Last year, NASA deployed one of its most ambitious projects, the Parker Solar Probe. Its mission: to get closer to the solar surface in order to learn more about its internal functioning. The US agency would like to answer two questions.
The first: why is the atmosphere of the Sun (crown) much hotter than its surface? “The crown is indeed heated to a million degrees, against only several thousand degrees for the solar surface,” said Tim Horbury of Imperial College London (UK). How is it possible ? “.
The second: what are the precise origins of the solar wind? Researchers believe that it has two main components: a “fast” wind traveling the space at about 700 km per second (from giant coronal holes in the polar region of the Sun). And a “slow” wind moving at about 500 km per second, whose origin is unknown.
First elements of the answer
So far the probe has made three orbits around the Sun, getting closer and closer. She just returned the first burst of data, giving us a beginning of a response to these questions.
What the probe has discovered is that this “slow wind” comes from small, spotted coronal holes around the solar equator. These structures had never been observed before. These small coronal holes appear to be colder and less dense regions, acting as channels allowing charged particles to flow into space.
Concerning the extreme heat of the corona, the observations made by the probe suggest that the particles contained in the solar wind seem to be released by jets of explosives, instead of being emitted by a constant flow. For researchers, it is this rapid release of energy from inside the Sun that helps explain why the atmosphere is so hot.
A zone “without dust”
The researchers also discovered that as the sun approaches, the dust begins to dissipate.
These cosmic crumbs are the result of collisions between planets, asteroids, comets and other celestial bodies operated billions of years ago. They flood our solar system. But it seems that at about 7 million kilometers from the Sun, dust volumes are starting to decrease steadily to the current limits of measurements made at a little over 4 million kilometers from the Sun.
Note that these first data were sent while the probe was about 24 million km from the Sun. It continues today and plans to move closer to about 6 million km from its surface in about six years. No ship has ever approached so close to our star.