A Universal Vertical Stellar Density Distribution Law for the Galaxy

TL;DR

This paper proposes a universal exponential density law for stars in the Milky Way, simplifying the vertical structure without needing separate scale heights or population classifications, and fits observational data well.

Contribution

It introduces a single density law applicable up to 8 kpc from the galactic plane, unifying thin and thick disc structures without separate parameters.

Findings

The proposed law fits observational data in the ELAIS field.

Classical models show offsets from observed densities.

A single structure model is sufficient for several kiloparsecs.

Abstract

We reduced the observational logarithmic space densities in the vertical direction up to 8 kpc from the galactic plane, for stars with absolute magnitudes (5,6], (6,7] and [5,10] in the fields $#$0952+5245 and SA114, to a single exponential density law. One of three parameters in the quadratic expression of the density law corresponds to the local space density for stars with absolute magnitudes in question. There is no need of any definition for scaleheights or population types. We confirm with the arguments of non-discrete thin and thick discs for our Galaxy and propose a single structure up to several kiloparsecs from the galactic plane. The logarithmic space densities evaluated by this law for the ELAIS field fit to the observational ones. Whereas, there are considerable offsets for the logarithmic space densities produced by two sets of classical galactic model parameters from the observational ones, for the same field.