Results 11 to 20 of about 2,361 (168)
Extreme-Ultraviolet Emission from Solar Prominences
The Astrophysical Journal, 1972 Spectra and spectroheliograms of prominences have been obtained at wavelengths of 300 to 1400 A from instruments aboard the OSO 4 and OSO 6 spacecraft. Quiescent prominences appear in emission above the limb for all strong lines formed at temperatures below 300,000 K, but not at higher temperatures.
R. W. Noyes +5 more
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The Astrophysical Journal, 2022 The propagation direction and true velocity of a solar coronal mass ejection, which are among the most decisive factors for its geo-effectiveness, are difficult to determine through single-perspective imaging observations. Here we show that Sun-as-a-star
Yu Xu +5 more
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Asymmetries of solar coronal extreme ultraviolet emission lines [PDF]
Astronomy and Astrophysics, 2010 Astronomy & Astrophysics (accepted), 17 pages, 13 ...
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Emission lines of H2 in the extreme-ultraviolet solar spectrum
The Astrophysical Journal, 1978 A sunspot EUV spectrum covering the wavelength range from 1175 to 1714 A with high spatial and spectral resolution is examined which contains about 200 lines not previously reported in solar spectra. Many of the lines are identified as transitions in the Lyman bands of H2.
Jordan, C +4 more
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Modeling solar extreme ultraviolet irradiance variability using emission measure distributions
Geophysical Research Letters, 1996 We introduce a new model of solar irradiance variability at extreme ultraviolet (EUV) wavelengths. The model combines a spectral emission line database, solar emission measure distributions, and estimates from ground‐based solar images of the fraction of the Sun covered by the various types of activity to synthesize the irradiance.
H. P. Warren +4 more
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The Astrophysical Journal, 2023 The Kepler space telescope and Transiting Exoplanet Survey Satellite unveiled that Sun-like stars frequently host exoplanets. These exoplanets are subject to fluxes of ionizing radiation in the form of X-ray and extreme-ultraviolet (EUV) radiation that ...
Kosuke Namekata +5 more
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Measurements of extreme-ultraviolet emission-line profiles near the solar limb
The Astrophysical Journal, 1978 Line profiles of optically thin extreme-ultraviolet emission lines observed in a quiet sun region at positions within and above the white-light limb with the NRL slit spectrograph (S082-B) on Skylab are discussed. Absolute line intensities and full widths at half-maximum are presented for lines formed over the temperature range from about 10,000 to 22 ...
J. T. Mariska, U. Feldman, G. A. Doschek
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TWO COMPONENTS OF THE SOLAR CORONAL EMISSION REVEALED BY EXTREME-ULTRAVIOLET SPECTROSCOPIC OBSERVATIONS [PDF]
The Astrophysical Journal, 2011 Recent spectroscopic observations have revealed the ubiquitous presence of blueward asymmetries of emission lines formed in the solar corona and transition region. These asymmetries are most prominent in loop footpoint regions, where a clear correlation of the asymmetry with the Doppler shift and line width determined from the single-Gaussian fit is ...
Hui Tian +5 more
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Validation of Extreme Ultraviolet Emission Spectra During Solar Flares
, 2020 Abstract X-rays and extreme ultraviolet (EUV) emissions from solar flares rapidly change the physical composition of the Earth’s thermosphere and ionosphere, thereby causing space weather phenomena such as communication failures. To predict the effects of flare emissions on the Earth’s upper atmosphere, numerous empirical and physical models ...
Shohei Nishimoto +4 more
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Extreme ultraviolet emission lines of Ar XIV in solar active region and flare spectra [PDF]
Monthly Notices of the Royal Astronomical Society, 2003 New R-matrix calculations of electron impact excitation rates for transitions among the 2s 2 2p, 2s2p 2 and 2p 3 levels of Ar XIV are presented. These data are subsequently used to derive the theoretical electron density diagnostic emission-line intensity ratios R 1 = I(187.95 A)/I(194.41 A) and R 2 = I(257.40 A)/I(243.78 A) for a range of ...
Keenan, Francis +5 more
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