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photosphere
شیدسپهر، رخشانسپهر
šidsepehr, raxšânsepehr
Fr.: photosphère
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The visible surface of the Sun (temperature 5700 K), just below the
→ chromosphere and just above the
→ convective zone.
The solar photosphere is a thin layer of roughly 300 km wide.
Its temperature decreases uniformly with height,
from about 6,600 K (pressure 0.868
→ millibars) at its bottom, to about 4,400 K (pressure 125 mb),
where it merges with the chromosphere. The photosphere has a
“rice-grain” appearance, called
→ granulation, caused by rising (hot) and falling (cool)
material in the → convective cells just below the photosphere.
Other main features of the photosphere are → sunspots,
→ faculae, and → supergranulation.
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The region of a star which gives rise to the continuum radiation
emitted by the star.
See also: → photo- + → sphere.
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