Hertzsprung-Russell diagram

Hertzsprung-Russell diagram

[hairt-sproong-ruhs-uhl]
noun Astronomy.
the graph showing the absolute magnitude plotted against the surface temperature for a group of stars.
Also called H-R diagram.


Origin:
after Danish astronomer Ejnar Hertzsprung (1873–1967) and H. N. Russell, who compiled the data on which it is based

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World English Dictionary
Hertzsprung-Russell diagram (ˈhɜːtssprʌŋˈrʌsəl)
 
n
See also main sequence a graph in which the spectral types of stars are plotted against their absolute magnitudes. Stars fall into different groupings in different parts of the graph
 
[C20: named after Ejnar Hertzsprung and Henry Norris Russell]

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Science Dictionary
Hertzsprung-Russell diagram  
A graph in which the absolute magnitude (intrinsic luminosity) of stars is plotted vertically against their surface temperatures (or corresponding spectral types). The diagram shows a strong correlation between luminosity and surface temperature among the average-size stars known as dwarfs, with hot, blue stars having the highest luminosities and relatively cool, red stars having the lowest. The roughly diagonal line (running from the upper left of the diagram to the lower right) that shows this correlation is called the main sequence. Giant and supergiant stars have relatively high luminosities for their surface temperatures and are positioned on the diagram above the main sequence. The faint white dwarfs have relatively low luminosities for their surface temperatures and cluster below the main sequence. See more at main sequence.
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