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A plage is a bright region in the
Encyclopedia of Astrobiology, Astronomy & Spaceflight: Plage
Stellar phenomena Solar phenomena {{sun-stub
A plage is a bright region in the Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
's chromosphere
A chromosphere ("sphere of color", from the Ancient Greek words χρῶμα (''khrôma'') 'color' and σφαῖρα (''sphaîra'') 'sphere') is the second layer of a Stellar atmosphere, star's atmosphere, located above the photosphere and below t ...
, typically found in and around active regions. Historically, they have been referred to as ''bright flocculi'', in contrast to dark flocculi, and as ''chromospheric faculae'', in contrast to photospheric faculae.
Etymology
The term is often believed to be poetically taken from the French word for "beach"; however, this is likely a misunderstanding of an 1893 article by Henri-Alexandre Deslandres where the name ''facular flames'' was suggested. In the article, Deslandres also refers to them as ''plages brillantes'', meaning ''bright regions'', which became the more commonly used term.Description
Classically, plage have been defined as regions that are bright in Hα and other chromosphericemission line
A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...
s. With modern imaging, most researchers now identify plage based on the photospheric magnetic field concentration of the faculae
Facula ( faculae) is a bright spot on the surface of a planet or a star. It may refer to
* Solar facula
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* Bright spots on Ceres
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{{disambig ...
below. The magnetic field of plage is confined to the intergranular lanes in the photosphere with a strength of around 1500 G, but expands into a volume filling canopy in the chromosphere with a field of around 450G.
It is believed that plage is formed from decaying emerging flux regions, and often acts as a footprint for coronal loops and fibrils, which makes them an important interface for coronal heating.
See also
*Solar cycle
The Solar cycle, also known as the solar magnetic activity cycle, sunspot cycle, or Schwabe cycle, is a periodic 11-year change in the Sun's activity measured in terms of Modern Maximum, variations in the number of observed sunspots on the Sun ...
* Solar spicule
In solar physics, a spicule, also known as a fibril or mottle, is a dynamic jet of plasma in the Sun's chromosphere about 300 km in diameter.Quantifying Spicules, Tiago M. D. Pereira, Bart De Pontieu, and Mats Carlsson, ''The Astrophysical ...
* Solar granule
References
External links
Encyclopedia of Astrobiology, Astronomy & Spaceflight: Plage
Stellar phenomena Solar phenomena {{sun-stub