![]() The object consists of what appear to be ropelike filaments, but the common explanation is that the expanding shock wave of heated gas forms a thin layer that is visible to us only when it is wrinkled and bunched up along our line of sight. The fact that we don’t have much experience with thin sheets of glowing gases in everyday life is likely part of the reason the wrinkled veil hypothesis hasn’t been seriously considered before, says Malanushenko.īut there are some astrophysical precedents in the night sky - most famously, the Veil Nebula, which consists of the remnants of an expanding cloud of debris from a supernova in the constellation Cygnus 10,000 to 20,000 years ago. ![]() Of course, because plasma in the solar corona is emitting light - not absorbing it - such wrinkles appear brighter to us, not darker. The effect is analogous to a thin veil: When the material bunches up so that we see it edge-on or is folded so that we are looking through multiple layers, it absorbs more light and blocks our view of what is behind it. ![]() Instead, they maintain a relatively even brightness from top to bottom.īut these inconsistencies go away under the veil hypothesis, where the loops don’t correspond to compact plasma strands, but are instead a perspective effect caused by wrinkles in a sheet of plasma. This means that the tops of coronal loops should also be thinner and therefore not as bright as at their bases. The other issue with the strands hypothesis is related to how the Sun’s atmosphere becomes less dense further away from its visible surface. ![]() “The consensus is that they do expand with height but not nearly as much as we think they should,” Malanushenko told Astronomy. That means if coronal loops are strands that trace magnetic field lines, they should also fan out and get wider high above the Sun’s surface. One is that magnetic field lines tend to fan out further from their source - whether that source is a bar magnet or a group of sunspots. However, there are a couple issues with the strands hypothesis that call it into question. Therefore, it’s not much of a stretch to think that these bright loops are thin strands of frozen-in plasma, following the curvature of the magnetic field. Physicists say that plasma is “frozen in” to a magnetic field: The magnetic force guides plasma along magnetic field lines, the same lines that iron filings trace out around a bar magnet. Because plasma consists of particles with an electric charge, their movements are influenced by the Sun’s magnetic field. This is an entirely new paradigm of understanding the Sun’s atmosphere.” Lifting the veilįor decades, scientists have generally assumed that coronal loops are what they look like - strands of hot glowing plasma. When I saw the results, my mind exploded. “I have spent my entire career studying coronal loops,” said Malanushenko, a researcher at the National Center for Atmospheric Research in Boulder, Colorado, and the study’s lead author, in a statement. The insight came from exploring simulations of the Sun’s magnetic field published March 2 in The Astrophysical Journal. The team call this the coronal veil, and they think that bright coronal loops appear where the veil is wrinkled and our line of sight runs through more of it. Instead, the loops may be an illusion rooted in a more complex structure - a magnetic sheet or curtain that is being pulled and wrinkled. Now, a team of solar physicists say these iconic structures may not actually be loops at all. Some of the most spectacular features on the Sun are its coronal loops - incandescent structures of hot plasma that arc for thousands of miles above magnetically active regions of the Sun, forming what appear to be curving strands.īut appearances can be deceiving. ![]()
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