Search Publications
Is Titan's shape caused by its meteorology and carbon cycle?
Sotin, C.; Choukroun, M.
Titan's shape is characterized by a difference between the long equatorial radius and the polar radius that is several hundred meters larger than that predicted by the flattening due to its spin rate. The North polar region is covered by large mare filled with hydrocarbons, including ethane. Moreover global circulation models predict ethane precip…
Gravity waves, cold pockets and CO2 clouds in the Martian mesosphere
Forget, F.; González-Galindo, F.; Spiga, A. +1 more
Many independent measurements have shown that extremely cold temperatures are found in the Martian mesosphere. These mesospheric “cold pockets” may result from the propagation of atmospheric waves. Recent observational achievements also hint at such cold pockets by revealing mesospheric clouds formed through the condensation of CO2, the…
Earth-based detection of Uranus' aurorae
André, N.; Dougherty, M. K.; Cecconi, B. +16 more
This study is based on multi-planet multi-wavelength observations of planetary aurorae throughout the heliosphere, acquired along the propagation path of a series of consecutive interplanetary shocks. The underlying motivation to track the shocks was to increase the probability of detection of auroral emissions at Uranus. Despite several Earth-bas…
Magnetotail dipolarization front and associated ion reflection: Particle-in-cell simulations
Shay, M. A.; Wu, P.
For the Earth magnetotail, the Svenes et al. (2008) statistical study infers the lobe density to be highly variable, in the range of 0.007-0.092 cm-3. Such lobe density variation modifies reconnection diffusion region physical processes and reconnection rate drastically. This letter addresses observable reconnection signatures in the vi…
Bursty escape fluxes in plasma sheets of Mars and Venus
Fedorov, A.; Barabash, S.; Lundin, R. +5 more
High resolution measurements of plasma in the plasma sheets of Mars and Venus performed by almost identical plasma instruments ASPERA-3 on the Mars Express spacecraft and ASPERA-4 on Venus Express reveal similar features of bursty fluxes of escaping planetary ions. A period of bursts lasts about 1-2 min. Simultaneous magnetic field measurements on…
A clear view of the multifaceted dayside ionosphere of Mars
Tellmann, Silvia; Pätzold, Martin; Häusler, Bernd +10 more
By examining electron density profiles from the Mars Express Radio Science Experiment MaRS, we show that the vertical structure of the dayside ionosphere of Mars is more variable and more complex than previously thought. The top of the ionosphere can be below 250 km (25% occurrence rate) or above 650 km (1%); the topside ionosphere can be well-des…
Detection of negative ions in the deep ionosphere of Titan during the Cassini T70 flyby
Wahlund, J. -E.; Edberg, N. J. T.; Ågren, K.
We present radio and plasma wave science (RPWS) Langmuir probe (LP) observations that give evidence for a population of heavy, negative ions at altitudes below 900 km in Titan's ionosphere during the Cassini T70 flyby. The negative ion density in this region is comparable to, or higher than, the electron density of 760 cm-3. Both positi…
Can solar wind viscous drag account for coronal mass ejection deceleration?
Subramanian, Prasad; Lara, Alejandro; Borgazzi, Andrea
The forces acting on solar Coronal Mass Ejections (CMEs) in the interplanetary medium have been evaluated so far in terms of an empirical drag coefficient CD ∼ 1 that quantifies the role of the aerodynamic drag experienced by a typical CME due to its interaction with the ambient solar wind. We use a microphysical prescription for viscos…
Electron pitch-angle diffusion in radiation belts: The effects of whistler wave oblique propagation
Krasnoselskikh, V.; Breuillard, H.; Agapitov, O. +2 more
We calculated the electron pitch-angle diffusion coefficients in the outer radiation belt for L-shell ∼4.5 taking into account the effects of oblique whistler wave propagation. The dependence of the distribution of the angle θ between the whistler wave vector and the background magnetic field on magnetic latitude is modeled after statistical resul…
On the ionospheric source region of cold ion outflow
Fränz, M.; Wei, Y.; Daly, P. W. +8 more
Recent studies have shown that low energy ions constitute a significant part of the total ion population in the Earth's magnetosphere. In this study, we have used a comprehensive data set with measurements of cold (total energy less than 70 eV) ion velocity and density to determine their source. This data set is derived from Cluster satellite meas…