Search results
Results from the WOW.Com Content Network
Optical depth in astrophysics refers to a specific level of transparency. Optical depth and actual depth, τ {\displaystyle \tau } and z {\displaystyle z} respectively, can vary widely depending on the absorptivity of the astrophysical environment.
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 ...
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.
The Planck collaboration version of the ΛCDM model is based on six parameters: baryon density parameter; dark matter density parameter; scalar spectral index; two parameters related to curvature fluctuation amplitude; and the probability that photons from the early universe will be scattered once on route (called reionization optical depth). [18]
The density, mass, and location of the objects in these lens populations determines the frequency of microlensing along that line of sight, which is characterized by a value known as the optical depth due to microlensing. (This is not to be confused with the more common meaning of optical depth, although it shares some properties.) The optical ...
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature, chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions.
The subdisciplines of theoretical astrophysics are: Compact objects – this subdiscipline studies very dense matter in white dwarfs and neutron stars and their effects on environments including accretion. Physical cosmology – origin and evolution of the universe as a whole. The study of cosmology is theoretical astrophysics at its largest scale.
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