Search Publications
The SUMER spectral atlas of solar-disk features
Dwivedi, B. N.; Wilhelm, K.; Curdt, W. +4 more
A far-ultraviolet and extreme-ultraviolet (FUV, EUV) spectral atlas of the Sun between 670 Å and 1609 Å in the first order of diffraction has been derived from observations obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory). The atlas contains spect…
On the nature of the transition region from the chromosphere to the corona of the Sun
Peter, H.
One of the keys to understand coronal heating is to understand the (magnetic) structure of the atmosphere below the respective coronal features. The EUV emission lines formed in the thin transition region from the chromosphere to the corona present a sensitive tool to study the structure and dynamics of the lowermost corona and its connection to t…
Slow magnetoacoustic waves in coronal loops: EIT and TRACE
Berghmans, D.; Poedts, S.; Hochedez, J. F. +3 more
On May 13, 1998 the EIT (Extreme ultraviolet Imaging Telescope) on board of SoHO (Solar and Heliospheric Observatory) and TRACE (Transition Region And Coronal Explorer) instruments produced simultaneous high cadence image sequences of the same active region (AR 8218). TRACE achieved a 25 s cadence in the Fe Ix (171 Å) bandpass while EIT achieved a…
Prominence fine structures in a magnetic equilibrium: Two-dimensional models with multilevel radiative transfer
Heinzel, P.; Anzer, U.
In this paper we construct theoretical models for vertical prominence threads which are in magnetohydrostatic (MHS) equilibrium. These models are fully two-dimensional (2D) and take the form of vertically infinite threads hanging in a horizontal magnetic field. A typical example of such a 2D magnetic-dip structure is shown for the case when the ce…
Transition region oscillations above sunspots
Fludra, A.
We present observations of three sunspots made in the EUV wavelength range with the Coronal Diagnostic Spectrometer (CDS) on SOHO. We examine time series of line intensities obtained with a 15-s cadence and calculate their Fourier power spectra and the wavelet transforms. We find oscillations in the chromosphere and transition region above sunspot…
Active region transient brightenings. A simultaneous view by SXT, EIT and TRACE
Berghmans, D.; Clette, F.; McKenzie, D.
This paper reports on a qualitative study on the weakest flarelike brightenings in active region that can be observed with current coronal imagers. Specificallly, we investigate the correspondence of the ``active region transient brightenings'' (ARTB) first observed almost a decade ago with SXT with similar brightenings in the EUV that are now obs…
The nature of network oscillations
Doyle, J. G.; Banerjee, D.; O'Shea, E. +1 more
We examine time-series of spectral data obtained from the Coronal Diagnostic Spectrometer (CDS) and the Solar Ultraviolet Measurements of Emitted Radiation instrument (SUMER) onboard the Solar Heliospheric Observatory (SOHO) spacecraft, in the period 30-31 July 1996. The observations were obtained in lines, ranging in temperature from 12 000 K to …
Analysis of blinkers and EUV brightenings in the quiet Sun observed with CDS
Solanki, S. K.; Brković, A.; Rüedi, I.
Movies of quiet Sun regions at disc centre obtained with the Coronal Diagnostic Spectrometer (CDS) onboard the SOHO spacecraft are used to study the properties of transient brightenings seen in the extreme ultraviolet (EUV), so-called blinkers, at three different temperatures sampled simultaneously in the chromospheric He I 584.3 Å (2 x 104
Interpretation of coronal off-limb spectral line width measurements
Moran, T. G.
Spectral line widths measured above the solar limb have been used to infer wave velocity amplitude height dependencies, supporting Alfven wave coronal heating and wave driven solar wind models. Comparison of the inferred amplitude/density dependence with a constant magnetic field strength, undamped wave propagation model have shown good agreement,…
SOHO/SUMER observations and analysis of the hydrogen Lyman spectrum in solar prominences
Heinzel, P.; Vial, J. -C.; Schmieder, B. +1 more
The complete hydrogen Lyman spectrum in several prominences has been observed with the UV spectrometer SUMER on-board the SOHO, during the Joint Observing Programme 107, together with other space and ground-based observatories. Based on these observations, we are able to demonstrate, for the first time, that there exists a large variety of intensi…