Details

Autor(en) / Beteiligte

• Brynildsen, N
• Brekke, P
• Fredvik, T
• Haugan, SVH
• Kjeldseth-Moe, O
• Maltby, P
• Harrison, R A
• Wilhelm, K

Titel

Soho Observations of the Connection Between Line Profile Parameters in Active and Quiet Regions and the Net Red Shift in Euv Emission Lines

Ist Teil von

• Solar physics, 1998-07, Vol.181 (1), p.23-50

Ort / Verlag

Dordrecht: Springer Nature B.V

Erscheinungsjahr

1998

Link zum Volltext

Quelle

Springer LINK 全文期刊数据库

Beschreibungen/Notizen

• We present high spatial and spectral resolution observations of one active and one quiet-Sun region, obtained with CDS and SUMER on SOHO. The connections between the line profile parameters are studied and a systematic wavelength shift towards the red with increasing peak line intensity (line broadening) is detected. The large scatter in the data calls for another approach. We apply conditional probability analysis to a series of EUV emission lines and find significant correlations between line profile parameters. For a given interval in wavelength shift we find that: (1) line profiles with large intensities (line widths) and red shifts above the average constitute an increasing fraction of the profiles as the relative wavelength shift increases, (2) line profiles with large intensities (line widths) and blue shifts compared to the average, on the other hand, constitute a decreasing fraction of the profiles as the relative wavelength shift increases. These results extend the findings of an earlier quiet-Sun study from one to several emission lines and expand the validity to include the active region. Interestingly, the active region observations show correlations between peak line intensity and wavelength shift in the coronal lines. The tendency for red-shifted profiles to be more intense than blue-shifted profiles will shift line profiles derived by integrating along the slit towards the red. From the present observations we are not able to determine the fraction of the net red shift that emerges from this correlation. We suggest that the same mechanism is responsible both for the correlation between the line profile parameters and for the differential red shift between the transition region and chromospheric emission lines.