New study reveals higher temperature enhancements during acoustic shocks in the solar chromosphere

Source: The post is based on the article “New study reveals higher temperature enhancements during acoustic shocks in the solar chromosphere” published in PIB on 15th June 2023

What is the News?

A new study has found that bright grains observed in the chromosphere of the Sun are due to upward propagating shocks in the solar plasma, and show higher temperature enhancements than previous estimates.

What is Chromosphere?

A chromosphere is the second layer of a sun’s atmosphere, located above the photosphere and below the solar transition region and corona.

Chromosphere is roughly 3,000 to 5,000 kilometres in height, or slightly more than 1% of the Sun’s radius at maximum thickness.

The chromosphere emits a reddish glow as super-heated hydrogen burns off. But the red rim can only be seen during a total solar eclipse. At other times, light from the chromosphere is usually too weak to be seen against the brighter photosphere.

Chromosphere plays a crucial role in transferring energy (specifically non-thermal energy) that heats the corona and fuels the solar wind, which extends outward into the surrounding regions of the solar atmosphere.

Although a large portion of this energy is converted into heat and radiation, only a small fraction is actually used to heat the corona and power the solar wind.

How is the energy transmitted from the lower layers to the higher regions of the solar atmosphere?

There are currently two widely accepted mechanisms regarding how energy is transmitted from the lower layers to the higher regions of the solar atmosphere.

The first involves the rearrangement of the magnetic field lines, transitioning from higher to lower potential.

The second involves the propagation of different types of waves including acoustic waves.

Note: Acoustic shock waves are heating events in the chromosphere that appear as transient brightening in images and are called grains. The amount of energy these acoustic waves carry and how it heats the chromosphere is of fundamental interest in solar and plasma astrophysics.

What have the researchers found out?

Researchers have quantified the temperature enhancements during these acoustic shock events.

They have found that bright grains observed in the chromosphere of the Sun are due to upward propagating shocks in the solar plasma, and show higher temperature enhancements than previous estimates.

The study can help improve understanding of the mechanism of heating of the chromosphere situated between the bright solar surface and the extremely hot corona.