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  • 1995-1999  (7)
  • 1997  (7)
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  • 1995-1999  (7)
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  • 1
    Electronic Resource
    Electronic Resource
    FIRST RESULTS OF THE SUMER TELESCOPE AND SPECTROMETER ON SOHO – I. Spectra and Spectroradiometry (1997)
    Springer
    Solar physics 170 (1997), S. 75-104 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract SUMER – the Solar Ultraviolet Measurements of the Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) – observed its first light on January 24, 1996, and subsequently obtained a detailed spectrum with detector B in the wavelength range from 660 to 1490 Å (in first order) inside and above the limb in the north polar coronal hole. Using detector A of the instrument, this range was later extended to 1610 Å. The second-order spectra of detectors A and B cover 330 to 805 Å and are superimposed on the first-order spectra. Many more features and areas of the Sun and their spectra have been observed since, including coronal holes, polar plumes and active regions. The atoms and ions emitting this radiation exist at temperatures below 2 × 106 K and are thus ideally suited to investigate the solar transition region where the temperature increases from chromospheric to coronal values. SUMER can also be operated in a manner such that it makes images or spectroheliograms of different sizes in selected spectral lines. A detailed line profile with spectral resolution elements between 22 and 45 mÅ is produced for each line at each spatial location along the slit. From the line width, intensity and wavelength position we are able to deduce temperature, density, and velocity of the emitting atoms and ions for each emission line and spatial element in the spectroheliogram. Because of the high spectral resolution and low noise of SUMER, we have been able to detect faint lines not previously observed and, in addition, to determine their spectral profiles. SUMER has already recorded over 2000 extreme ultraviolet emission lines and many identifications have been made on the disk and in the corona.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004923511980
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    FIRST RESULTS OF THE SUMER TELESCOPE AND SPECTROMETER ON SOHO – II. Imagery and Data Management (1997)
    Springer
    Solar physics 170 (1997), S. 105-122 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract SUMER – Solar Ultraviolet Measurements of Emitted Radiation – is not only an extreme ultraviolet (EUV) spectrometer capable of obtaining detailed spectra in the range from 500 to 1610 Å, but, using the telescope mechanisms, it also provides monochromatic images over the full solar disk and beyond, into the corona, with high spatial resolution. We report on some aspects of the observation programmes that have already led us to a new view of many aspects of the Sun, including quiet Sun, chromospheric and transition region network, coronal hole, polar plume, prominence and active region studies. After an introduction, where we compare the SUMER imaging capabilities to previous experiments in our wavelength range, we describe the results of tests performed in order to characterize and optimize the telescope under operational conditions. We find the spatial resolution to be 1.2 arc sec across the slit and 2 arc sec (2 detector pixels) along the slit. Resolution and sensitivity are adequate to provide details on the structure, physical properties, and evolution of several solar features which we then present. Finally some information is given on the data availability and the data management system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004994702333
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Doppler Shifts in the Quiet-Sun Transition Region and Corona Observed with Sumer on Soho (1997)
    Springer
    Solar physics 175 (1997), S. 349-374 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract New observations of systematic red shifts of transition region and coronal lines obtained with SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on SOHO (the Solar and Heliospheric Observatory) are presented. With the extensive wavelength coverage of SUMER it is possible to extend the measurements of the red shifts to much higher temperatures compared to previous instruments. We find lines formed in the upper transition region (e.g. Ov, Sv, and Svi) to be red-shifted similar to lower temperature lines (T ≤ 1.8 x 10-5 K). Even hotter lines such as Ovi, Neviii and Mgx show systematic red shifts on the order of 5 km s-1 in the quiet Sun. This is a new and significant result since previous measurements of the red shifts were less well constrained. The behavior of the red shifts above T = 10-5 K has been somewhat controversial. In some earlier investigations the magnitude of the red shift has been found to increase with temperature, reaching a maximum at T = 10-5 K and then to decrease toward higher temperatures. Thus, our results will put new constraints on theoretical models. The measured shifts are compared to recent observations of red-shifted emission in stellar spectra obtained with the Hubble Space Telescope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004985226553
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  • 4
    Electronic Resource
    Electronic Resource
    Observations of Polar Plumes with the Sumer Instrument on Soho (1997)
    Springer
    Solar physics 175 (1997), S. 375-391 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present new observations of O vi 1032 Å line profiles in polar plumes, and inter-plume regions, on the disk and above the limb in the north coronal hole obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) instrument on the SOHO (Solar and Heliospheric Observatory) spacecraft. On 22 May 1996, a 5 x 5 arc min spectroheliogram was scanned above the north polar coronal hole with the entrance slit extending from 1.03 to 1.33 solar radii with 1.5 arc sec spatial resolution and ≈ 0.044 Å per pixel spectral resolution in the wavelength range 1020–1040 Å. Detailed plume structure in O vi 1032 Å can be seen extending beyond 1.3 solar radii, with intensities in the plume regions 10–50% brighter, but line widths 10–15% narrower, than the inter-plume regions. Possible explanations for this observed anti-correlation between line width and intensity in the plume and inter-plume regions are discussed. We conclude that the source of the high-speed solar wind may not be polar plumes, but the inter-plume lanes associated with open magnetic field regions of the chromospheric network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004959324214
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  • 5
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    Systematic redshifts in the quiet sun transition region and corona observed with SUMER on SOHO (1997)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The observations of systematic redshifts of the transition region and coronal lines, obtained with the solar ultraviolet measurements of emitted radiation (SUMER) device onboard the Solar and Heliospheric Observatory (SOHO), are reported on. The results indicate that the redshifts are present even in the upper transition region. The lack of systematic blue shifts in Mg X lines raises the question on the origin of the solar wind. The observations of the solar ultraviolet spectrum with high resolution spectrometers demonstrated that there is a need for improved measurements of laboratory wavelengths of a number of spectral elements.
    Keywords: Solar Physics
    Type: ; 229-234
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    A search for the coronal origins of fast solar wind streams during the whole sun month period (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: The solar wind streams observed from the Solar and Heliospheric Observatory (SOHO) and Ulysses, WIND spacecraft during the whole solar month are discussed. These solar wind streams, with speeds in excess of 500 km/s, were detected from 10 August to 8 September 1996. The data covering Carrington rotations 1912 and 1913 are presented. The magnetic field azimuthal angle observations at 1 AU from WIND show that all the streams are associated with outward fields near the sun. The stream structure near 320 deg was associated with the central meridian passage of a coronal hole. The Fe XIV ground based observations show a region of low intensity in the zero to 170 deg longitude. The question of whether the streams arise from equatorial features or represent flows coming from higher latitude features is not solved.
    Keywords: Solar Physics
    Type: ; 511
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Highlights of the SUMER observations on SOHO (1997)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: The solar ultraviolet measurement of emitted radiation (SUMER) observational program provides continuous observations of the solar disk and the low corona off-limb since 24 January 1996. The achievements of the observational program to date are reviewed. Examples of results from various researchers are presented and discussed. The SUMER instrument and its performance onboard the Solar and Heliospheric Observatory (SOHO) are summarized.
    Keywords: Solar Physics
    Type: Proceedings of the 5th SOHO Workshop on 'The Corona and Solar Wind Near Minimum Activity'; 17-28; ESA-SP-404
    Format: text
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    NASA TECHNICAL REPORTS
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