The fine structure of prominences

Faint, Doppler shifted, emission features are detected in high resolution spectra of limb prominences. Their average line-of-sight velocity is about 3 × 10⁶ cm s^-1, their average life time is 300 s, and their angular sizes are 10⁸ cm in our spectrograms. The emission line width of the spectral features increases with increasing line shift.Some implications on the stability of prominences by these structures are discussed briefly.Visiting Astronomer, on leave from the Department of Astro-Geophysics, University of Colorado, Boulder, Colorado.