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The Z-factor defines a characteristic parameter of the capability of hit identification for each given assay. The following categorization of HTS assay quality by the value of the Z-Factor is a modification of Table 1 shown in Zhang et al. (1999); [2] note that the Z-factor cannot exceed one. Z-factor value. Related to screening.
Absolute magnitude is defined as the apparent magnitude that a star or object would have if it were observed from a distance of 10 parsecs (33 light-years; 3.1 × 10 14 kilometres; 1.9 × 10 14 miles). Therefore, it is of greater use in stellar astrophysics since it refers to a property of a star regardless of how close it is to Earth.
From this the luminosity distance (in meters) can be expressed as: The luminosity distance is related to the "comoving transverse distance" by. and with the angular diameter distance by the Etherington's reciprocity theorem: where z is the redshift. is a factor that allows calculation of the comoving distance between two objects with the same ...
The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth.
Air mass (astronomy) 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 (Green 1992). It is formulated as the integral of air density along the light ray. As it penetrates the atmosphere, light is attenuated by scattering and ...
Stellar age estimation. Various methods and tools are involved in stellar age estimation, an attempt to identify within reasonable degrees of confidence what the age of a star is. These methods include stellar evolutionary models, membership in a given star cluster or system, fitting the star with the standard spectral and luminosity ...
The complex conjugate is found by reflecting across the real axis. In mathematics, the complex conjugate of a complex number is the number with an equal real part and an imaginary part equal in magnitude but opposite in sign. That is, if and are real numbers then the complex conjugate of is The complex conjugate of is often denoted as or .
A star's metallicity measurement is one parameter that helps determine whether a star may have a giant planet, as there is a direct correlation between metallicity and the presence of a giant planet. Measurements have demonstrated the connection between a star's metallicity and gas giant planets, like Jupiter and Saturn .