The Wide-field Imager for Parker Solar Probe (WISPR) Science Team, led by the U.S. Naval Research Laboratory (NRL), captured the development of turbulence as a Coronal Mass Ejection (CME) interacted with the ambient solar wind in the circumsolar space. This discovery is reported in the Astrophysical Journal. Taking advantage of its unique location inside the sun's atmosphere, the NRL-built WISPR telescope on NASA's Parker Solar Probe (PSP) mission, operated by the Johns Hopkins University Applied Physics Laboratory (JHUAPL), captured in unparalleled detail the interaction between a CME and the background ambient solar wind. To the surprise of the WISPR team, images from one of the telescopes showed what seemed like turbulent eddies, so-called Kelvin-Helmholtz instabilities (KHI). Such structures have been imaged in the terrestrial atmosphere as trains of crescent wave-like clouds and are the results of strong wind shear between the upper and lower levels of the cloud. This phenomenon, while rarely imaged, is thought to occur regularly at the interface of fluid flows when the right conditions arise. "We never anticipated that KHI structures could develop to large enough scales to be imaged in visible light CME images in the heliosphere when we designed the instrument," said Angelos Vourlidas, Ph.D., JHUAPL and WISPR Project Scientist. "These fine detail observations show the power of the WISPR high sensitivity detector combined with the close-up vantage point afforded by Parker Solar Probe's unique sun-encounter orbit," said Mark Linton, Ph.D., head of NRL Heliophysics Theory and Modeling Section and Principal Investigator for the WISPR instrument. The keen eye of an early career member of the WISPR team, Evangelos Paouris, Ph.D., George Mason University detected the KHI structures. Paouris and his WISPR colleagues undertook a thorough investigation to verify that the structures were indeed KHI waves. The results not only report an... |