The observations took place during Parker Solar Probe's eighth encounter with the sun. "With Parker Solar Probe now flying into the magnetically-dominated corona, we will get the long-awaited insights into the inner workings of this mysterious region." Raouafi, the Parker Solar Probe Project Scientist at JHU/APL. Still, we cannot tell precisely what that physics is," said Nour E. "We have been observing the sun and its corona for decades, and we know there is interesting physics going on there to heat and accelerate the solar wind plasma. The probe also recorded some evidence of a potential power boost just inside the corona, which may point to unknown physics affecting heating and dissipation. Alternatively, low rates of magnetic reconnection on the sun's surface could have pumped less mass into the observed wind stream, resulting in fewer switchbacks. ![]() The finding could mean that switchbacks do not form within the corona. Researchers noticed far fewer switchbacks below the Alfvén critical surface than above it. It is not currently known why a pseudostreamer would push the Alfvén critical surface away from the sun. The data suggest that the largest and most distant wrinkle of the surface was produced by a pseudostreamer - a large magnetic structure more than 40 degrees across, found back on the innermost visible face of the sun. Surprisingly, the researchers discovered that the Alfvén critical surface is wrinkled. This is the first time a spacecraft has entered the solar corona and touched the atmosphere of the sun. The spacecraft passed above and below the surface three separate times during its encounter. Below that surface, the pressure and energy of the sun's magnetic field was stronger than the pressure and energy of the particles. This past April, the probe spent five hours below the Alfvén critical surface in direct contact with the sun's plasma. In 2018, NASA launched Parker Solar Probe with the goal of finally reaching the sun's corona and making humanity's first visit to a star. "The concept of sending spacecraft into the magnetized atmosphere of the sun - sufficiently close that the magnetic energy is greater than both ion and electron kinetic and thermal energy - predated NASA itself," said Kasper. ![]() Many scientists think that sudden reverses in the sun's magnetic field, called switchbacks, emerge from this area. The sun's outer edge begins at the Alfvén critical surface: the point below which the sun and its gravitational and magnetic forces directly control the solar wind. The probe made the first direct observations of what lies within the sun's atmosphere, measuring phenomena previously only estimated. The mission is led by the Johns Hopkins University Applied Physics Laboratory (JHU/APL). Kasper, the first author, Deputy Chief Technology Officer at BWX Technologies, and a professor at the University of Michigan. "This marks the achievement of the primary objective of the Parker mission and a new era for understanding the physics of the corona," said Justin C.
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