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In earlier Hertzsprung-Russell diagrams, the colours, as defined by the horizontal axis, showed the spectral type of the stars. This was an ordinal scale, not an exact numerical scale. The ordering was according to the surface temperature of the stars.
More recently, that has been replaced by the B-V colour scale. This is based on UBV photometry, where the amount of light given out by stars is measured in the ultraviolet (wavelength = 364 nm), blue (442 nm), and visual (540 nm) regions of the spectrum.
The value of V is subtracted from B and this is the B-V colour index which is used to colour-code stars. As a star gets cooler and therefore more red, the B-V colour index increases. Hot stars have a small B-V and cool stars have a large B-V.
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Where are 90 percent of stars on hr diagram?
main-sequence stars
What does fig mean?
a picture or diagram
Type of diagram showing relationships among sets?
Perhaps you mean the Venn diagram.
Did he had the concept of venn diagram?
The answer will depend on who you mean by HE.The answer will depend on who you mean by HE.The answer will depend on who you mean by HE.The answer will depend on who you mean by HE.
What does tape diagram mean in math?
Does it Mean like if u add the ratios like 2 to 3
