Search Publications
Seasonal variations in source regions of the dust jets on comet 67P/Churyumov-Gerasimenko
Jorda, L.; Lara, L. M.; Bertaux, J. -L. +43 more
Aims: We investigate the surface distribution of the source regions of dust jets on comet 67P/Churyumov-Gerasimenko as a function of time.
Methods: The dust jet source regions were traced by the comprehensive imaging data set provided by the OSIRIS scientific camera.
Results: We show in detail how the projected footpoints of the dus…
Spectral Signatures of Adiabatic Electron Acceleration at Saturn Through Corotation Drift Cancelation
Krupp, N.; Roussos, E.; Zong, Q. G. +3 more
The energetic electron spectra of Saturn's radiation belts are studied using Cassini's 13 years of measurements by the Magnetosphere Imaging Instrument/Low Energy Magnetospheric Measurement System detector. We find that between L shells (L) of 10 and 4.5 the differential flux spectrum of 0.3- to 1.6-MeV electrons evolves from a single power law to…
Onset and Evolution of the Oblique, Resonant Electron Firehose Instability in the Expanding Solar Wind Plasma
Velli, Marco; Innocenti, Maria Elena; Tenerani, Anna +1 more
A double adiabatically expanding solar wind would quickly develop large parallel to perpendicular temperature anisotropies in electrons and ions that are not observed. One reason is that firehose instabilities would be triggered, leading to an ongoing driving/saturation evolution mechanism. We verify this assumption here for the first time for the…
Kinetic Monte Carlo Model for the Precipitation of High-Energy Protons and Hydrogen Atoms into the Atmosphere of Mars with Taking into Account the Measured Magnetic Field
Gérard, J. -C.; Hubert, B.; Shematovich, V. I. +1 more
Results of model computations of the interaction of the high-energy protons and hydrogen atoms (H/H+) precipitating into the Martian atmosphere are presented. These computations were performed using a modification of the kinetic Monte Carlo model developed earlier for the analysis of the data from the MEX/ASPERA-3 instrument onboard the…
An equatorial thermal wind equation: Applications to Jupiter
Wong, Michael H.; Tollefson, Joshua; Marcus, Philip S. +1 more
To relate the vertical wind shear to horizontal temperature gradients at and near the equator, we derive an "Equatorial Thermal Wind Equation" (EQTWE) using a minimum set of assumptions that are easily satisfied for the atmospheres of all the giant planets and Earth. Similar to the textbook Thermal Wind Equation (TWE), the EQTWE requires a small R…
The young stellar population in NGC 247. Main properties and hierarchical clustering
Baume, G.; Rodríguez, M. J.; Feinstein, C.
Aims: We seek to investigate the characteristics of the young stellar population in the spiral galaxy NGC 247. In particular, we focused our attention in its hierarchical clustering distributions and the properties of the smallest groups.
Methods: We used multiband Hubble Space Telescope (HST) data from three fields covering more than ha…
A black box for dark sector physics: predicting dark matter annihilation feedback with conditional GANs
Lewis, Geraint F.; List, Florian; Bhat, Ishaan
Traditionally, incorporating additional physics into existing cosmological simulations requires re-running the cosmological simulation code, which can be computationally expensive. We show that conditional Generative Adversarial Networks (cGANs) can be harnessed to predict how changing the underlying physics alters the simulation results. To illus…
Variability of Intra-D Ring Azimuthal Magnetic Field Profiles Observed on Cassini's Proximal Periapsis Passes
Dougherty, M. K.; Cowley, S. W. H.; Bunce, E. J. +4 more
We overview the properties of the azimuthal magnetic fields observed during the periapsis passes of the final 23 orbits of the Cassini spacecraft, including the partial orbit at end of mission, on near equatorial field lines passing inside of Saturn's D ring. The signatures are variable in form and amplitude, though generally approximately symmetr…
Asteroseismic constraints on active latitudes of solar-type stars: HD 173701 has active bands at higher latitudes than the Sun
Chaplin, William J.; Davies, Guy R.; Miglio, Andrea +6 more
We present a new method for determining the location of active bands of latitude on solar-type stars, which uses stellar-cycle-induced frequency shifts of detectable solar-like oscillations. When near-surface activity is distributed in a non-homogeneous manner, oscillation modes of different angular degree and azimuthal order will have their frequ…
Resonant instabilities of kinetic Alfvén waves in the Earth's magnetosphere with superthermal electrons
Lakhina, G. S.; Singh, S. V.; Barik, K. C.
A theoretical plasma model for the generation of kinetic Alfvén waves (KAWs), having background Maxwellian ions, κ-electrons, and drifting Maxwellian beam ions, is discussed. The ion beam streams along the ambient magnetic field, whereas velocity shear is perpendicular to it. The role played by nonthermal electrons in the excitation of resonant KA…