Search Publications
Dependence of the eruptive filaments dynamics on their length
Filippov, B.
We analyse numerically a model of eruption of a thin flux rope with the endpoints frozen in the photosphere. The flux rope is assumed to maintain a shape of partial current-carrying torus staying initially in equilibrium in the external dipolar magnetic field. There is an unstable equilibrium point, which can be reached by slow evolution of the sy…
In-flight radiometric calibration of the ExoMars TGO Colour and Stereo Surface Imaging System
Pajola, M.; Cremonese, G.; Da Deppo, V. +15 more
The Colour and Stereo Surface Science Imaging System (CaSSIS) of the ExoMars Trace Gas Orbiter returns on average twenty images per day of the Martian surface, most of them in 3 or 4 colours and some of them in stereo. CaSSIS uses a push-frame approach to acquire colour images, with four bandpass filters deposited directly above the sensor and an …
Estimating ion escape from unmagnetized planets
Holmstrom, Mats
We propose a new method to estimate ion escape from unmagnetized planets that combines observations and models. Assuming that upstream solar wind conditions are known, a computer model of the interaction between the solar wind and the planet is executed for different ionospheric ion production rates. This results in different amounts of mass loadi…
Improving the solar wind density model used in processing of spacecraft ranging observations
Pavlov, Dmitry; Aksim, Dan
Solar wind plasma as a cause of radio signal delay plays an important role in solar and planetary science. Early experiments studying the distribution of electrons near the Sun from spacecraft ranging measurements were designed so that the radio signal was passing close to the Sun. At present, processing of spacecraft tracking observations serves …
Implicit Solar Coronal Magnetohydrodynamic (MHD) Modeling with a Low-dissipation Hybridized AUSM-HLL Riemann Solver
Shen, Fang; Xiang, Changqing; Wang, Haopeng +2 more
In this paper, we develop a 3D implicit single-fluid magnetohydrodynamic (MHD) model to simulate the steady-state solar corona with a wide range of Mach numbers and low plasma β. We employ a low-dissipation advection upstream splitting method (AUSM) to calculate the convective flux in the regions of low Mach numbers for a high resolution, and hybr…
Dynamical Effect on Static Stability of the Venus Atmosphere Simulated Using a General Circulation Model: A Comparison With Radio Occultation Measurements
Tellmann, Silvia; Pätzold, Martin; Imamura, Takeshi +10 more
Distributions of temperature and static stability in the Venus atmosphere consistent with recent radio occultation measurements are reproduced using a general circulation model. A low-stability layer is maintained at low- and mid-latitudes at 50-60 km altitude and is sandwiched by high- and moderate-stability layers extending above 60 and below 50…
NuSTAR Spectral Analysis beyond 79 keV with Stray Light
Tomsick, J. A.; Wilms, J.; Buisson, D. J. K. +10 more
Due to the structure of the NuSTAR telescope, photons at a large off axis (>1°) can reach the detectors directly (stray light), without passing through the instrument optics. At these off-axis angles NuSTAR essentially turns into a collimated instrument and the spectrum can extend to energies above the Pt K edge (79 keV) of the multilayers, whi…
Relation between Black Hole Mass and Bulge Luminosity in Hard X-Ray Selected Type 1 AGNs
Ho, Luis C.; Barth, Aaron J.; Kim, Minjin +1 more
Using I-band images of 35 nearby (z < 0.1) type 1 active galactic nuclei (AGNs) obtained with Hubble Space Telescope, selected from the 70-month Swift-BAT X-ray source catalog, we investigate the photometric properties of the host galaxies. With a careful treatment of the point-spread function (PSF) model and imaging decomposition, we robustly …
Coronal and Chromospheric Emission in A-type Stars
Robrade, J.; Schneider, P. C.; Wolk, Scott J. +3 more
Cool stars on the main sequence generate X-rays from coronal activity, powered by a convective dynamo. With increasing temperature, the convective envelope becomes smaller and X-ray emission fainter. We present Chandra/HRC-I observations of four single stars with early A spectral types. Only the coolest star of this sample, τ 3 Eri (T <…
Spherical harmonic decomposition and interpretation of the shapes of the small Saturnian inner moons
Lainey, V.; Rambaux, N.; Cooper, N. +2 more
Context. The Cassini-Huygens space mission made a series of observations of Saturn's small satellites during its grand finale stage. These measurements were performed in order to study the shape, geology, and surface composition of the small satellites as well as to study the impact of the environment, in particular the rings, on these small bodie…