2023-09-15 11:34:54
Illustration of the Solar Orbiter and Parker missions – NASA
MADRID, 15 Sep. (EUROPA PRESS) –
The combined use of ESA’s Solar Orbiter and NASA’s Parker missions is helping to solve the mystery of why the Sun’s atmosphere is so hot relative to the surface.
The scientists used data taken when The Parker Solar Probe sampled the Sun up close and the ESA/NASA Solar Orbiter observed it from further back.
The Sun’s atmosphere is called the corona. It is made up of an electrically charged gas called plasma and has a temperature of around one million degrees Celsius.
Its temperature is an enduring mystery because the Sun’s surface is only about 6,000 degrees. The corona should be colder than the surface because the Sun’s energy comes from the nuclear furnace at its core, and things naturally cool the farther they are from a heat source. However, the corona is more than 150 times hotter than the surface.
Another method must be working to transfer energy to the plasma, but which one? It has long been suspected that turbulence in the solar atmosphere could cause significant heating of the plasma in the corona. But when it comes to investigating this phenomenon, solar physicists run into a practical problem: it is impossible to collect all the data they need with a single spacecraft, explains ESA it’s a statement.
There are two ways to investigate the Sun: remote sensing and in situ measurements. In remote sensing, the spacecraft is placed at a certain distance and uses cameras to observe the Sun and its atmosphere at different wavelengths. For in situ measurements, the spacecraft flies through the region it wants to investigate and takes measurements of the particles and magnetic fields in that part of space.
Both approaches have their advantages. Remote sensing shows large-scale results, but not the details of the processes occurring in the plasma. Meanwhile, in situ measurements provide very specific information about small-scale processes in the plasma, but they do not show how this affects on a large scale.
To have a complete view, two spacecraft are needed. This is exactly what solar physicists currently have in the form of the ESA-led Solar Orbiter spacecraft and NASA’s Parker solar probe. Solar Orbiter is designed to get as close as possible to the Sun and still perform remote sensing operations, along with in situ measurements. Parker Solar Probe largely foregoes remote sensing of the Sun to get even closer for its in situ measurements.
But to take full advantage of its complementary approaches, Parker Solar Probe would have to be within the field of view of one of Solar Orbiter’s instruments. In this way, Solar Orbiter could record the large-scale consequences of what Parker Solar Probe was measuring in situ.
Daniele Telloni, a researcher at the Italian National Institute of Astrophysics (INAF) at the Turin Astrophysical Observatory, is part of the team behind Solar Orbiter’s Metis instrument. Metis is a coronagraph that blocks light from the Sun’s surface and takes photographs of the corona. It’s the perfect instrument for large-scale measurements, so Daniele began looking for moments when the Parker Solar Probe would align.
He found that on June 1, 2022, the two spacecraft would be in the correct orbital configuration, almost. Essentially, Solar Orbiter would be facing the Sun and Parker Solar Probe would be right to the side, tantalizingly close but out of the Metis instrument’s field of view.
As Telloni looked at the problem, he realized that all that was needed to get Parker Solar Probe into view was a 45-degree turn in Solar Orbite and then pointing it slightly away from the Sun.
With the maneuver, Parker Solar Probe entered the field of view and together, the spacecraft produced the first simultaneous measurements of the large-scale configuration of the solar corona and the microphysical properties of the plasma.
By comparing the newly measured rate with theoretical predictions that solar physicists have made over the years, Telloni has shown that solar physicists are almost certainly They were right to identify turbulence as a way of transferring energy.
The specific way turbulence does this is no different than what happens when you stir a cup of coffee. By stimulating random movements of a fluid, whether gaseous or liquid, energy is transferred at increasingly smaller scales, culminating in the transformation of energy into heat. In the case of the solar corona, the fluid is also magnetized and therefore Stored magnetic energy is also available to be converted to heat.
This transfer of magnetic energy and motion from larger to smaller scales is the very essence of turbulence. On the smallest scales, this allows the fluctuations to eventually interact with individual particles, mostly protons, and heat them.
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