Purpose of the Meeting

Plasma jets could be a prototype of the most important fundamental phenomena in plasma physics and MHD; they are often associated with magnetic energy dissipation and propagation processes and play a role in mass and momentum transfer; therefore they are of general interest.

- The solar atmosphere is full of dynamical events. In particular, jet-like phenomena such as spicules and surges observed in H alpha, He D3 and other lines, eclipse white light coronal spikes (S-prominences), TR events, EUV jets and transient brightenings, explosive events and turbulent events have been reported frequently in the literature.

- It has often been suggested that these jet-like phenomena might play an important role in chromospheric/coronal heating, and might accelerate as well as supply mass to the corona and/or the high speed solar wind. However, it is not yet clear how these MHD jet-like features are related to both the atmospheric heating and the acceleration of the solar wind.

- Recent progress in spaceborne solar physics has revitalized research in solar jets and plumes. Yohkoh SXT discovered a new class of jets, X-ray coronal jets from microflares and in the faintest case, for example in a coronal hole, even from nanoflares. Several SOHO experiments have jointly observed in much details polar plumes, while high spatial resolution micro and radio waves observations have revealed similar jet and plume like structures. It has also been found that if we observe the corona with longer exposure time, the number of observed X-ray jets increases. From these observations, the conjecture has emerged that all microflares/nanoflares might be accompanied by jets.

- Solar jet phenomena could be the prototype of cosmic jet phenomena, such as radio jets ejected from active galactic nuclei. In these cosmic jets, the role of the magnetic field has not yet been firmly established; accordingly, the study of solar jet phenomena can also contribute to research on cosmic jets, providing many examples of collimation and acceleration of plasmas by the magnetic field.

- Polar plumes are different from jets in that they appear to be much more permanent structures, but they are similar in being elongated and of magnetic origin. Plumes have been observed in white light during eclipses and by LASCO, in emission lines by the SUMER and CDS spectrometers on SOHO, in UV by SOHO/EIT and UVCS, and occasionally in soft X-rays by Yohkoh-SXT. The material in plumes appears to be cooler and denser than the surrounding corona, and moving outwards slowly. Research on the magneto-hydrodynamic (MHD) structure of plumes has only barely begun, and it is the feeling of the organizers that a close comparison with the MHD of jets, which is much better known, may be beneficial to both fields.

The proposed meeting is the first international meeting exclusively concentrated on solar jets and plumes. The organizers feel the time is ripe to measure the progress in the field and produce a comprehensive review of the study of solar and cosmic jet and plume phenomena. Since a total eclipse is such a rare occasion to study small scale coronal jets and plumes, the meeting will be held during the week of the total solar eclipse in Guadeloupe (France) and hence the dates of the meeting will be Feb. 22 to 26, 1998 (firm dates!).