Tracking Streamer Blobs Into the Heliosphere

TL;DR

This study tracks streamer blobs from the solar corona into the heliosphere using STEREO images, revealing their spiral structure and interactions with solar wind, and identifying a visibility locus that explains observed asymmetries.

Contribution

It introduces a detailed analysis of streamer blob trajectories and the identification of a 'locus of enhanced visibility' that clarifies their observational signatures.

Findings

Discovered a 'locus of enhanced visibility' for streamer blobs.

Revealed the spiral structure of blobs in the heliosphere.

Tracked large-scale waves back to their coronal origins.

Abstract

In this paper, we use coronal and heliospheric images from the STEREO spacecraft to track streamer blobs into the heliosphere and to observe them being swept up and compressed by the fast wind from low-latitude coronal holes. From an analysis of their elongation/time tracks, we discover a 'locus of enhanced visibility' where neighboring blobs pass each other along the line of sight and their corotating spiral is seen edge on. The detailed shape of this locus accounts for a variety of east-west asymmetries and allows us to recognize the spiral of blobs by its signatures in the STEREO images: In the eastern view from STEREO-A, the leading edge of the spiral is visible as a moving wavefront where foreground ejections overtake background ejections against the sky and then fade. In the western view from STEREO-B, the leading edge is only visible close to the Sun-spacecraft line where the radial path of ejections nearly coincides with the line of sight. In this case, we can track large-scale waves continuously back to the lower corona and see that they originate as face-on blobs.