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Proper Motions of Coronal Bright Points

Full-field full-resolution solar images obtained by the Extreme Ultraviolet Imaging Telescope on board the Solar and Heliospheric Observatory are used to analyse proper motions, velocity distributions, lifetimes, and diffusion coefficient of coronal bright points. The results obtained by the interactive method for three tracer subtypes (point-like structures, small loops, and small active regions) of coronal bright points for the period 4 June 1998 to 22 May 1999 are presented and compared. Distributions of meridional velocities, residual azimuthal velocities and velocities of proper motions are presented for the three tracer subtypes. Lifetimes up to 54 hours are found for 98% of all observed coronal bright points. Small active regions last on the average longer than point-like structures and small loops. The correlation between the absolute velocity of proper motion and lifetime is investigated and the mean free path (in the range from 3000 km to 15000 km) and the diffusion coefficient (approximately 200 km2/s) of coronal bright points are estimated. Finally, characteristics of the random walk process associated to the motions of coronal bright points are discussed in the Appendix.

solar rotation ; coronal bright points ; SOHO-EIT

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