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The assumption here is that either the extinction coefficient or the column number density is known. These can generally be calculated from other equations if a fair amount of information is known about the chemical makeup of the star.
In astronomy, the curve of growth describes the equivalent width of a spectral line as a function of the column density of the material from which the spectral line is observed. [ 1 ] Shape
A special type of area density is called column density (also columnar mass density or simply column density), denoted ρ A or σ. It is the mass of substance per unit area integrated along a path; [ 1 ] It is obtained integrating volumetric density ρ {\displaystyle \rho } over a column: [ 2 ] σ = ∫ ρ d s . {\displaystyle \sigma =\int \rho ...
ρ 0 is the density of air at sea level; H is the scale height of the atmosphere; z is the height in question; The optical depth of a plane parallel cloud layer is given by [3] = [] / where: Q e is the extinction efficiency; L is the liquid water path
In astronomy, air mass or airmass is a measure of the amount of air along the line of sight when observing a star or other celestial source from below Earth's atmosphere . It is formulated as the integral of air density along the light ray .
Column density is a commonly used measure in astronomy for the quantity of a given chemical element or molecule in a certain direction. In this region, the typical column density of neutral hydrogen is N H = 0.6 x 10 20 cm −2. [4] This column density is moderately lower than typical values near the galactic poles, where N H 10 20 cm −2, and ...
Column number density is a kind of areal density, the number or count of a substance per unit area, obtained integrating volumetric number density along a vertical path: ′ =. It's related to column mass density , with the volumetric number density replaced by the volume mass density.
Toggle the table of contents. ... and the column density of neutral hydrogen atoms column, N H ... Astronomy and Astrophysics. 322: 633–645.