Statistical study of the origin and 3D acceleration profile of small solar wind tracers (blobs)
Abstract
Blobs are small density enhancements observed in the solar corona (Sheeley et al. 1997). The study of blob propagation is important because they are considered to be tracers of the slow component of the solar wind. To explore the physical mechanisms behind the propagation of the slow solar wind, we have studied the kinematics of blobs embedded in the continuously expanding solar corona along the years 2007 to 2008, i.e., during the extended past solar minimum. The scarce presence of CMEs events during the selected periods of observation, has permitted the identification of around 100 blob-like structures on the LASCO and SECCHI coronagraphs on board SOHO and STEREO missions, respectively. This allowed us to estimate their un-projected trajectories between 2 and 15 solar radii, using the Height-Time technique (Mierla et al., 2008). In agreement with the idea that blobs are liberated from the cusps of helmet steamers (Wang et al., 1998) and considering their latitudinal distribution during the selected periods of observation, we constrained the observing region of interest in the coronagraphs field of view to ≤30° from the Sun's equator. We inferred their location in the close solar corona by the tridimensional Potential Field Source Surface (PFSS) developed by De Rosa (2003) and implemented in the FORWARD package (people.hao.ucar.edu/sgibson/FORWARD/). Our results support previous findings that track down the origin of the slow solar wind to neighboring regions of helmet streamers and pseudostreamers (Wiegelmann et al., 1998, Wang et al., 2012).
- Publication:
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Solar Heliospheric and INterplanetary Environment (SHINE 2014)
- Pub Date:
- June 2014
- Bibcode:
- 2014shin.confE..44L