Color Index:
The color index of a star is the difference between two measurements of the magnitude (brightness on a logarithmic scale) of a star made at different wavelengths, ...
color index A convenient method of quantifying a star's color by comparing its apparent brightness as measured through different filters.
COLOR INDEX - Parameter defining how a star's brightness varies with color. It is defined by taking the difference in magnitude (which is related logarithmically to intensity) at different wavelengths.
Color Index
Difference between the photographic and photovisual magnitudes of a star; or more generally, the difference in magnitudes between any two spectral regions.
Color Index and Temperature
Wien's Law and Temperature
Review Questions
The Composition of Stars
The Velocities of Stars Doppler Effect ...
Color index
A measure of a star's color, which tells scientists how hot the stars surface is.
Coma ...
Color Index: The difference in a star's brightness (magnitude) as measured in two different wavelength bands. For example, suppose one of the two bands were centered on red and the other on blue.
color index - (n.)
The difference B-V between the blue (B) and visual (V) magnitudes of a star. If B is less than V (that is, the star is brighter in blue than in visual light), then the star has a negative color index, and is a relatively hot star.
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73. Color Index
A numerical measure of the color of a star.
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74. Comet
One of the small, icy bodies that orbit the sun and produce tails of gas and dust when they near the sun.
Finally, since the color index is measured in logarithmic magnitudes, this corresponds to a ratio of brightnesses in linear units.
Temperature, luminosity and chemical abundances ...
color equation (NASA SP-7, 1965) In astronomy, a measure of the color sensitivity of a method of observation, equal to the color index of a class K0 star. color excess (NASA SP-7, 1965) (symbol E) ...
So a star that had more light in the blue band than in the visual band would have a B-V color index that was less than zero (B less than V).
One can also predict from such results the expected history of any particular color index or line strength.
(a) Measurement of the astronomical color index of a star, utilizing the ultraviolet, blue and yellow visual images over two pre-set wavelengths obtained by photoelectric filtering. Other standardized filter wavebands are also used. [A84] ...
The Hertzsprung-Russell diagram (HR-diagram) is a graph of a large sample of stars that plots their visual absolute magnitude against their color index.
One is the observer's form which plots the color index of the star on one axis and the absolute magnitude on the other axis. These two quantities can be derived from observations.
A Hertzsprung-Russell diagram plots the actual brightness (or absolute magnitude) of a star against its color index (represented as B-V). The main sequence is visible as a prominent diagonal band that runs from the upper left to the lower right.
The main sequence is a continuous and distinctive band of stars that appear on plots of stellar Color index versus brightness.
From the Hipparcos-Yale-Gliese database, a plot of stellar absolute magnitude on BV color index, also showing surface temperature and radius; 30,600 stars within 120 parsecs (400 light years) of the sun are indicated by spectral type; ...
Hertzsprung-Russell (H-R) diagram - A plot of absolute magnitude against temperature (or spectral class or color index) for a group of stars.
 See also: Magnitude, Temperature, Apparent, Light, Atmosphere
  
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