نتایج جستجو برای: solar atmosphere
تعداد نتایج: 169582 فیلتر نتایج به سال:
The flow of energy through the solar atmosphere and the heating of the Sun's outer regions are still not understood. Here, we report the detection of oscillatory phenomena associated with a large bright-point group that is 430,000 square kilometers in area and located near the solar disk center. Wavelet analysis reveals full-width half-maximum oscillations with periodicities ranging from 126 to...
The structure and dynamics of the outer solar atmosphere are reviewed with emphasis on the role played by the magnetic field. Contemporary observations that focus on high resolution imaging over a range of temperatures, as well as UV, EUV and hard X-ray spectroscopy, demonstrate the presence of a vast range of temporal and spatial scales, mass motions, and particle energies present. By focussin...
An influence of solar irradiance variations on Earth’s surface climate has been repeatedly suggested, based on correlations between solar variability and meteorological variables1. Specifically, weaker westerly winds have been observed in winters with a less active sun, for example at the minimum phase of the 11-year sunspot cycle2–4. With some possible exceptions5,6, it has proved difficult fo...
Non-uniformities of plasma and magnetic field are known to cause electric currents in plasma. Electron density gradient causes diffusion current, electron temperature gradient — thermocurrent, gradient of magnetic field module — gradient current, curvature of magnetic field lines — centrifugal current. Being independent of electric field, the currents of non-uniformities may act as extraneous t...
We briefly review the status of radio observations of the solar atmosphere with an emphasis on relevance to stellar observations. 1. Radio Emission Mechanisms Solar radio observations are sensitive to virtually every feature of the solar atmosphere, covering a temperature range from the temperature minimum (5000 K) up to the soft Xray-emitting plasma produced by solar flares (> 107 K) and the m...
The sun is the primary driver of terrestrial atmospheric phenomena and energy source for the earth. It emits radiation over a large energy band and ejects highly energetic plasma fluxes of charged particles into space. The sun is an active star that (i) goes through a 12-year maximum-minimum emission cycle, (ii) has huge, non-periodic eruptions in solar flares and coronal mass ejections, and (i...
Long-duration observations of Neptune’s brightness in two visible wavelengths provide a disk-averaged estimate of its atmospheric aerosol. Brightness variations were previously associated with the 11-year solar cycle, through solar-modulated mechanisms linked with either ultra-violet (UV) or galactic cosmic ray (GCR) effects on atmospheric particles. Here we use a recently extended brightness d...
We show that 5-minute acoustic oscillations may resonantly convert into Alfvén waves in the β∼1 region of the solar atmosphere. Considering the 5-minute oscillations as pumping standing acoustic waves oscillating along unperturbed vertical magnetic field, we find on solving the ideal MHD equations that amplitudes of Alfvén waves with twice the period and wavelength of acoustic waves exponential...
The properties of the photosphere in magnetic and nonmagnetic regions, at two levels in the solar atmosphere, have been studied, using two virtually simultaneous time sequences of 109 mn duration of CCD images taken at the Vacuum Tower Telescope of the Sacramento Peak Observatory. The selected wavelengths correspond to the true continuum and to the wing of the MgIb1 line, where brightenings are...
Long-duration observations of Neptune's brightness at two visible wavelengths provide a disk-averaged estimate of its atmospheric aerosol. Brightness variations were previously associated with the 11-year solar cycle, through solar-modulated mechanisms linked with either ultraviolet or galactic cosmic ray (GCR) effects on atmospheric particles. Here, we use a recently extended brightness data s...
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