Architecture of the sun

Granulation, plages and prominences

By Gary Zientara
For The Taos News
Posted 4/25/19

This image of our sun was taken with the new solar telescope at the Girl Scouts of New Mexico Trails camp Elliott Barker near Angel Fire, New Mexico. The grainy orange peel-like texture of the …

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Architecture of the sun

Granulation, plages and prominences

Posted

This image of our sun was taken with the new solar telescope at the Girl Scouts of New Mexico Trails camp Elliott Barker near Angel Fire, New Mexico. The grainy orange peel-like texture of the visible color surface of the sun (chromosphere) is made up of thousands of individual convective columns of mostly hydrogen gas heated by the nuclear fusion "furnace" located at the sun's core. This texture is called "granulation" and each convective column (granule) is about the size of the United States.

The bright yellow boomerang shaped spot located near the lower center portion of the sun's disk is a hot spot called a "plage." Plage (plahj) is derived from the French word for "beach." Plages are usually found around sunspots but they can form by themselves as you see in this image.

The "flames" that stick out from the edge of the sun that you see along the bottom of this image are large masses of plasma (superheated gas) called "prominences" that billow out thousands of miles into space. They are shaped by magnetic fields which cause them to spike and even to loop back into the sun. Each of the prominences you see here are at least the size of the Earth. When prominences occur on the face of the sun, they form dark curved wormlike shapes called, "filaments."

There are no dark sunspots in this image. That's because the sun is still at the quiescent phase of its 11-year solar cycle known as "solar minimum." In fact, it is in the 24th cycle since we began charting them and this cycle is a comparatively weak one. The relatively dark edge of the sun is caused by a phenomenon called "limb darkening." It is a characteristic of stars where the center is brightest because you can see deeper (greater optical depth) into the star straight on. The optical depth at the edge or limb of a star is shallower and hence, darker.

Even though our sun is a yellow star, it looks somewhat red in this image because of the wavelength of light that is allowed to pass through this solar telescope's Hydrogen Alpha filter. The sun emits light at practically all wavelengths, but some of the sun's most interesting features radiate in the HA band which is near the red part of the visible spectrum. By using a filter that blocks all light but lets the HA band pass through, you can see features like prominences and filaments.

For more information and astronomical events for the next month, visit the website mountsangreobservatory.com.

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