat, C. and Vincent, J-B and Arnold, G. and De Sanctis, M. C. and Longobardo, Andrea and Palomba, E. and Raponi, A. and Rousseau, Batiste and Schmitt, Bernard and Barucci, Maria Antonietta and Bellucci, Giancarlo and Benkhoff, Johannes and Bockelee-Morvan, D. and Cerroni, P. and Combe, J-Ph and Despan, D. and Erard, St{\´e}phane and Mancarella, F. and McCord, T. B. and Migliorini, Alessandra and Orofino, V and Piccioni, G.},
  title     = {The changing temperature of the nucleus of comet 67P induced by morphological and seasonal effects},
  series = {Nature astronomy},
  volume    = {3},
  journal   = {Nature astronomy},
  number    = {7},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2397-3366},
  doi       = {10.1038/s41550-019-0740-0},
  pages     = {649 -- 658},
  year      = {2019},
  abstract  = {Knowledge of the surface temperature distribution on a comet's nucleus and its temporal evolution at different timescales is key to constraining its thermophysical properties and understanding the physical processes that take place at and below the surface. Here we report on time-resolved maps of comet 67P/Churyumov-Gerasimenko retrieved on the basis of infrared data acquired by the Visible InfraRed and Thermal Imaging Spectrometer (VIRTIS) onboard the Rosetta orbiter in 2014, over a roughly two-month period in the pre-perihelion phase at heliocentric distances between 3.62 and 3.31 au from the Sun. We find that at a spatial resolution ≤15 m per pixel, the measured temperatures point out the major effect that self-heating, due to the complex shape of the nucleus, has on the diurnal temperature variation. The bilobate nucleus of comet 67P also induces daytime shadowing effects, which result in large thermal gradients. Over longer periods, VIRTIS-derived temperature values reveal seasonal changes driven by decreasing heliocentric distance combined with an increasing abundance of ice within the uppermost centimetre-thick layer, which implies the possibility of having a largely pristine nucleus interior already in the shallow subsurface},
  language  = {en}
}