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Where do dark spots on the sun come from?
An image of the sunspot taken in blue light where the spatial resolution is highest. The image has been colorized for aesthetic reasons. The sunspot consists of the central dark umbra surrounded by the filamentary penumbra. The spot is surrounded by granulation. This image with 0.1 arcsecond resolution from the Swedish 1-m Solar Telescope represents the limit of what is currently possible in terms of spatial resolution.
[The Royal Swedish Academy of Sciences, Vasco M.J. Henriques]
Dark spots on the Sun are created by the movement of gases, a new study in the journal Science reports.
Sunspots are dark regions of the sun that appear black because they are cooler than the rest of the sun's visible surface.
Understanding dark cores may help scientists to better understand the fine structure of the magnetic filaments that make up sunspots.
An image of the sunspot with the Earth shown to scale. The image has been colorized for aesthetic reasons. This image with 0.1 arcsecond resolution from the Swedish 1-m Solar Telescope represents the limit of what is currently possible in terms of spatial resolution.
[The Royal Swedish Academy of Sciences, V.M.J. Henriques (sunspot), NASA Apollo 17 (Earth)]
Physicists believe that these magnetic filaments get so tangled that they end up looping out of the Sun's surface.
The darkest part of a sunspot is called the umbra; this is where the magnetic filaments pop out of the Sun's surface. Surrounding the umbra is the penumbra, where more filaments clustered.
In the study, Göran Scharmer and colleagues provide evidence that the flow of hot and cold gases—called convective flow—is responsible for the formation of dark cores in sunspots.
Using data from NASA's Spitzer Space Telescope, the researchers were able to probe the deepest layers of the solar atmosphere to look for signs of small-scale gas flow and subsequently create computer simulations of sunspot convection.
Their results support the idea that the numerous, thin filaments of dark cores (the penumbra) are made up of columns of gases generated by convective flow.