Automated LASCO CME catalog for solar cycle 23: are CMEs scale invariant?

TL;DR

This study introduces an automated CME catalog from LASCO data, revealing scale-invariant CME widths and consistent CME rates over solar cycle 23, highlighting the turbulent nature of the solar corona.

Contribution

First automated LASCO CME catalog created using CACTus, showing CME width scale invariance and consistent rates, with implications for understanding CME size distribution.

Findings

CME width distribution is scale invariant from 20 to 120 degrees.

CME rates are consistent with historical data after correction.

Small-scale outflows are ubiquitous and related to turbulence.

Abstract

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