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  • 1
    Publication Date: 2011-08-24
    Description: An improved method has been developed to evaluate element abundances from emission line intensities of thin plasmas, depending on the differential emission measure (DEM) of the source. Observations made by the Solar EUV Rocket Telescope and Spectrograph (SERTS) Rocket EUV Spectrograph are used to perform a detailed analysis of the DEM distribution for temperatures larger than 10(exp 5) K in a solar active region. Comparison of the DEM distributions obtained by means of lines from different elements allows the verification of relative abundances for the most common elements of the solar corona, and gives an abundance estimates for the minor components, such as Na, Al, Ar, Cr, Mn and Zn.
    Keywords: SOLAR PHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 14; 4; p. (4)163-(4)166
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  • 2
    Publication Date: 2004-12-03
    Description: New level population calculations for Fe-XIII are presented, and line intensities predicted. The extreme ultraviolet (EUV) lines are compared with the recent observations of the solar extreme ultraviolet rocket telescope and spectrograph (SERTS), and density estimates for the active region are given. Uses of the Fe-XIII lines are suggested, both for the sun and other stars, and the possibility of coordinating SOHO studies of EUV lines with ground based observations of Fe-XIII infrared lines is discussed.
    Keywords: SOLAR PHYSICS
    Type: ESA, Proceedings of 3rd SOHO Workshop on Solar Dynamic Phenomena and Solar Wind Consequences; p 417-420
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  • 3
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    In:  Other Sources
    Publication Date: 2011-08-16
    Description: Missions planned for OSO-8 are outlined. Instruments to be included on the satellite comprise a multichannel UV spectrometer, a high-resolution UV spectrometer, an X-ray crystal spectrometer and polarimeter, a hard X-ray telescope, a celestial X-ray spectrometer, a mapping X-ray heliometer, an extrasolar extreme UV monitor, and a soft X-ray telescope. The instruments make up a scientific payload that is larger, transmits data at a greater rate, can be pointed with higher accuracy, and has much better spatial and spectral resolution over a wider range of wavelengths than any payload carried by previous OSO satellites.
    Keywords: SOLAR PHYSICS
    Type: Sky and Telescope; 49; June 197
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  • 4
    Publication Date: 2011-08-16
    Description: Polarization measurements of solar X-ray events that were obtained with an instrument on OSO-7 are presented. The results appear to be consistent with the results of Tindo et al. on the existence and magnitudes of polarization. A comparison with polarization predictions when X-rays are produced by radial beams of electrons gives two examples of deviations from such a model.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 37; Aug. 197
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  • 5
    Publication Date: 2011-08-17
    Description: EUV (Fe XV at 284 A) and radio (at 169 and 408 MHz) observations were made of the coronal hole on May 31, 1973. An inhomogeneous model consisting of hot (a temperature of about 2 x 10 to the 6th K) elements covering 10% of the hole surface surrounded by regions of colder gas (a temperature of about 8 x 10 to the 5th K) is able to explain both observations.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 51; Jan
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  • 6
    Publication Date: 2011-08-17
    Description: Temperatures and temperature gradients for the outer corona are obtained from brightness gradients of EUV lines that were measured with the spectroheliograph on OSO-7. Brightness gradients show considerable deviations from isothermal model calculations that include collisional excitation and photoexcitation. A negative temperature gradient that gives both positive and negative ion-abundance gradients appears to be able to account for the discrepancy. For the 284-A of Fe XV, perhaps the strongest line from the outer corona, measurements during 1972 appear to be consistent with a temperature near 2.3 million K near the equator at about 1.3 solar radii from the solar center and with temperature-gradient values near -0.7 that extend from as low as 1.2 to about 1.8 solar radii. Temperatures from strong lines of Fe XIV and Fe XVI indicate that variations of about 200,000 K exist along lines of sight where emission is appreciable. There appears to be some agreement between these results and temperature measurements from ion abundances in the solar wind and the Doppler width of the 5303-A line.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 47; Apr. 197
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  • 7
    Publication Date: 2011-08-17
    Description: Data obtained by the OSO-7 spectroheliograph on strong XUV lines of five different Fe ions from the outer equatorial corona are presented. Interpretation of the data with a spherically symmetric model atmosphere gives average ion abundances for lines of sight at 0.3 solar radii from the limb. Fe XVI is usually more abundant than Fe XV, XIV, XII and IX, but there are times when Fe XII is more abundant than the other ions. The deviation of measured relative abundances of Fe XII, XIV, and XVI from predictions of ionization equilibrium at one temperature seems to indicate that there are appreciable temperature variations along lines of sight. Element abundances are very uncertain since they appear to depend so heavily on likely but unknown density irregularities along lines of sight.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 53; Aug. 197
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  • 8
    Publication Date: 2011-08-16
    Description: The abundance of Fe relative to H is obtained by using resonantly scattered intensities of lambda 284 of Fe XV that were measured with OSO-7 and resonantly scattered intensities of L-alpha of H I that were obtained by Gabriel (1971). Because of possible differences in electron densities along lines of sight for these non-simultaneous measurements and in relative calibrations, results are rather uncertain but still indicate that the average Fe abundance relative to H in the corona appears to be at least as large as a recent photospheric abundance. Some limitations in using this method for obtaining abundances are examined for future experiments with simultaneous measurements and well calibrated detectors.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 42; June 197
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  • 9
    Publication Date: 2011-08-16
    Description: The spectral composition and spatial distribution of equatorial coronal emission near 304 A is examined. Spectral scans indicate that the predominant line is from Si XI. Comparisons of observations with calculations of intensity changes with altitude indicate that collisional excitation is important near the sun but that photoexcitation becomes dominant beyond about 1.3 solar radii from the solar center. Observed and calculated intensities are in approximate agreement for abundances and electron densities that are within the range of observed values.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 43; Aug. 197
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  • 10
    Publication Date: 2011-08-19
    Description: Some of the advantages of coordinated observations with ground-based and space instrumentation in research on prominences are examined. The dynamical behavior of a prominence in transition zone lines (HRTS) and the coronal environment of a filament (SERTS) are discussed. Fe XIV and Si X line ratios were found to be important for NE diagnostic.
    Keywords: SOLAR PHYSICS
    Type: of the COSPAR 28th Plenary Meeting, The Hague, Netherlands, June 25-July 6, 1990. A91-47654 20-92) Advances in Space Research (ISSN 0273-1177); 255-258
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