SPACEOBS kickoff

SPACEOBS : a space incubator funded by University Paris-Saclay started this January. The first part of the project is for 2017. Funding is 700k€.

SPACEOBS will develop inovative activities in four essential directions:

  • MultiScale multi-spacecraft data analysis (WP1)
  • Coupling simulations with observations (WP2)
  • New generation instrument design (WP3)
  • Public outreach and teaching (WP4)

I’m co-leading the work package 1

Cold ion heating at the dayside magnetopause during magnetic reconnection

Cold ion heating at the dayside magnetopause during magnetic reconnection

Geophysical Research Letters, Volume 43, Issue 1, pp. 58-66 DOI :

Toledo-Redondo, S.; André, M.; Vaivads, A.; Khotyaintsev, Yu. V.; Lavraud, B.; Graham, D. B.; Divin, A.; Aunai, N.

Cold ions of ionospheric origin are known to be present in the magnetospheric side of the Earth’s magnetopause. They can be very abundant, with densities up to 100 cm-3. These cold ions can mass load the magnetosphere, changing global parameters of magnetic reconnection, like the Alfvén speed or the reconnection rate. In addition they introduce a new length scale related to their gyroradius and kinetic effects which must be accounted for. We report in situ observations of cold ion heating in the separatrix owing to time and space fluctuations of the electric field. When this occurs, the cold ions are preheated before crossing the Hall electric field barrier. However, when this mechanism is not present cold ions can be observed well inside the reconnection exhaust. Our observations suggest that the perpendicular cold ion heating is stronger close to the X line owing to waves and electric field gradients linked to the reconnection process.

BV technique for investigating 1-D interfaces

BV technique for investigating 1-D interfaces

Published in Journal of Geophysical Research

Dorville Nicolas, Belmont Gerard, Rezeau Laurence, Aunai Nicolas Retinò, Alessandro

To investigate the internal structure of the magnetopause with spacecraft data, it is crucial to be able to determine its normal direction and to convert the measured time series into spatial profiles. We propose here a new single-spacecraft method, called the BV method, to reach these two objectives. Its name indicates that the method uses a combination of the magnetic field (B) and velocity (V) data. The method is tested on simulation and on Cluster data, and a short overview of the possible products is given. We discuss its assumptions and show that it can bring a valuable improvement with respect to previous methods.