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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 center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...
's chromosphere
A chromosphere ("sphere of color") is the second layer of a star's atmosphere, located above the photosphere and below the solar transition region and corona. The term usually refers to the Sun's chromosphere, but not exclusively.
In the S ...
, typically found in and around active regions
An active region is a temporary region in the Sun's atmosphere characterized by a strong and complex magnetic field. They are often associated with sunspots and are commonly the source of violent eruptions such as coronal mass ejections and solar ...
. 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 byHenri-Alexandre Deslandres
Henri Alexandre Deslandres (24 July 1853 – 15 January 1948) was a French astronomer, director of the Meudon and Paris Observatories, who carried out intensive studies on the behaviour of the atmosphere of the Sun.
Biography
Deslandres' und ...
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 dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...
s. but nowadays most researchers identify plage based on the photospheric magnetic field concentration of the faculae 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 nearly periodic 11-year change in the Sun's activity measured in terms of variations in the number of observed sunspots on the Sun's surfa ...
* 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