Our sun drives a continuing outward flow of plasma or ionized gas, called the solar wind, that envelops our solar system. Outside of Earth's protective magnetosphere fastest solar wind rushes past at speeds of over 500 kilometers per second. But researchers haven’t yet been capable of work out how the wind gets enough energy to achieve this speed.
Our team from Heliophysicist published an article in August 2024, indicating a brand new energy source for the solar wind.
Discovery of the solar wind
Physicist Eugene Parker predicted the existence of the solar wind in 1958The Mariner space probe on its option to Venus would confirm its existence in 1962.
Since the FortiesStudies had shown that the Solar corona or solar atmospherecould heat as much as very high temperatures – over 2 million degrees Fahrenheit (or greater than 1 million degrees Celsius).
Parker's work suggested that this high temperature could create an outward thermal pressure strong enough to beat gravity and permit the outer layer of the Sun's atmosphere to flee.
However, gaps in solar wind research quickly appeared as researchers made increasingly detailed measurements of the solar wind near Earth. In particular, they found two problems with the fastest a part of the solar wind.
For one thing, the solar wind continued to heat up after it left the recent corona without explanation. And even with this extra heat, the fastest wind was still didn’t have enough energy to clarify to scientists the way it was capable of speed up to such high speeds.
Both observations meant that there needed to be one other source of energy besides Parker's models.
NASA Goddard Space Flight Center Conceptual Image Lab
Alfvén waves
The sun and its solar wind are plasmas. Plasmas are like gasesbut all particles in plasmas are charged and react to magnetic fields.
Similar to how sound waves move through the air and transport energy on earth, plasmas are permeated by so-called Alfvén waves. For many years Alfvén waves had been predicted They influence the dynamics of the solar wind and play a very important role within the transport of energy within the solar wind.
However, scientists couldn’t say whether these waves actually interacted directly with the solar wind or whether or not they generated enough energy to drive it. To answer these questions, they would want to measure the solar wind very near the Sun.
In 2018 and 2020, NASA and the European Space Agency launched their respective flagship missions: the Parker Solar Probe and the Solar OrbiterBoth missions the proper instruments to measure Alfvén waves near the Sun.
The Solar Orbiter Ventures between 1 astronomical unit, where the Earth is, and 0.3 astronomical units, barely closer to the Sun than Mercury. The Parker Solar Probe dives much deeperIt comes inside five solar diameters of the Sun, inside the Outer edges of the corona. Each sun's diameter is about 865,000 miles (1,400,000 kilometers).
Arya Francesco
By working together, these two missions will allow researchers like us to not only study the solar wind near the Sun, but additionally study its changes between where Parker sees it and where Solar Orbiter sees it.
Magnetic serpentines
During Parker’s first approach to the Sun observed that the solar wind near the sun was indeed wealthy in Alfvén waves.
Scientists used Parker to measure the magnetic field of the solar wind. In some places they noticed that the sector lines – or magnetic lines of force – swung with such large amplitudes that they briefly modified direction. Scientists called these phenomena Magnetic serpentinesWith Parker, they observed these energetic plasma fluctuations throughout the solar wind near the Sun.
Our research team wanted to search out out if these serpentines contained enough energy to speed up and warmth the solar wind because it moved away from the Sun. We also wanted to check how the solar wind modified as these serpentines released their energy. This would help us determine if the serpentines' energy went into heating the wind, accelerating it, or each.
To answer these questions, we identified a novel spacecraft configuration by which each spacecraft crossed the identical section of the solar wind but at different distances from the Sun.
The secret of the serpentines
Parker, near the Sun, observed that about 10% of the solar wind energy was in magnetic gusts, while Solar Orbiter measured lower than 1%. This difference implies that between Parker and Solar Orbiter This wave energy was transmitted to other types of energy.
We some modelling carried outmuch like Eugene Parker hadWe built modern implementations of Parker's original models and integrated the influence of the observed wave energy into these original equations.
Specifically, by comparing the information sets and models, we could see that this energy contributed to each acceleration and heating. We knew it contributed to acceleration since the wind was stronger at Solar Orbiter than at Parker. And we knew it contributed to warming since the wind was hotter at Solar Orbiter than it might have been without the waves.
These measurements showed that the energy from the serpentines was each crucial and sufficient to clarify the evolution of the solar wind on its way from the Sun.
Our measurements not only provide scientists with insight into the physics of the solar wind and the way the Sun can affect the Earth, but they may even have implications for the whole universe.
Many other stars have Star winds that carry their material into space. Understanding the physics of the solar wind of our local star also helps us understand the stellar wind in other systems. Knowledge of the stellar wind could tell researchers more in regards to the Habitability of exoplanets.
image credit : theconversation.com