Multi-wavelength study of the slow "disparition brusque" of a filament observed with SOHO

A mid-latitude filament was observed before and after its eruption with SOH O (EIT, SUMER, CDS and LASCO) and with ground based observatories (Meudon a nd Pic du Midi) in the context of a coordinated MEDOC campaign in Orsay. Th e eruption was followed by a large Coronal Mass Ejection well observed by L ASCO. Few hours before its eruption, the filament is partially heated las s een in 195 Angstrom with EIT). The physical conditions of the filament befo re its eruption have been investigated by spectroscopic analysis of SUMER ( the Lyman series L4 to L9) and of CDS combined with the Multi-channel Subtr active Double Pass Spectrograph (MSDP) spectra of H alpha. Five hours befor e the eruption, large broadenings of chromospheric and transition region li nes (CDS) were observed in the main body of the filament suggesting strong turbulence as well as opposite Dopplershifts on each side of the filament ( H alpha and He I) which could be interpreted as twist motions. The optical thickness of the filament is rather large. During the eruption the twist is largely developed as observed in 304 Angstrom. The Doppler shifts of the f ilament estimated from Lyman lines are in good agreement with the velocity of the front edge of the CME bright loop. We notice that both, the filament and the bright loop, are deviated towards the equator. This implies that t hey belong to the same global expansion event constrained to remain in the equatorial streamer. An X-ray bright point observed close to a filament foo tpoint could be the signature of reconnection process linked to the destabi lization of the filament. It is interpreted in the framework of new MHD mod eling of lateral filament footpoints (Aulanier & Demoulin 1998).