Definitions for color index
col·or in·dex

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1. Color index

   In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. The lower the color index, the more blue (or hotter) the object is. Conversely, the larger the color index, the more red (or cooler) the object is. This is a consequence of the logarithmic magnitude scale, in which brighter objects have smaller (more negative) magnitudes than dimmer ones. For comparison, the whitish Sun has a B−V index of 0.656 ± 0.005, whereas the bluish Rigel has a B−V of −0.03 (its B magnitude is 0.09 and its V magnitude is 0.12, B−V = −0.03). Traditionally, the color index uses Vega as a zero point. To measure the index, one observes the magnitude of an object successively through two different filters, such as U and B, or B and V, where U is sensitive to ultraviolet rays, B is sensitive to blue light, and V is sensitive to visible (green-yellow) light (see also: UBV system). The set of passbands or filters is called a photometric system. The difference in magnitudes found with these filters is called the U−B or B−V color index respectively.

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1. Color index

   In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. The smaller the color index, the more blue the object is. Conversely, the larger the color index, the more red the object is. This is a consequence of the logarithmic magnitude scale, in which brighter objects have smaller magnitudes than dimmer ones. For comparison, the yellowish Sun has a B–V index of 0.656 ± 0.005, while the bluish Rigel has a B–V of –0.03. To measure the index, one observes the magnitude of an object successively through two different filters, such as U and B, or B and V, where U is sensitive to ultraviolet rays, B is sensitive to blue light, and V is sensitive to visible light. The set of passbands or filters is called a photometric system. The difference in magnitudes found with these filters is called the U-B or B–V color index, respectively. In principle, the temperature of a star can be calculated directly from the B-V index, and there are in the literature several formulae to make this connection. A good approximation can be obtained by considering stars as black bodies, using Ballesteros' formula:

How to pronounce color index?

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How to say color index in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of color index in Chaldean Numerology is: 6

2. Pythagorean Numerology

   The numerical value of color index in Pythagorean Numerology is: 2

References

1. ^ Wikipedia
   https://en.wikipedia.org/wiki/Color_Index
2. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=color index