Einasto profile
Encyclopedia
The Einasto profile is a mathematical function that describes how the density 
of a spherical stellar system varies with distance 
from its center. Jaan Einasto
introduced his model at a 1963 conference in Alma-Ata, Kazakhstan.
The Einasto profile has the form
The parameter
controls the degree of curvature of the profile. This can be seen by computing the slope on a log-log plot:
The larger
, the more rapidly the slope varies with radius (see figure). Einasto's law can be described as a generalization of a power law, 
, which has a constant slope on a log-log plot.
Einasto's law has the same mathematical form as Sersic's law, which is used to describe the surface brightness (i.e. projected density) profile of galaxies.
Einasto's model has been used to describe many types of system, including galaxies
and dark matter halo
s.
of a spherical stellar system varies with distance from its center. Jaan EinastoJaan Einasto
Jaan Einasto is an eminent Estonian astrophysicist and one of the discoverers of the cellular structure of the Universe....
introduced his model at a 1963 conference in Alma-Ata, Kazakhstan.
The Einasto profile has the form
The parameter
controls the degree of curvature of the profile. This can be seen by computing the slope on a log-log plot:The larger
, the more rapidly the slope varies with radius (see figure). Einasto's law can be described as a generalization of a power law, , which has a constant slope on a log-log plot.Einasto's law has the same mathematical form as Sersic's law, which is used to describe the surface brightness (i.e. projected density) profile of galaxies.
Einasto's model has been used to describe many types of system, including galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
and dark matter halo
Dark matter halo
A dark matter halo is a hypothetical component of a galaxy, which extends beyond the edge of the visible galaxy and dominates the total mass. Since they consist of dark matter, halos cannot be observed directly, but their existence is inferred through their effects on the motions of stars and gas...
s.
External links
- Spherical galaxy models with power-law logarithmic slope. A comprehensive paper that derives many properties of stellar systems obeying Einasto's law.