The Science behind jets of plasma occurring all over Sun’s chromosphere

• Scientists have unraveled the science behind the jets of plasma - 4th state of matter consisting of electrically charged particles, occur everywhere in the sun’s chromosphere.

Plasma Jets

• These jets or spicules appear as thin grass-like plasma structures that constantly shoot up from the surface and are then brought down by gravity.
• The amount of energy and momentum that these spicules can carry is of fundamental interest in solar and plasma astrophysics.
• Spicules come in all sizes and speeds.
• The physics behind the short spicules is different from that of taller and faster spicules.

The Chromosphere

• Just above the photosphere is the chromosphere.
• It is relatively a thin layer of burning gases.
• The chromosphere is a bit cooler - 4,320 ֯C.
• The chromosphere is 500 times lighter than the plasma in the photosphere.

The Science of Plasma

• The plasma right below the visible solar surface (photosphere) is perpetually in a state of convection, much like boiling water in a vessel heated at the bottom.
• It is ultimately powered by the nuclear energy released in the hot-dense core.
• The convection serves almost periodic but strong kicks to the plasma in the solar chromosphere(a shallow semi-transparent layer right above the visible solar disk).

The Study

• To explore the underlying physics of spicule dynamics, the team turned to an audio speaker.
• A bass speaker responds to excitation at low frequencies like the rumbling sounds heard in movies.
• When a liquid is placed above such a speaker and the music is turned on, the free surface of the liquid becomes unstable beyond a particular frequency and starts vibrating.
• A fluid like paint or shampoo will result in unbroken jets when excited on a speaker since its long polymer chains give it directionality.
• The scientists realized that the physics underlying these paint jets must be analogous to the solar plasma jets.
• The solar plasma can be imagined as threaded by magnetic field lines, much like the long chains in polymer solutions.
• The study challenges this widespread belief to show that solar convection can by itself form all kinds of jets - short as well as tall.
• The simulations were able to reproduce a forest of jets because they explored a more realistic range of parameters than earlier studies.

Conclusion

• This novel coming together of solar astronomers and condensed matter experimentalists was able to reveal the underlying cause of the poorly understood solar spicules.
• The power of unifying physics that connects physically disparate phenomena will prove to be the driving force of much more interdisciplinary collaboration.