How the Sun transfers energy into its upper atmosphere

The Sun
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An international team of researchers have shed light on one of the mysteries of solar physics: how energy from the Sun is transferred to the star’s upper atmosphere.

The international team of scientists have set out to discover of the Sun can heat its upper atmosphere to 1m degrees Fahrenheit, which is considerably hotter than the Sun’s surface.

Using new images from New Jersey Institute of Technology’s (NJIT) Big Bear Solar Observatory (BBSO), the research team has revealed in granular detail what appears to be a likely mechanism. The mechanism consists of jets of magnetised plasma known as spicules that spurt like geysers from the Sun’s upper atmosphere into the corona.

The team wrote a paper published in Science, in said paper the team describes key features of jet-like spicules that are in solar terms small scale plasma structure, measuring between 200 and 500 kilometres wide. The structures continuously erupt across the Sun’s expanse.

The researchers have for the first time shown where and how the jets are generated and the paths they travel, at speeds of around 100 kilometres per second in some cases, into the corona.

Solar Physicist Wenda Cao, BBSO’s director and one of the authors from this paper, said: “Unprecedented high-resolution observations from BBSO’s Goode Solar Telescope clearly show that when magnetic fields with opposite polarities reconnect in the Sun’s lower atmosphere these jets of plasma are powerfully ejected,

“This is the first time we’ve seen direct evidence of how spicules are generated. We have tracked these dynamic features in the H-alpha spectral line down to their foot points, measured the magnetic fields at their foot point, captured the migration of the emerging magnetic elements and verified their interaction with existing magnetic fields of the opposite polarity.”

The images captured in the extreme ultraviolet (EUV) spectrum by NASA’s Solar Dynamics Observatory spacecraft were used to track the transportation of energy in the corona. These observations showed that it is also common for spicules to be heated to typical coronal temperatures.

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