Romain Maggiolo

Radiation belt electron precipitation due to VLF transmitters: Satellite observations

In the Earth’s inner magnetosphere, the distribution of nenergetic electrons is controlled by pitch-angle scattering by nwaves. A category of Whistler waves originates from npowerful ground-based VLF transmitter signals in the nfrequency range 10–25 kHz. These transmissions are nobserved in space as waves of very narrow bandwidth. nHere we examine the significance of the VLF transmitter nNWC on the inner radiation belt using DEMETER satellite nglobal observations at low altitudes. We find that nenhancements in the 100–600 keV drift-loss cone nelectron fluxes at L values between 1.4 and 1.7 are linked nto NWC operation and to ionospheric absorption. Waves nand particles interact in the vicinity of the magnetic nequatorial plane. Using Demeter passes across the drifting ncloud of electrons caused by the transmitter; we find that n300 times more 200 keV electrons are driven into the ndrift-loss cone during NWC transmission periods than nduring non-transmission periods. The correlation between nthe flux of resonant electrons and the Dst index shows that nthe electron source intensity is controlled by magnetic storm nactivity.

ORIGIN OF MOLECULAR OXYGEN IN COMET 67P/CHURYUMOV–GERASIMENKO

Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with abundances in the 1-10% range by the ROSINA-DFMS instrument on board the Rosetta spacecraft. Here we find that the radiolysis of icy grains in low-density environments such as the presolar cloud may induce the production of large amounts of molecular oxygen. We also show that molecular oxygen can be efficiently trapped in clathrates formed in the protosolar nebula, and that its incorporation as crystalline ice is highly implausible because this would imply much larger abundances of Ar and N2 than those observed in the coma. Assuming that radiolysis has been the only O2 production mechanism at work, we conclude that the formation of comet 67P/Churyumov-Gerasimenko is possible in a dense and early protosolar nebula in the framework of two extreme scenarios: (1) agglomeration from pristine amorphous icy grains/particles formed in ISM and (2) agglomeration from clathrates that formed during the disks cooling. The former scenario is found consistent with the strong correlation between O2 and H2O observed in 67P/C-Gs coma while the latter scenario requires that clathrates formed from ISM icy grains that crystallized when entering the protosolar nebula.

The Delayed Time Response of Geomagnetic Activity to the Solar Wind

We investigate the lagged correlation between a selection of geomagnetic indices and solar wind parameters for a complete solar cycle, from 2000 to 2011. We first discuss the mathematical assumptio ...

The effect of radiogenic heating on the accretion of comet 67P/Churyumov-Gerasimenko

GERASIMENKO. A. Drouard, O. Mousis, P. Vernazza, J. I. Lunine, M., Monnereau, R. Maggiolo, K. Altwegg, H. Balsiger, J.-J. Berthelier, G. Cessateur, J. De Keyser, S. A. Fuselier, S. Gasc, A. Korth, T. Le Deun, U. Mall, B. Marty, H. Rème, M. Rubin, C.-Y. Tzou, J. H. Waite, and P. Wurz, Aix Marseille Université, CNRS, LAM (Laboratoire dAstrophysique de Marseille) UMR 7326, 13388, Marseille, France (e-mail: olivier.mousis@lam.fr), Department of Astronomy and Carl Sagan Institute, Space Sciences Building, Cornell University, Ithaca, USA, Université de Toulouse, UPS-OMP-CNRS, IRAP, Toulouse, France, Royal Belgian Institute for Space Aeronomy, BIRA-IASB, Brussels, Belgium, Physikalisches Institut, University of Bern, Bern, Switzerland, Center for Space and Habitability, University of Bern, Bern, Switzerland, LATMOS/IPSL-CNRS-UPMCUVSQ, Saint-Maur, France, Department of Space Science, Southwest Research Institute, San Antonio, USA, MaxPlanck-Institut für Sonnensystemforschung, Göttingen, Germany, Centre de Recherches Pétrographiques et Géochimiques, CRPG-CNRS, Université de Lorraine, Vandoeuvre lès Nancy, France.