Astron. Astrophys. 360, 351-362 (2000)

Solar spicules and macrospicules observed by SUMER

K. Wilhelm

Max-Planck-Institut für Aeronomie, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany (Wilhelm@linmpi.mpg. de)

Received 11 April 2000 / Accepted 6 June 2000

Abstract

Motivated by recent observations of spicules and macrospicules in the far-ultraviolet (FUV) wavelength range with the Solar Ultraviolet Measurements of Emitted Radiation spectrograph (SUMER) on the Solar and Heliospheric Observatory (SOHO), a generation mechanism for spicules and macrospicules is outlined which deviates significantly from most of the previous concepts. The important aspect is that the spicule propagation is not strictly aligned along the local magnetic field direction and that there is a close association with explosive events. It is suggested that the chromospheric material will be carried up by the relaxing magnetic field following a field line reconnection. Some of the consequences for spicules and other features of the quiet-Sun (QS) atmosphere will be discussed, such as the average red shift of FUV emission lines in the transition region (TR) and polar plume formation in coronal holes (CHs).

Key words: Sun: chromosphere Sun: corona Sun: magnetic fields Sun: transition region Sun: UV radiation

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. Observations of spicules and macrospicules in the FUV
• 3. Outline of a spicule mechanism
• 4. Discussion
  • 4.1. Expansion perpendicular to propagation direction
  • 4.2. The average red shift of FUV lines
  • 4.3. Succession of loops in the low-latitude corona
  • 4.4. Height of loop apex in CHs
  • 4.5. Plumes in CHs
• 5. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: July 27, 2000
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