Filaments disappearances in relation to solar ﬂares during the solar cycle 23 R. Mawad a,d,⇑ , Mosalam Shaltout b , M. Ewaida c , M. Yousef d , S. Yousef e a Astronomy & Meteorology Department, Faculty of Science, Al-Azhar University, Egypt b National Research Institute of Astronomy and Geophysics, Helwan, Egypt c Physics Department, Faculty of Science, Menoﬁa University, Egypt d Space Weather Monitoring Center, Physics Department, Helwan University, Egypt e Astronomy Department, Cairo University, Faculty of Science, Egypt Received 1 April 2014; received in revised form 4 October 2014; accepted 4 November 2014 Available online 13 November 2014 Abstract We studied the association between the ﬁlament disappearances and solar ﬂares during 1996–2010; we listed 639 associated ﬁlament disappearances with solar ﬂares under temporal and spatial condition, those particular 639 ﬁlament disappearance were associated with 1676 solar ﬂares during the period 1996–2010. The best angular distance between ﬁlament disappearances and associated solar ﬂares ranged between 30° and 60°. The number of the associated events increased with increasing solar activity and decreased with quiet sun. The location of ﬁlament disappearances ranges between latitude ±50° and longitude ±70°. We found that longer ﬁlament disappearances have activity and ability of contemporary association with ﬂares more than shorter ﬁlament disappearance, ﬁlament disappearance powers the associated ﬂares more than non-associated ﬂares events. The associated ﬂares have higher solar ﬂux, longer duration, and higher importance compared to non-associated ﬂares with ﬁlament disappearance. In addition the associated ﬁlament disappearance with ﬂares have two types depending on their duration, short-lived (<9 h), and long-lived (>9 h). Ó 2014 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Filament; Filament disappearance; Solar ﬂare 1. Introduction A review of ﬁlament disappearance relationship which is given by Smith and Ramsey (1964) extracts from this review is given below: Newton (1934) recognized 2 types of ﬂare associated ﬁlament disappearances: (1) ﬁlament disappearances asso- ciated with sunspot groups, (2) ﬁlament disappearances not associated with sunspot groups. Newton (1935) also reported cases of ﬁlaments exhibiting high radial velocities and complete or partial disappearances after ﬂare start. In a study of ﬂares observed during the period from March to December 1988, Giovanelli (1940) found that approxi- mately one ﬁfth of the ﬂares gave rise to eruptive promi- nences (ﬁlaments), and that there is a statistical increase in the velocity of the ejected prominence with an increase in the intensity of the ﬂare. A more complete description of ﬂare-associated ﬁlament motions was published by Newton (1942). Bruzek (1951, 1958) noted events in which strengthening of a ﬁlament, combined with ascending motion, occurred before the start of a ﬂare and prior to the dissolution of the ﬁlament. Martres (1956) pointed out that for disparitions brusques (sudden ﬁlament http://dx.doi.org/10.1016/j.asr.2014.11.003 0273-1177/Ó 2014 COSPAR. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Astronomy & Meteorology Department, Faculty of Science, Al-Azhar University, Egypt. E-mail addresses: ramy@azhar.edu.eg (R. Mawad), mosalam_shaltout@ yahoo.com (M. Shaltout), myousef7174@gmail.com (M. Yousef), mostafa. shahinaz@yahoo.com (S. Yousef). www.elsevier.com/locate/asr Available online at www.sciencedirect.com ScienceDirect Advances in Space Research 55 (2015) 696–704