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1\22 ESO - Distant World in Peril Discovered from La Silla- ALMA- AVO
Part 3 of 3

[3]: The diagram is named after Danish astronomer Einar Hertzsprung
(1873-1967) and American astronomer Henry Norris Russell (1877 - 
1957). At the beginning of the 20th century they independently noticed 
that red stars come in very different sizes, pioneering subsequent 
studies of stellar diameters. This diagram plots stellar temperature 
(or colour) against brightness (or magnitude) and is therefore also 
known as the "colour-magnitude diagram".

[4]: The (radial) velocity of a star is determined from its spectrum 
by measuring the (small) wavelength shift of the spectral lines, due 
to the Doppler effect.

Contacts

Johny Setiawan
Kiepenheuer Institut fuer Sonnenphysik
Freiburg, Germany
Tel: +49-761-3198160
email: setiawan{at}kis.uni-freiburg.de

Artie Hatzes
Thueringer Landessternwarte
Tautenburg, Germany
Tel: +49-36427-863-51
email: artie{at}jupiter.tls-tautenburg.de

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