Imaging Prominence Eruptions Out to 1 AU

TL;DR

This paper presents the observation and analysis of two prominence eruptions tracked from the Sun to 1 AU using STEREO spacecraft, revealing insights into their structure, dynamics, and expansion behavior.

Contribution

It provides the first detailed 3-D reconstruction of a prominence eruption out to 1 AU and develops a mathematical framework for analyzing their self-similar expansion.

Findings

Prominences can be observed persistently bright out to 1 AU.

The 2011 June prominence showed little deceleration, moving within the CME.

Prominence expansion is close to self-similar, with slight deviations near the Sun.

Abstract

Views of two bright prominence eruptions trackable all the way to 1AU are here presented, using the heliospheric imagers on the Solar TErrestrial RElations Observatory (STEREO) spacecraft. The two events first erupted from the Sun on 2011 June 7 and 2012 August 31, respectively. Only these two examples of clear prominence eruptions observable this far from the Sun could be found in the STEREO image database, emphasizing the rarity of prominence eruptions this persistently bright. For the 2011 June event, a time-dependent 3-D reconstruction of the prominence structure is made using point-by-point triangulation. This is not possible for the August event due to a poor viewing geometry. Unlike the coronal mass ejection (CME) that accompanies it, the 2011 June prominence exhibits little deceleration from the Sun to 1 AU, as a consequence moving upwards within the CME. This demonstrates that prominences are not necessarily tied to the CME's magnetic structure far from the Sun. A mathematical framework is developed for describing the degree of self-similarity for the prominence's expansion away from the Sun. This analysis suggests only modest deviations from self-similar expansion, but close to the Sun the prominence expands radially somewhat more rapidly than self-similarity would predict.