AUTOMATED LASCO CME CATALOG FOR SOLAR CYCLE 23: ARE CMEs SCALE INVARIANT?

Abstract

In this paper we present the first automatically constructed LASCO CME\ncatalog, a result of the application of the Computer Aided CME Tracking\nsoftware (CACTus) on the LASCO archive during the interval September 1997 -\nJanuary 2007. We have studied the CME characteristics and have compared them\nwith similar results obtained by manual detection (CDAW CME catalog). On\naverage CACTus detects less than 2 events per day during solar minimum up to 8\nevents during maximum, nearly half of them being narrow (< 20 degrees).\nAssuming a correction factor, we find that the CACTus CME rate is surprisingly\nconsistent with CME rates found during the past 30 years. The CACTus statistics\nshow that small scale outflow is ubiquitously observed in the outer corona. The\nmajority of CACTus-only events are narrow transients related to previous CME\nactivity or to intensity variations in the slow solar wind, reflecting its\nturbulent nature. A significant fraction (about 15%) of CACTus-{\\it only}\nevents were identified as independent events, thus not related to other CME\nactivity. The CACTus CME width distribution is essentially scale invariant in\nangular span over a range of scales from 20 to 120 degrees while previous\ncatalogues present a broad maximum around 30 degrees. The possibility that the\nsize of coronal mass outflows follow a power law distribution could indicate\nthat no typical CME size exists, i.e. that the narrow transients are not\ndifferent from the larger well-defined CMEs.\n