Plage often appear as bright patches around active regions in the chromosphere. Plage are commonly observed around or surrounding sunspots, as both are phenomena associated with active regions.

A plage /pleɪdʒ/ is a bright region in the Sun's chromosphere, 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.[1]

Etymology

The term plage 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.[2]

Description

Classically plage have been defined as regions that are bright in Hα and other chromospheric emission lines. 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.[3][4]

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.[2]

See also

References

  1. ↑ Athay, R. Grant; Warwick, Constance S. (1961). "Indices of Solar Activity". In Landsberg, Helmut E.; Van Mieghem, J. (eds.). Advances in Geophysics. Vol. 8. Elsevier Science. p. 30. ISBN 9780080568362.
  2. 1 2 Pietrow, A.G.M. (2022). Physical properties of chromospheric features: Plage, peacock jets, and calibrating it all (PhD). Stockholm University. doi:10.13140/RG.2.2.36047.76968.
  3. ↑ Pietrow, A. G. M.; Kiselman, D.; de la Cruz Rodríguez, J.; Díaz Baso, C. J.; Pastor Yabar, A.; Yadav, R. (2020). "Inference of the chromospheric magnetic field configuration of solar plage using the Ca II 8542 Å line". Astronomy and Astrophysics. 644: 644. arXiv:2006.14486. Bibcode:2020A&A...644A..43P. doi:10.1051/0004-6361/202038750. S2CID 220055853.
  4. ↑ Morosin, Roberta; de la Cruz Rodríguez, Jaime; Vissers, Gregal J. M.; Yadav, Rahul (2020). "Stratification of canopy magnetic fields in a plage region. Constraints from a spatially-regularized weak-field approximation method". Astronomy and Astrophysics. 642: 642. arXiv:2006.14487. Bibcode:2020A&A...642A.210M. doi:10.1051/0004-6361/202038754. S2CID 220055552.
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