A group of solar scientists led by Shadia Habbal has traveled around the world to scientifically observe total solar eclipses, the fleeting moments when the Moon covers the Sun, and temporarily turning the day into night.
But more than the pretty images they captured during total solar eclipses, these scientists have uncovered a surprising finding of the solar wind and the Sun's corona.
After more than ten years of observing solar eclipses, they noticed that the corona maintains a stable temperature, despite the dynamic changes to the region that occur during the solar cycle that happens every 11 years. Similarly, they found that the solar wind matches that same temperature.
They published the findings of their study, entitled Identifying the Coronal Source Regions of Solar Wind Streams from Total Solar Eclipse Observations and in situ Measurements Extending over a Solar Cycle, in the Astrophysical Journal Letters.
Observing Solar Eclipses
Solar eclipses have been used for centuries to study the universe, including deciphering the Sun's structure and explosive events. The kind of corona produced during total solar eclipses could not be mimicked by coronagraphs, and so, astronomers have to travel far-flung places on the planet to observe the corona during eclipses that occur every 12 to 18 months and only last for a few minutes.
According to NASA, the team traveled for 14 years around the world to observe solar eclipses. They captured high-resolution images of total solar eclipses from around the world and measured temperatures of particles in the innermost part of the corona, the source of the solar wind.
The team discovered that the amount of cooler particles, which were more abundant and contributed to most solar winds, were consistent at different times during the solar cycle while the sparse hotter material varied much more.
"That means that whatever is heating the majority of the corona and solar wind is not very dependent on the Sun's activity cycle," said Benjamin Boe, a solar researcher at the University of Hawaii, as quoted by NASA.
The report said that the findings are surprising because it could mean that majority of the solar wind originated from a source that is roughly consistent in temperature and might have wildly different speeds.
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NASA's ACE Spacecraft Reveals the Dynamic Properties of Solar Wind
The team compared their data with NASA's Advanced Composition Explorer spacecraft (ACE), which is located 1 million miles away from Earth in the direction of the Sun, SciTech Daily reported. The ACE spacecraft is essential in revealing the dynamic properties of the Sun and the solar wind.
The data from the spacecraft showed that variable speeds of the solar winds were distinguished by the variability of the iron charge states that are associated with them. Their observations suggest that the high-temperature sheaths around prominences were responsible for the dynamic solar winds and the occasional coronal mass ejection.
Scientists think that the sources of the solar wind and the solar wind itself have the same temperature because the speeds vary on the density of the region where the solar wind originated from. Fast-flying particles originated from low-density regions, while slower ones came from high-density regions.
That means that there is more energy for each particle in areas where there are fewer particles. Scientists compared it to slicing a cake. The fewer people there will be, the more slice of cake each person will get.
The new findings could help understand solar wind better, which is a key component of the space weather that can affect space-based communications and astronomical observing electronics.
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