The Einasto profile (or Einasto model) 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.
which can be rearranged to give
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 model has the same mathematical form as Sersic's law, which is used to describe the surface brightness (i.e. projected density) profile of galaxies.
- J. Einasto (1965), Kinematics and dynamics of stellar systems, Trudy Inst. Astrofiz. Alma-Ata 5, 87
- J. Einasto and U. Haud (1989), Galactic models with massive corona. I - Method. II - Galaxy Astron. Astrophys. 223, 89
- Merritt, David; Graham, Alister; et al. (2006). "Empirical Models for Dark Matter Halos". The Astronomical Journal. 132 (6): 2685–2700. arXiv:astro-ph/0509417. Bibcode:2006AJ....132.2685M. doi:10.1086/508988. S2CID 14511019.
- Spherical galaxy models with power-law logarithmic slope. A comprehensive paper that derives many properties of stellar systems obeying Einasto's law.