Although it is the closest star to Earth and our own existence depends entirely on it, the Sun continues to hide a large number of secrets. For example, we still don't know why his crown, the outermost layer of its atmosphere, where the solar wind originates, maintains temperatures that exceed one million degrees Celsius, while the surface does not exceed 6,000 degrees.
In August 2018, NASA launched the Parker Solar Probe towards the Sun, a sophisticated mission whose goal is to approach our private star like never before. And the goal is precisely to identify the mechanisms behind the enormous heating of the crown and the acceleration of the solar wind, a continuous flow of plasma particles that expands through space and "floods" the entire Solar System. This same week, four different studies in Nature report the first results of the probe, which has become the human ingenuity that has managed to get closer to the Sun.
Until «touch» the Sun
The measurements of the Solar Probe were, in effect, taken "only" 24 million kilometers away from the Sun, half of what separates the star king of Mercury and much closer than any previous measurement. And those data have shown that, near the Sun, the solar wind is much more structured and dynamic than we measured here on Earth. In the next few years, the probe will continue to approach the star, until it is just 6,000,000 kilometers away from its surface.
The corona produces solar wind, very energetic particles that steer clear of the Sun. The observations made so far, from far away, have discovered the details of some mechanisms that underlie the creation of these solar winds, but other processes have been harder to explore. In fact, most of the measurements have been made at a distance of 1 astronomical unit, 150,000,000 km, which is the distance between the Earth and the Sun.
Now, however, the Parker Solar Probe has approached the crown more than any previous mission and has begun making observations that were impossible until now. For example, previous missions had shown that the solar wind accelerates when it leaves the crown, but no one had managed to explain what is the mechanism that produces that acceleration.
In one of Nature's studies, Stuart Bale and his team at the University of California at Berkeley present measurements of the direction and strength of the solar magnetic field, which is dragged into space by the solar wind. The authors have witnessed a series of rapid reversals in the direction of the magnetic field, lasting just a few minutes and whose nature is completely unknown.
Field investments and accelerated particles
For his part, Justin Kasper and his team at the University of Michigan present in Nature their observations on plasma, composed of ions and electrons. And found that investments in the sun's magnetic field are often associated with plasma velocity in its distance from the solar center, giving rise to S-shaped curves that travel along the field lines that come from the Sun.
In the third study, David McComas and his colleagues at Princeton University have studied how solar wind particles are accelerated by corona eruptions (of radiation), or by the shock waves associated with coronal mass ejections (plasma), which once expelled travel through the interplanetary space. The authors have analyzed particles from both sources and have found that the geometry of the magnetic field is much more complicated than previously believed. An "extra" complication that could be due to the aforementioned investments of the S-shaped magnetic field.
A "hole" near the Sun
Finally, Russel Howard, of the US Naval Research Laboratory, explains in his study that the intensity of radiation scattered by dust decreases with distance from the Sun, and announces the finding of a hypothetical dust-free area very close to the star and that had not been detected so far.
Together, the four Nature articles show that, after having penetrated an unexplored region, the Parker Solar Probe has already begun to make great discoveries.
Over the next five years, this probe will continue to make new discoveries as it gets closer and closer to the Sun, finally reaching just over six million kilometers of its surface. During this time, the Sun will enter a more active phase of its eleven year cycle, so we can expect really exciting results.
. (tagsToTranslate) results (t) parker (t) nasa