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A Study on White Dwarf Masses in Cataclysmic Variables Based on XMM-Newton and Suzaku Observations
Li, Xiang-Dong; Xu, Xiao-Jie; Yu, Zhuo-Li
The distribution of the mass of white dwarfs (WDs) is one of the fundamental questions in the field of cataclysmic variables (CVs). In this work, we make a systematical investigation on the WD masses in two subclass of CVs: intermediate polars (IPs) and non-magnetic CVs in the solar vicinity based on the flux ratios of Fe XXVI-Lyα to Fe XXV-Heα em…
The Quasar CTD 135 Is Not a Compact Symmetric Object
Frey, Sándor; An, Tao; Gabányi, Krisztina É.
The radio-loud quasar CTD 135 (2234+282, J2236+2828) has been proposed as a candidate compact symmetric object (CSO), based on its symmetric radio structure revealed by multi-frequency very long baseline interferometry (VLBI) imaging observations on milliarcsec angular scales. CSOs are known as young jetted active galactic nuclei (AGN) whose relat…
On the physical size of the Milky Way globular cluster NGC 7089 (M2)
Piatti, Andrés E.
We study the outer regions of the Milky Way globular cluster NGC 7089 based on new Dark Energy Camera observations. The resulting background-cleaned stellar density profile reveals the existence of an extended envelope. We confirm previous results that cluster stars are found out up to ~1° from the cluster's centre, which is nearly three times the…
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…