What is photosphere?

  • (noun): The intensely luminous surface of a star (especially the sun).

Photosphere

The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived to emit light. It extends into a star's surface until the gas becomes opaque, equivalent to an optical depth of approximately 2/3. In other words, a photosphere is the deepest region of a luminous object, usually a star, that is transparent to photons of certain wavelengths.

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Some articles on photosphere:

Chromosphere
... It sits just above the photosphere and just below the solar transition region ... The density of the chromosphere is very small, it being only 10−4 times that of the photosphere, the layer just below it, and 10−8 times that of the atmosphere of Earth ... equipment, the chromosphere cannot normally be seen due to the overwhelming brightness of the photosphere ...
Stellar Atmosphere
... 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 ... The Sun's photosphere has a temperature in the 5,770 K to 5,780 K range ... Starspots, cool regions of disrupted magnetic field lie on the photosphere ...
Photosphere - Other Layers
... atmosphere has other layers above the photosphere the 2,000 kilometer-deep chromosphere (typically observed by filtered light, for example H-alpha) lies just between the photosphere and the ... Other "surface features" on the photosphere are solar flares and sunspots ...
Examples and Applications of Convection - Stellar Physics
... Granules on the photosphere of the Sun are the visible tops of convection cells in the photosphere, caused by convection of plasma in the photosphere ... Below the photosphere is a layer of much larger "supergranules" up to 30,000 kilometers in diameter, with lifespans of up to 24 hours ...
Granule (solar Physics)
... Granules on the photosphere of the Sun are caused by convection currents (thermal columns, Bénard cells) of plasma within the Sun's convective zone ... The grainy appearance of the solar photosphere is produced by the tops of these convective cells and is called granulation ... Below the photosphere is a layer of "supergranules" up to 30,000 kilometers in diameter with lifespans of up to 24 hours ...