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]
^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.
ISBN9780080568362.
^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.
S2CID220055853.
^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.
S2CID220055552.