Search Publications
Chromospheric evaporation in sympathetic coronal bright points
Ji, H. S.; Zhang, Q. M.
Context. Chromospheric evaporation is a key process in solar flares that has been extensively investigated using spectroscopic observations. However, direct soft X-ray (SXR) imaging of the process is rare, especially in remote brightenings associated with the primary flares that have recently attracted a great deal of attention.
Aims: We inte…
On the hadronic γ-ray emission from tycho's supernova remnant.
Zhang, X.; Chen, Y.; Li, H. +1 more
Hadronic γ-ray emission from supernova remnants (SNRs) is an important tool to test shock acceleration of cosmic-ray protons. Tycho is one of nearly a dozen Galactic SNRs which are suggested to emit hadronic γ-ray emission. Among them, however, it is the only one in which the hadronic emission is proposed to arise from the interaction with a low-d…
A self-consistent chemically stratified atmosphere model for the roAp star 10 Aquilae
Shulyak, D.; Kochukhov, O.; Weiss, W. +3 more
Context. Chemically peculiar A-type (Ap) stars are a subgroup of the CP2 stars that exhibit anomalous overabundances of numerous elements, e.g. Fe, Cr, Sr, and rare earth elements. The pulsating subgroup of Ap stars, the roAp stars, present ideal laboratories to observe and model pulsational signatures, as well as the interplay of the pulsations w…
Observations of polar cap flow channel and plasma sheet flow bursts during substorm expansion
Juusola, L.; PitkäNen, T.; Aikio, A. T.
We present the first simultaneous observations of an enhanced polar cap flow impinging on the nightside polar cap boundary (PCB), two flow bursts in the plasma sheet and a conjugate ionospheric flow burst within the auroral oval. The ionospheric measurements on 3 September 2006 were made by the European Incoherent Scatter (EISCAT) radars and the m…
INTEGRAL observations of SS433: system's parameters and nutation of supercritical accretion disc
Sunyaev, R. A.; Postnov, K. A.; Cherepashchuk, A. M. +3 more
Based on multiyear INTEGRAL observations of SS433 in 2003-2011, a composite IBIS/ISGRI 18-60 keV orbital light curve is constructed around zero precessional phases ψpr = 0 at the maximum accretion disc opening angle. It shows a peculiar shape with significant excess near the orbital phase φorb = 0.25, which is not seen in the…
Experimental CO2 absorption coefficients at high pressure and high temperature
Piccioni, Giuseppe; Adriani, Alberto; Grassi, Davide +2 more
Here we present a laboratory study of CO2 absorption spectra, obtained at high temperatures and pressures, similar to those encountered in the Venusian atmosphere. These spectra have been recorded using a Fourier Transform InfraRed (FT-IR) spectrometer , which is equipped to operate from 800 to 30,000 cm-1 (0.33-12.5 µm…
Star-planet-debris disc alignment in the HD 82943 system: is planetary system coplanarity actually the norm?
Bryden, G.; Wyatt, M. C.; Kennedy, G. M. +2 more
Recent results suggest that the two planets in the HD 82943 system are inclined to the sky plane by 20 ± 4°. Here, we show that the debris disc in this system is inclined by 27 ± 4°, thus adding strength to the derived planet inclinations and suggesting that the planets and debris disc are consistent with being aligned at a level similar to the So…
Gravitational Conundrum? Dynamical Mass Segregation versus Disruption of Binary Stars in Dense Stellar Systems
Deng, Licai; de Grijs, Richard; Li, Chengyuan +4 more
Upon their formation, dynamically cool (collapsing) star clusters will, within only a few million years, achieve stellar mass segregation for stars down to a few solar masses, simply because of gravitational two-body encounters. Since binary systems are, on average, more massive than single stars, one would expect them to also rapidly mass segrega…
Gyrosurfing Acceleration of Ions in Front of Earth's Quasi-parallel Bow Shock
Dandouras, Iannis; Khotyaintsev, Yuri V.; Agapitov, Oleksiy +4 more
It is well known that shocks in space plasmas can accelerate particles to high energies. However, many details of the shock acceleration mechanism are still unknown. A critical element of shock acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently…
Polarization and Compressibility of Oblique Kinetic Alfvén Waves
Passot, T.; Goldstein, M. L.; Zank, G. P. +3 more
It is well known that a complete description of the solar wind requires a kinetic description and that, particularly at sub-proton scales, kinetic effects cannot be ignored. It is nevertheless usually assumed that at scales significantly larger than the proton gyroscale rL , magnetohydrodynamics or its extensions, such as Hall-MHD and t…