Evershed effect

The Evershed effect is the radially outward flow of gas over the photosphere surface of the sun from the inner penumbra boundary of a sunspot to the outer boundary of the penumbra.

The speed of the river goes from 1 km per second at the border between the umbra and penumbra to a maximum of 2.5 km per second in the middle of the penumbra. In individual cases, speeds of 6 km per second were also measured.

The phenomenon was first observed by the British astronomer John Evershed (1864–1956) in 1909 when he was working at the Kodaikanal Solar Observatory in India and studying the Doppler shift of the spectral lines in sunspots.

Individual evidence

^ ^A ^b A. Bhatnagar, William Charles Livingston: Fundamentals of Solar Astronomy . 2005, ISBN 978-981-256-787-1 , 5.1.2.2 Motions in Sunspot Penumbrae, pp. 191-194 .

[bhatnagar2005-1] A ^b A. Bhatnagar, William Charles Livingston: Fundamentals of Solar Astronomy . 2005, ISBN 978-981-256-787-1 , 5.1.2.2 Motions in Sunspot Penumbrae, pp. 191-194 .