Answer:
Sunspots, Solar flares, and Coronal mass ejections (CMEs).
Explanation:
<em>Sunspots:</em>
Sunspot pair surface phenomena occur when a magnetic flux tube breaks the star's surface, loops about, and then re-enters the star. These tubes have broken the surface after rising buoyantly from the internal depths. The lengthy response is substantially more difficult because the entire procedure is so challenging! Let's start with the most basic question: Why do magnetic flux tubes rise to the surface buoyantly at all? If you visualize a star in thermal equilibrium with a single, isolated horizontal (i.e., perpendicular to the direction of gravity) magnetic field tube. With the subscripts I for within the tube and e for outside the tube, the fluid's attributes are pressure, density, and temperature. Since stars are essentially in a state of hydrostatic equilibrium, the pressure inside and outside of the tube must be identical. However, because of the magnetic field, there is also magnetic pressure inside the tube. Thus, p e = p e + p m, where p m is the magnetic pressure, is what we have. Now that we are in thermal equilibrium, we can assume that T i = T e = T, the temperature inside and outside, is the same since thermal diffusion moves far more quickly than ohmic (magnetic) or viscous molecules. Since rho e > rho i must be true for these two sides to be in balance, the region with the magnetic field will rise since it is less dense and buoyant than the other side. In two truly outstanding publications published in 1955, Eugine Parker originally defined this process. He basically came up with a lot of theories about how the Sun's various aspects would develop, and after decades of testing, nearly all of these theories have proven to be accurate. He inspired the Parker Solar Probe, which I think is the first and only mission NASA has launched into orbit with his name attached. The reason why a tube of magnetic flux might ever form at the surface is solely explained by this one step (the answer being that it rises there from the deep interior due to a mechanism known as magnetic buoyancy). There is much more to this, including why the Sun even has a magnetic field, how it maintains the field, why sunspots are dark, why they behave in such a predictable way (see the butterfly diagram, which depicts the 11 or 22-year solar cycle by which sunspot pairs reverse polarity, migrate, and cycle in occurrence rate) and much more!
<em>Solar flares:</em>
An enormous, unexpected burst of energy from the Sun is known as a solar flare. They don't pose a serious threat to humanity since the Earth's atmosphere effectively shields us from them. However, they could be harmful to people and spacecraft beyond the Earth's atmosphere. A far greater event known as a Coronal Mass Ejection (CME), which involves the emission of a tremendous amount of energy as well as matter, can occasionally occur alongside solar flares. Again, the atmosphere and magnetosphere of the Earth provide protection for us people on the ground. Theoretically, if a CME orders of magnitude larger than anything we've ever seen were to be directed at Earth for some reason, it could overwhelm the magnetosphere and atmosphere and have a significant negative impact on biological life. However, at that point, you're not talking about a solar flare or a CME; rather, you're talking about some other mechanism that is disrupting the Sun.
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<em>Coronal mass ejections:</em>
Strong, protracted solar flares and filament eruptions can cause large clouds of solar plasma, known as coronal mass ejections (or CMEs), to be flung away from the Sun. The OSO 7 spacecraft's coronagraph observations between 1971 and 1973 provided the first evidence of these dynamic occurrences. A tiny disk placed over the Sun by a coronagraph causes a solar eclipse. Because they are so weak, coronal mass ejections cannot be seen in any other way. White-light coronagraphs are equipped with the SOHO and STEREO spacecraft to find coronal mass ejections. Strong geomagnetic storms are mostly caused by coronal mass ejections, making them crucial to monitor. A coronal mass ejection is seen in the animation below as viewed by LASCO on board the SOHO satellite.
