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Spectral optical depth or spectral optical thickness is the natural logarithm of the ratio of incident to transmitted spectral radiant power through a material. [1] Optical depth is dimensionless , and in particular is not a length, though it is a monotonically increasing function of optical path length , and approaches zero as the path length ...
Optical depth and actual depth, and respectively, can vary widely depending on the absorptivity of the astrophysical environment. Indeed, τ {\displaystyle \tau } is able to show the relationship between these two quantities and can lead to a greater understanding of the structure inside a star .
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
Astrophysics terminology – physics-related acronyms; Catalog – collections of tabulated scientific data; Communications network – any network that functions primarily to communicate with spacecraft rather than performing astronomy; Data – astrophysical data not associated with any single catalog or observing program
The "Big Bang" scenario, with cosmic inflation and standard particle physics, is the only cosmological model consistent with the observed continuing expansion of space, the observed distribution of lighter elements in the universe (hydrogen, helium, and lithium), and the spatial texture of minute irregularities (anisotropies) in the CMB radiation.
In astrophysics, L is used for luminosity (energy per unit time, equivalent to power) and F is used for energy flux (energy per unit time per unit area, equivalent to intensity in terms of area, not solid angle). They are not new quantities, simply different names.
The skin depth is the distance which the wave can travel before its amplitude reduces by that same factor. The absorption coefficient is related to the penetration depth and skin depth by α = 1 / δ p e n = 2 / δ s k i n . {\displaystyle \alpha =1/\delta _{\mathrm {pen} }=2/\delta _{\mathrm {skin} }.}
Equations of radiative transfer have application in a wide variety of subjects including optics, astrophysics, atmospheric science, and remote sensing. Analytic solutions to the radiative transfer equation (RTE) exist for simple cases but for more realistic media, with complex multiple scattering effects, numerical methods are required.