Parametrization of the Galactic structure by two exponentials

Abstract

We parametrized the total structure of the Galaxy in cylindrical coordinates up to z similar to 10 kpc by using radial and vertical exponentials, covering the thin and thick disc and the inner spheroid. However, we allowed the scale height and scale length to vary continuously with distance from the Galactic plane. The standard deviations for the differences between stellar space densities estimated by means of the newly defined scale heights and scale lengths and the observed space densities for three absolute magnitude intervals, 5 < M(g') <= 6, 6 < M(g') <= 7, and 7 < M(g') <= 8, of the fields SA 114, ELAIS, and # 0952+5245 are rather small. The uncertainties of the scale heights are also small, indicating that this parameter depends very sensitively on the distance from the Galactic plane, whereas those of the scale lengths are larger.