نتایج جستجو برای: charging dust grains
تعداد نتایج: 79843 فیلتر نتایج به سال:
Interstellar polarization from aligned dust grains can be measured both in transmission at visible and near-infrared wavelengths and in emission at far-infrared and sub-mm wavelengths. These observations can help predict the behavior of foreground contamination of CMB polarimetry by dust in the Milky Way. Fractional polarization in emission from aligned dust grains will be at the higher range o...
We study the radial and vertical stability of dust grains launched with all charge-to-mass ratios at arbitrary distances from rotating planets with complex magnetic fields. We show that the aligned dipole magnetic field model analyzed by Jontof-Hutter and Hamilton (2012) is an excellent approximation in most cases, but that fundamentally new physics arises with the inclusion of non-axisymmetric...
We discuss the rotational excitation of small interstellar grains and the resulting electric dipole radiation from spinning dust. Attention is given to excitation and damping of grain rotation by: collisions with neutrals; collisions with ions; “plasma drag”; emission of infrared radiation; emission of electric dipole radiation; photoelectric emission; and formation of H2 on the grain surface. ...
If aspherical dust grains are immersed in an anisotropic radiation field, their temperature depends on the cross-sections projected in the direction of the anisotropy. It was shown that the temperature difference produces polarized thermal emission even without alignment, if the observer looks at the grains from a direction different from the anisotropic radiation. When the dust grains are alig...
We have used the Hubble Space Telescope Advanced Camera for Surveys coronagraph to make the first polarization maps of the AU Microscopii debris disk. The polarization rises from 5% at 20 AU to 40% at 80 AU. The polarization is perpendicular to the disk, indicating that the scattered light originates from micron-sized grains in an optically thin disk. Disk models show that interior to the ‘‘bir...
Identification by the Ulysses spacecraft of interstellar grains inside the planetary system provides a new window for the study of diffuse interstellar matter. Dust particles observed by Ulysses and confirmed by Galileo are more massive (≥ 10−13 g) than the ’classical’ interstellar grains. Even bigger grains (≈ 10−7 g) were observed in form of interstellar meteors. We analyze the consequences o...
Context. Theoretical arguments suggest that dust grains should grow in the dense cold parts of molecular clouds. Evidence of larger grains has so far been gathered in near/mid infrared extinction and millimeter observations. Interpreting the data is, however, aggravated by the complex interplay of density and dust properties (as well as temperature for thermal emission). Aims. Direct evidence o...
The dust probe DUSTY, first launched during the summer of 1994 (flights ECT–02 and ECT–07) from Andøya Rocket Range, northern Norway, was the first probe to unambiguously detect heavy charged mesospheric aerosols, from hereon referred to as dust. In ECT–02 the probe detected negatively charged dust particles in the height interval of 83 to 88.5 km. In this flight, the lower grid in the detector...
Recent observation of 850μm sub-mm polarization from T Tauri disks opens up the possibility of studying magnetic field structure within protostellar disks. The degree of polarization is around 3 % and the direction of polarization is perpendicular to the disk. Since thermal emission from dust grains dominates the spectral energy distribution at the sub-mm/FIR regime, dust grains are thought to ...
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