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A Tale of “Two” Comets: The Primary Volatile Composition of Comet 2P/Encke Across Apparitions and Implications for Cometary Science

Vervack, Ronald J., Jr.; Kawakita, Hideyo; DiSanti, Michael A. +5 more

The highly favorable 2017 apparition of 2P/Encke allowed the first comprehensive comparison of primary volatile abundances in a given comet across multiple apparitions. This apparition offered opportunities to address pressing questions in cometary science, including investigating evolutionary and/or heliocentric distance (R _h) effects …

Models of Rosetta/OSIRIS 67P Dust Coma Phase Function

Lamy, P. L.; Lara, L. M.; Bertaux, J. -L. +39 more

The phase function of the dust coma of comet 67P has been determined from Rosetta/OSIRIS images. This function shows a deep minimum at phase angles near 100°, and a strong backscattering enhancement. These two properties cannot be reproduced by regular models of cometary dust, most of them based on wavelength-sized and randomly oriented aggregate …

FUV Spectral Signatures of Molecules and the Evolution of the Gaseous Coma of Comet 67P/Churyumov-Gerasimenko

Parker, Joel Wm.; Bertaux, Jean-Loup; Stern, S. Alan +10 more

The Alice far-ultraviolet imaging spectrograph onboard Rosetta observed emissions from atomic and molecular species from within the coma of comet 67P/Churyumov-Gerasimenko during the entire escort phase of the mission from 2014 August to 2016 September. The initial observations showed that emissions of atomic hydrogen and oxygen close to the surfa…

Bi-lobed Shape of Comet 67P from a Collapsed Binary

Nesvorný, David; Vokrouhlický, David; Parker, Joel

The Rosetta spacecraft observations revealed that the nucleus of comet 67P/Churyumov-Gerasimenko consists of two similarly sized lobes connected by a narrow neck. Here, we evaluate the possibility that 67P is a collapsed binary. We assume that the progenitor of 67P was a binary and consider various physical mechanisms that could have brought the b…

Ultraviolet Observations of Coronal Mass Ejection Impact on Comet 67P/Churyumov-Gerasimenko by Rosetta Alice

Parker, Joel Wm.; Bertaux, Jean-Loup; Stern, S. Alan +13 more

The Alice ultraviolet spectrograph on the European Space Agency Rosetta spacecraft observed comet 67P/Churyumov-Gerasimenko in its orbit around the Sun for just over two years. Alice observations taken in 2015 October, two months after perihelion, show large increases in the comet’s Lyβ, O I 1304, O I 1356, and C I 1657 Å atomic emission that init…