Stellar corona

A corona (pl.: coronas or coronae) is the outermost layer of a star's atmosphere. It is a hot but relatively dim region of plasma populated by intermittent coronal structures known as solar prominences or filaments.

The Sun's corona lies above the chromosphere and extends millions of kilometres into outer space. Coronal light is typically obscured by diffuse sky radiation and glare from the solar disk, but can be easily seen by the naked eye during a total solar eclipse or with a specialized coronagraph.^[1] Spectroscopic measurements indicate strong ionization in the corona and a plasma temperature in excess of 1000000 kelvins,^[2] much hotter than the surface of the Sun, known as the photosphere.

Corona (Latin for 'crown') is, in turn, derived from Ancient Greek κορώνη (korṓnē) 'garland, wreath'.

^ Liberatore, Alessandro; Capobianco, Gerardo; Fineschi, Silvano; Massone, Giuseppe; Zangrilli, Luca; Susino, Roberto; Nicolini, Gianalfredo (March 2022). "Sky Brightness Evaluation at Concordia Station, Dome C, Antarctica, for Ground-Based Observations of the Solar Corona". Solar Physics. 297 (3). arXiv:2201.00660. doi:10.1007/s11207-022-01958-x.
^ Aschwanden, Markus J. (2005). Physics of the Solar Corona: An Introduction with Problems and Solutions. Chichester, UK: Praxis Publishing. ISBN 978-3-540-22321-4.

[1] Liberatore, Alessandro; Capobianco, Gerardo; Fineschi, Silvano; Massone, Giuseppe; Zangrilli, Luca; Susino, Roberto; Nicolini, Gianalfredo (March 2022). "Sky Brightness Evaluation at Concordia Station, Dome C, Antarctica, for Ground-Based Observations of the Solar Corona". Solar Physics. 297 (3). arXiv:2201.00660. doi:10.1007/s11207-022-01958-x.

[Aschwanden-2] Aschwanden, Markus J. (2005). Physics of the Solar Corona: An Introduction with Problems and Solutions. Chichester, UK: Praxis Publishing. ISBN 978-3-540-22321-4.

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