NASAs Parker Solar Probe (PSP) has spotted the origin and structure of the solar wind close to the suns surface area, observing high-energy particles aligned with circulations in coronal holes. These holes are usually at the poles throughout the suns peaceful periods, so the quick solar wind they create does not hit Earth. When the sun becomes active every 11 years as its magnetic field turns, these holes appear all over the surface, creating bursts of solar wind intended straight at Earth.
By the time the solar wind reaches Earth, 93 million miles from the sun, it has progressed into an uniform, unstable flow of roiling magnetic fields intertwined with charged particles that interact with Earths own magnetic field and dispose electrical energy into the upper environment.” There was some consternation at the beginning of the solar probe mission that were going to release this thing right into the quietest, most dull part of the solar cycle,” Bale said.
NASAs Parker Solar Probe (PSP) has actually identified the origin and structure of the solar wind near the suns surface, observing high-energy particles lined up with flows in coronal holes. This discovery, suggesting magnetic reconnection within these regions, improves our understanding and forecasting of solar storms affecting Earth. Credit: NASA GSFC/CIL/Brian Monroe
NASAs Parker Solar Probe probe got close adequate to suns surface area to see surprise granular features.
NASAs Parker Solar Probe (PSP) has flown close enough to the sun to detect the great structure of the solar wind close to where it is produced at the suns surface, exposing information that are lost as the wind exits the corona as an uniform blast of charged particles.
Its like seeing jets of water emanating from a showerhead through the blast of water striking you in the face.
In a paper released on June 7 in the journal Nature, a team of researchers led by Stuart D. Bale, a professor of physics at the University of California, Berkeley, and James Drake of the University of Maryland-College Park, report that PSP has actually discovered streams of high-energy particles that match the supergranulation streams within coronal holes, which suggests that these are the regions where the so-called “quick” solar wind stems.
Coronal holes are areas where electromagnetic field lines emerge from the surface area without looping back inward, thus forming open field lines that expand outward and fill the majority of area around the sun. These holes are typically at the poles throughout the suns peaceful periods, so the fast solar wind they produce doesnt hit Earth. But when the sun becomes active every 11 years as its electromagnetic field turns, these holes appear all over the surface area, producing bursts of solar wind aimed straight at Earth.
Artists concept of the Parker Solar Probe spacecraft approaching the sun. Released in 2018, the probe is increasing our capability to anticipate major space-weather events that affect life in the world. Credit: NASA/Johns Hopkins APL/Steve Gribben
Understanding how and where the solar wind comes from will assist forecast solar storms that, while producing stunning auroras on Earth, can also create chaos with satellites and the electrical grid.
” Winds bring great deals of information from the sun to Earth, so comprehending the system behind the suns wind is very important for practical factors in the world,” Drake stated. “Thats going to affect our ability to understand how the sun launches energy and drives geomagnetic storms, which are a danger to our interaction networks.”
Based on the teams analysis, the coronal holes resemble showerheads, with approximately equally spaced jets emerging from bright areas where magnetic field lines funnel into and out of the surface of the sun. The researchers argue that when oppositely directed magnetic fields pass one another in these funnels, which can be 18,000 miles throughout, the fields often break and reconnect, slinging charged particles out of the sun.
“Where these supergranulation cells fulfill and go downward, they drag the magnetic field in their course into this downward kind of funnel. And the spatial separation of those little drains, those funnels, is what were seeing now with solar probe information.”
Based upon the presence of some very high-energy particles that PSP has spotted– particles taking a trip 10 to 100 times faster than the solar wind average– the scientists conclude that the wind could just be made by this process, which is called magnetic reconnection. The PSP was launched in 2018 mainly to solve 2 clashing explanations for the origin of the high-energy particles that make up the solar wind: magnetic reconnection or acceleration by plasma or Alfvén waves.
” The huge conclusion is that its magnetic reconnection within these funnel structures thats offering the energy source of the fast solar wind,” Bale said. It comes from these little packages of magnetic energy that are associated with the convection streams.
The funnel structures most likely correspond to the intense jetlets that can be seen from Earth within coronal holes, as reported just recently by Nour Raouafi, a co-author of the research study and the Parker Solar Probe task scientist at the Applied Physics Laboratory at Johns Hopkins University. APL created, developed, manages, and runs the spacecraft.
Plunging into the sun
By the time the solar wind reaches Earth, 93 million miles from the sun, it has actually progressed into an uniform, turbulent flow of roiling electromagnetic fields linked with charged particles that engage with Earths own electromagnetic field and dispose electrical energy into the upper environment. This delights atoms, producing vibrant auroras at the poles, however has results that trickle down into Earths environment. Predicting the most intense winds, called solar storms, and their near-Earth effects is one objective of NASAs Living With a Star program, which moneyed PSP.
The probe was created to identify what this rough wind looks like where its generated near the suns surface, or photosphere, and how the winds charged particles– protons, electrons, and much heavier ions, mostly helium nuclei– are accelerated to leave the suns gravity.
To do this, PSP needed to get closer than 25 to 30 solar radii, that is, closer than about 13 million miles.
” Once you get below that elevation, 25 or 30 solar radii or two, theres a lot less evolution of the solar wind, and its more structured– you see more of the imprints of what was on the sun,” Bale said.
In 2021, PSPs instruments tape-recorded electromagnetic field switchbacks in the Alfvén waves that seemed to be associated with the regions where the solar wind is produced. By the time the probe reached about 12 solar radii from the surface of the sun– 5.2 million miles– the information were clear that the probe was passing through jets of material, rather than simple turbulence. Bale, Drake, and their associates traced these jets back to the supergranulation cells in the photosphere, where magnetic fields lot up and funnel into the sun.
Were the charged particles being sped up in these funnels by magnetic reconnection, which would slingshot particles external, or by waves of hot plasma– ionized particles and magnetic field– streaming out of the sun, as if theyre surfing a wave?
The fact that PSP identified extremely high-energy particles in these jets– 10s to numerous kiloelectron volts (keV), versus a few keV for the majority of solar wind particles– told Bale that it needs to be magnetic reconnection that accelerates the particles and generates the Alfvén waves, which likely give the particles an additional increase.
” Our analysis is that these jets of reconnection outflow thrill Alfvén waves as they propagate out,” Bale said. “Thats an observation thats well understood from Earths magnetotail, too, where you have similar kinds of processes. I do not comprehend how wave damping can produce these hot particles as much as numerous keV, whereas it comes naturally out of the reconnection procedure. And we see it in our simulations, too. ”
The PSP will not be able to get any closer to the sun than about 8.8 solar radii above the surface area– about 4 million miles– without frying its instruments. Bale anticipates to solidify the groups conclusions with information from that altitude, though the sun is now going into solar maximum, when activity ends up being much more disorderly and might obscure the processes the researchers are trying to view.
” There was some consternation at the start of the solar probe mission that were going to introduce this thing right into the quietest, most dull part of the solar cycle,” Bale said. “But I think without that, we would never have actually understood this. It would have been simply too messy. I think were fortunate that we introduced it in the solar minimum.”
Referral: “Interchange reconnection as the source of the quick solar wind within coronal holes” by S. D. Bale, J. F. Drake, M. D. McManus, M. I. Desai, S. T. Badman, D. E. Larson, M. Swisdak, T. S. Horbury, N. E. Raouafi, T. Phan, M. Velli, D. J. McComas, C. M. S. Cohen, D. Mitchell, O. Panasenco and J. C. Kasper, 7 June 2023, Nature.DOI: 10.1038/ s41586-023-05955-3.