Related papers: Models of OH Maser Variations in U Her
Within the 'Medicina/Effelsberg H2O maser monitoring program' we observed U Her and RR Aql at 22-GHz for about two decades between 1990 and 2011, with a gap between 1997 and 2000 in the case of RR Aql. In addition, maps were obtained in the…
Emission in spectral lines can provide unique information on interstellar turbulence. Doppler shifts due to supersonic motions contain information on turbulent velocity field which is otherwise difficult to measure. However, the problem of…
Small-scale magnetic turbulence observed by the Cluster spacecraft in the plasma sheet is investigated by means of a wavelet estimator suitable for detecting distinct scaling characteristics even in noisy measurements. The spectral…
Recent studies provide evidence for the multi-scale nature of magnetic turbulence in the plasma sheet. Wavelet methods represent modern time series analysis techniques suitable for the description of statistical characteristics of…
We present our past and current long-term monitoring program of water masers in the circumstellar envelopes of evolved stars, augmented by occasional interferometric observations. Using as example the Mira-variable U Her, we identify three…
H$_2$O maser emission at 22 GHz in the circumstellar envelope is one of the good tracers of detailed physics and kinematics in the mass loss process of asymptotic giant branch stars. Long-term monitoring of an H$_2$O maser spectrum with…
Observations show that 1612 MHz masers of OH/IR stars can fade on a timescale of a decade. This fading is probably associated with the switch from rapid mass loss, which is ultimately linked with an internal He-shell flash, to the much…
The nature of MHD turbulence is analyzed through both temporal and spatial magnetic fluctuation spectra. A magnetically turbulent plasma is produced in the MHD wind-tunnel configuration of the Swarthmore Spheromak Experiment (SSX). The…
This work presents a new theoretical and numerical model describing all possible linear interactions between upper-hybrid wave turbulence and random density fluctuations in a solar wind plasma; not only linear processes as wave reflection,…
Plasma turbulence involves complex, nonlinear interactions of electromagnetic fields and charged particles across multiple scales. Studying these phenomena in space plasmas, like the solar wind, is facilitated by the intrinsic scale…
Radiative diagnostics of high-energy density plasmas is addressed in this paper. We propose that the radiation produced by energetic particles in small-scale magnetic field turbulence, which can occur in laser-plasma experiments,…
Observations of ion-scale (k_y*rho_i <= 1) density turbulence of relative amplitude dn_e/n_e <= 0.2% are available on the Mega Amp Spherical Tokamak (MAST) using a 2D (8 radial x 4 poloidal channel) imaging Beam Emission Spectroscopy (BES)…
The dispersion equation, describing the instability development of vortex turbulence excitation in cylindrical plasma in crossed radial electric and axial magnetic fields with taking into account the longitudinal inhomogeneity and finite…
Magnetohydrodynamic (MHD) plasma turbulence is believed to play a vital role in the production of energetic electrons during solar flares and the non-thermal broadening of spectral lines is a key sign of this turbulence. Here, we determine…
We consider astrophysical maser radiation that is created in the presence of mildly supersonic, magnetohydrodynamic (MHD) turbulence. The focus is on the OH masers for which the magnetic field is strong enough that the separations of the…
Several works have recently shown that there is an important extra line-broadening (usually called $macroturbulence$) affecting the spectra of O and B Supergiants that adds to stellar rotation. So far, the only (very recent) physical…
Plasma turbulence is investigated using high-resolution ion velocity distributions measured by the Magnetospheric Multiscale Mission (MMS) in the Earth's magnetosheath. The particle distribution is highly structured, suggesting a…
This work presents an analytical investigation of anomalous diffusion and turbulence in a dusty plasma monolayer, where energy transport across scales leads to the spontaneous formation of spatially disordered patterns. Many-body…
We present thirteen epochs of near-infrared (0.8-5 micron) spectroscopic observations of the pre-transitional, "gapped" disk system in SAO 206462 (=HD 135344B). In all, six gas emission lines (including Br gamma, Pa beta, and the 0.8446…
The objective of this paper is to unravel any relations that may exist between turbulent shear flows and statistical mechanics, through a detailed numerical investigation in the simplest case where both can be well defined. The shear flow…