Tiny bright dots are everywhere on the Sun, and we can finally find out their source

(ORDO NEWS) — Sunspots are not the only specks that adorn the dynamic face of our Sun. Solar physicists have closely studied the tiny, fleeting patches of brightness that appear and disappear in less than a minute on average in regions where loops of plasma rise from the solar surface.

They were called “solar points”. The analysis showed that this fleeting phenomenon is most likely the result of magnetic machinations – which would not be surprising, given that changes in the magnetic field play a huge role in all sorts of strange solar phenomena.

However, the find suggests that the Sun is even more complex than we thought; analysis of these solar freckles can improve our understanding of the role of the magnetic field in solar dynamics and the magnetic field itself.

The fascinating dots were spotted in images taken by the NASA-ESA Solar Orbiter, which was launched in 2020, just as the Sun was just entering a new cycle and becoming increasingly active.

On May 20, 2020, the spacecraft took pictures of some areas of magnetic flux with magnetic loops rising from the solar photosphere.

The solar magnetic field is a complex beast. It is generated by the dynamo process in the bowels of the Sun – the movement of a convecting, conductive fluid that generates electric and magnetic fields. We don’t know exactly how this works, but the resulting magnetic field lines are numerous, dynamic, and complex.

Sunspots, for example, are areas where magnetic fields are particularly strong, and solar flares and coronal mass ejections result from magnetic field lines breaking and rejoining.

The 11-year solar cycles mentioned earlier are due to a change in the magnetic field that occurs every 11 years when the sun’s magnetic poles are reversed.

Led by astrophysicist Sanjiv Tiwari of Lockheed Martin’s Solar and Astrophysics Laboratory, a team of scientists took a closer look at one of the magnetic flux regions, capturing an image in extreme ultraviolet wavelengths. They found tiny round spots of brightness almost hidden in the solar plasma.

As a result of image processing, these points became more visible, which allowed the team to study them in detail. Within an hour, they were able to observe and characterize about 170 points.

Overall, the dots averaged about 675 kilometers (420 miles) in diameter (small for the Sun), were about 30 percent brighter than the surrounding plasma, and lasted only 50 seconds on average before disappearing again.

About half of the dots remained isolated throughout their short lives, while the rest split in two, merged with other dots, or developed explosive loops or jets.

Comparison with NASA’s Solar Dynamics Observatory data showing the Sun’s magnetic field showed that dots appear throughout Solar Orbiter’s field of view, but cluster more densely in more magnetically active regions, especially large and bright dots.

The next step was to try to find out the cause of the specks. This required the use of the Bifrost software, which models the magnetohydrodynamics of the solar atmosphere.

Modeling has shown that the dots can be magnetic reconnection moments between magnetic field lines emerging from the solar surface and magnetic field lines descending into it.

Since magnetic reconnection in the solar atmosphere leads to the formation of loops, this explains why many of the points in the process of evolution are stretched into an elongated loop.

However, some dots did not appear in regions with entangled magnetic fields, suggesting that there are multiple pathways for the formation of these enigmatic features. One possible explanation, the team says, is the propagation of magnetoacoustic waves in the solar plasma, which can create impacts that result in dots.

But the mystery is still far from being solved. The points obtained using the Solar Orbiter are not the only points observed on the Sun, and they have been observed at different wavelengths and in different magnetic environments.

Future research, the team says, could help resolve these open questions, bringing us closer to a true understanding of our amazing star.


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