What makes up the Sun’s coronal heat losses?
doi:10.1038/nindia.2018.131 Published online 14 October 2018
The Sun’s corona, or outer atmosphere, continuously loses heat into outer space. Despite such heat loss, the corona maintains a high temperature.
Energy-carrying pseudo-shocks, formed locally in the Sun’s atmosphere, heat up the corona, compensating for its heat loss, reveals a study1. This will help in understanding various other similar astrophysical plasma sources such as other Sun-like magnetised, young and active stars.
Besides happening on a global scale, energy and mass transport in the Sun’s atmosphere may occur locally through the formation of shocks, waves and flows.
To shed light on how such local events shape the Sun’s energy output, an international team including physicists from the Indian Institute of Technology, Banaras Hindu University in Varanasi, India, has mapped a region around a sunspot, areas where the magnetic field is about 2,500 times as strong as those of the Earth’s.
They identified a number of pseudo-shocks that contain ions and neutral particles. The ions and neutral particles collide with one another as the shocks propagate through the Sun’s atmosphere. The pseudo-shocks, lasting 150 seconds, possibly lose energy and fade gradually after reaching the inner corona.
Born abundantly in and around sunspots, the pseudo-shocks carry sufficient amounts of energy to possibly balance the localised coronal heat losses above the sun’s active regions. The researchers say that the pseudo-shocks, discovered as a new energy source in the solar atmosphere, may also act as a ready reference for the laboratory-based plasma as well as fluid-dynamics experiments.
1. Srivastava, A. K. et al. Confined pseudo-shocks as an energy source for the active solar corona. Nat. Astron. (2018) doi: 10.1038/s41550-018-0590-1