Flare productivity of newly-emerged paired and isolated solar active regions

Dalla, S., Fletcher, L. and Walton, N.A. (2007) Flare productivity of newly-emerged paired and isolated solar active regions. Astronomy and Astrophysics, 468(3), pp. 1103-1108. (doi: 10.1051/0004-6361:20077177)

Abstract

<p><b>Aims:</b> We investigate whether sunspot regions that emerge near existing ones are more flare productive than those that emerge isolated.</p> <p><b>Methods:</b> We analyse a sample of 2115 new regions obtained from the USAF/Mount Wilson catalogue of sunspot regions. For our analysis we use AstroGrid, a Virtual Observatory developed in the UK, to build a series of workflows that perform queries to catalogues of solar regions and flares, and operations on the results of the queries. If a new region emerged through the solar surface within 12 of a pre-existing one, we classify it as paired, otherwise as isolated.</p> <p><b>Results:</b> We find that paired regions are more flare productive than isolated ones, although this is a small effect. Here only soft X-ray flares of magnitude greater than C1.0 are considered, and flare productivity is characterised by the percentage of regions that produced at least one flare over 4 days since emergence, and by the average number of flares over the same period. For paired regions, we also consider the flare productivity of the nearby companion region and find that if a flare does happen within the pair, it will more likely take place in the companion region than in the newly-emerged one. Our results show that although emergence in proximity to another region can slightly increase the probability of a flare taking place, presumably by increasing the likelihood of magnetic reconnection and significant change in magnetic topology, this is not a large effect. It appears that intrinsic properties of the region are the key factor in determining whether or not it will produce flares, as opposed to interaction with pre-existing regions.</p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fletcher, Professor Lyndsay
• Authors: Dalla, S., Fletcher, L., and Walton, N.A.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Astronomy and Astrophysics
• Publisher: EDP Sciences
• ISSN: 0004-6361
• ISSN (Online): 1432-0746
• Copyright Holders: Copyright © 2007 EDP Sciences
• First Published: First published in Astronomy and Astrophysics 468(3):1103-1108
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher