To uncover the origins of stealth CMEs, the scientists developed a model of the Sun’s magnetic fields, simulating their strength and movement in the Sun’s atmosphere. Central to the model was the Sun’s differential rotation, meaning different points on the Sun rotate at different speeds. Unlike Earth, which rotates as a solid body, the Sun rotates faster at the equator than it does at its poles.
The model showed that this differential rotation causes the Sun’s magnetic fields to stretch and spread at different rates. The scientists demonstrated this constant process generates enough energy to form stealth CMEs over the course of roughly two weeks. The Sun’s rotation increasingly stresses magnetic field lines over time, eventually warping them into a strained coil of energy. When enough tension builds, the coil expands and pinches off into a massive bubble of twisted magnetic fields, and without warning, the stealth CME quietly leaves the Sun.
Compared to typical CMEs, which erupt from the Sun as fast as 2900 km/s (1800 miles per second), stealth CMEs move at a ‘rambling gait’ — between 400 and 700 km/s (250 to 435 miles per second). That’s roughly the speed of the more common solar wind, the constant stream of charged particles that flows from the Sun.
Due to their speed, stealth CMEs aren’t typically powerful enough to drive major space weather events, but they can still cause minor to moderate disturbances to Earth’s magnetic field because of their internal magnetic structure. Such computer models can help researchers better understand how the Sun affects near-Earth space, and potentially improve our ability to predict space weather.
Source Reference: https://watchers.news/2017/05/10/model-explains-the-formation-of-stealth-cmes/
Credit for Image at Top of Page: NASA’s Goddard Space Flight Center