Stellar atmosphere

Stellar atmosphere

Photo taken in France during the 1999 eclipse

The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. It is divided into several regions of distinct character:

  • The photosphere, which is the atmosphere's lowest and coolest layer, is normally its only visible part.[1] Light escaping from the surface of the star stems from this region and passes through the higher layers. The Sun's photosphere has a temperature in the 5,770 K to 5,780 K range.[2][3] Starspots, cool regions of disrupted magnetic field lie on the photosphere.[3]
  • Above the photosphere lies the chromosphere. This part of the atmosphere first cools down and then starts to heat up to about 10 times the temperature of the photosphere.
  • Above the chromosphere lies the transition region, where the temperature increases rapidly on a distance of only around 100 km.[4]

During a total solar eclipse, the photosphere of the Sun is obscured, revealing its atmosphere's other layers.[1] Observed during eclipse, the sun's chromosphere appears (briefly) as a thin pinkish arc,[7] and its corona is seen as a tufted halo. The same phenomenon in eclipsing binaries can make the chromosphere of giant stars visible.[8]

See also

Notes

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