In a joint international study led by scientists from India and the UK, researchers have deciphered the physics behind solar plasma jets through computer simulation and lab experiments. Solar plasma jets, or spicules, are powerful plasma streams constantly ejecting from the Sun’s chromosphere (an atmospheric layer above the Sun’s visible surface). These jets rise and fall back under the influence of the Sun’s gravity, which is 20 to 30 times greater than Earth. Some jets are so energetic that they propel into the solar corona and beyond.
To understand the physics triggering the plasma jet, the study led by researchers at the Indian Institute of Astrophysics (IIA), Bengaluru, performed laboratory experiments and simulations. In one such experiment, the scientists observed how paint placed over bass audio speakers ejected as a forest of jets when a certain sound frequency and amplitude (speaker’s loudness) were surpassed.
“We were surprised to find that the underlying physics of the paint jets and that of the solar plasma jets are analogous,” said Piyali Chatterjee, IIA scientist and co-author of the latest study published in the journal Nature Physics. The four key ingredients favouring solar jets, according to Chatterjee, are the plasma’s fluid nature, gravity, strong quasi-periodic triggers to eject the plasma and most importantly, the Sun’s powerful magnetic field giving it a specific direction for ejection.
As already established, the Sun’s surface is constantly in the state of convection powered by the energy obtained from the Sun’s dense core. The convection provides strong periodic kicks enabling the plasma to eject as jet streams.
