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  • Other Sources  (3)
  • 1990-1994  (3)
  • 1994  (3)
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  • 1990-1994  (3)
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  • 1
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    Abundance determination in solar active region (1994)
    In:  Other Sources
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    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
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Mg IX emission lines in an active region spectrum obtained with the Solar EUV Rocket Telescope and Spectrograph (SERTS) (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Theoretical electron-temperature-sensitive Mg IX emission line ratios are presented for R(sub 1) = I(443.96 A)/I(368.06 A), R(sub 2) = I(439.17 A)/I(368.06 A), R(sub 3) = I(443.37 A)/I(368.06 A), R(sub 4) = I(441.22 A)/I(368.06 A), and R(sub 5) = I(448.28 A)/I(368.06 A). A comparison of these with observational data for a solar active region, obtained during a rocket flight by the Solar EUV Rocket Telescope and Spectrograph (SERTS), reveals excellent agreement between theory and observation for R(sub 1) through R(sub 4), with discrepancies that average only 9%. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations, and also resolves discrepancies found previously when the theoretical results were compared with solar data from the S082A instrument on board Skylab. However in the case of R(sub 5), the theoretical and observed ratios differ by almost a factor of 2. This may be due to the measured intensity of the 448.28 A line being seriously affected by instrumental effects, as it lies very close to the long wavelength edge of the SERTS spectral coverage (235.46-448.76 A).
    Keywords: ASTRONOMY
    Type: Solar Physics (ISSN 0038-0938); 149; 2; p. 301-308
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    NASA TECHNICAL REPORTS
  • 3
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    Evidence of mass outflow in the low corona over a large sunspot (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An extreme ultraviolet (EUV) imaging spectrograph designed for sounding rocket flight has been used to search for velocity fields in the low solar corona. During a flight in May, 1989, we obtained emission line profile measurements along a chord through an active region on the Sun. Relative Doppler velocities were measured in emission lines of Mg IX, Fe XV, and Fe XVI with a sensitivity of 2-3 km/s at 350 A. The only Doppler shift appreciably greater than this level was observed in the line of Mg IX at 368.1 A over the umbra of the large sunspot. The maximum shift measured at that location corresponded to a velocity toward the observer of 14 plus or minus 3 km/s relative to the mean of measurements in that emission line made elsewhere over the active region. The magnetic field in the low corona was aligned to within 10 deg of the line of sight at the location of maximum Doppler shift. Depending on the magnetic field geometry, this mass outflow could either re-appear as a downflow of material in distant footprints of closed coronal loops or, if along open field lines, could contribute to the solar wind. The site of the sunspot was near a major photospheric magnetic field boundary. Such boundaries have been associated with low-speed solar winds as observed in interplanetary plasmas.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 14; 4; p. (4)61-(4)64
    Format: text
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    NASA TECHNICAL REPORTS
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