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Gas flows in the transition region above sunspots

DOI

56

Citations

0

References

1988

Year

O. Kjeldseth‐Moe, N. Brynildsen, P. Brekke, O. Engvold, P. Maltby, J. D. F. Bartoe, G. E. Brueckner, J. W. Cook, K. P. Dere, D. G. Socker
The Astrophysical Journal

Abstract

Strong downflows and moderate upflows in the transition region over a sunspot have been observed with the HRTS on Spacelab 2 in 1985. The flows are persistent in the sense that they are seen in the same spot for 5 days. The downflows are prominent in regions of limited extent (4arcsec - 6arcsec), and flow velocities are in the range 40 - 80 km s<SUP>-1</SUP> and are thus supersonic. Upward flows have smaller velocities, 5 - 20 km s<SUP>-1</SUP>, but may extend over a larger area. In the downflowing regions there is always an appreciable amount of gas at rest in the line of sight. Flow speeds derived from the profiles of different lines formed in the transition region between 30,000 and 230,000K are very similar implying constant downflow in this temperature range.