National Aeronautics and Space Administration

Living With A Star

Targeted Research and Technology

Helicity-driven sigmoid evolution and its role in CME initiation

ROSES ID: NRA-02-OSS-01      Selection Year: 2003      

Program Element: Independent Investigation: LWS

Principal Investigator: David Alexander

Affiliation(s): Lockheed Martin Solar and Astrophysics Laboratory

Project Member(s):
Nightingale, Richard W COI Lockheed Martin Advanced Techlgy Ctr
Shine, R A COI Lockheed Palo Alto Research Labs
Metcalf, Tom Collaborator LMSAL


Recent observations of rotating sunspots in TRACE white light images and their apparent association with soft X-ray sigmoids have led to the intriguing possibility that observations of sunspot rotation serve to identify the driver for sigmoid formation, evolution and their potential eruption. A number of rotating sunspot events have now been observed, many associated with some of the largest solar flares and CMEs of this solar cycle. We propose to explore the energization of the corona resulting from the observed rotational motions of the sunspots. In particular we will focus on the relationship between the sunspot rotation and the evolution of sigmoid structures with the objective to determine the key physical conditions that govern whether a sigmoid will destabilize and produce a CME. The role of the coronal helicity injection implicit in the sunspot rotation will be explored as the ~proximate cause for the sigmoid evolution. This study will lead to a better understanding of the physics that determines the conditions for sigmoid eruption and, consequently, may lead to a useful forecasting tool for predicting geo-effective events.


Performance YearReferenceInvestigation TypeActions
1Alexander, David   Rice U. - Helicity-driven sigmoid evolut...
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