نتایج جستجو برای: chromosphere
تعداد نتایج: 926 فیلتر نتایج به سال:
We explore the response of the He ii 304 Å and He i 584 Å line intensities to electron beam heating in solar flares using radiative hydrodynamic simulations. Comparing different electron beams parameters, we found that the intensities of both He lines are very sensitive to the energy flux deposited in the chromosphere, or more specifically to the heating rate, with He ii 304 Å being more sensit...
Solar observations at sub-mm, mm and cm wavelengths offer a straightforward diagnostic of physical conditions in the solar atmosphere because they yield measurement brightness temperature which, for optically thick features, equals intrinsic - much unlike diagnostics other spectral ranges. The Atacama Large Millimeter sub-millimeter Array (ALMA) has therefore opened new, hitherto underexplored,...
Aims. We study chromospheric emission to understand the temperature stratification in the solar chromosphere. Methods. We observed the intensity profile of the Ca iiH line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope. We analyze over 10 line profiles from internetwork regions. For comparison with the observed profiles, we synthesize spectra for a variety o...
We present high-quality HST/GHRS spectra in the Hydrogen Lα spectral region of Vega and Sirius-A. Thanks to the signal-to-noise ratio achieved in these observations and to the similarity of the two spectra, we found clear evidence of emission features in the low flux region, λλ1190-1222Å. These emission lines can be attributed unambiguously to Fe ii and Cr ii transitions. In this spectral range...
Several mechanisms have been proposed to account for the formation of solar prominences or filaments, among which direct injection and evaporation-condensation models are two most popular ones. In model, cold plasma is ejected from chromosphere into corona along magnetic field lines; chromospheric heated over a million degrees evaporated corona, where accumulated finally reaches thermal instabi...
Context . Detailed numerical models of the chromosphere and corona are required to understand heating solar atmosphere. An accurate treatment is complicated by effects arising from non-local thermodynamic equilibrium (NLTE) radiative transfer. A small number strong, highly scattering lines dominate cooling in chromosphere. Additionally, recombination times ionised hydrogen longer than dynamical...
The physical processes causing energy exchange between the Sun's hot corona and its cool lower atmosphere remain poorly understood. The chromosphere and transition region (TR) form an interface region between the surface and the corona that is highly sensitive to the coronal heating mechanism. High-resolution observations with the Interface Region Imaging Spectrograph (IRIS) reveal rapid variab...
The Hanle and Zeeman effects in solar spicules: a novel diagnostic window on chromospheric magnetism
An attractive diagnostic tool for investigating the magnetism of the solar chromosphere is the observation and theoretical modeling of the Hanle and Zeeman effects in spicules, as shown in this letter for the first time. Here we report on spectropolarimetric observations of solar chromospheric spicules in the He i 10830 Å multiplet and on their theoretical modeling accounting for radiative tran...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید