Vertical distribution of stars and flaring in the Milky Way

Abstract

AbstractWe study the vertical stellar distribution of the Milky Way thin disk treated as a gravitationally coupled system of stars, HI and H2 gas in the field of dark matter halo, from R = 4 to 22 kpc. We show that the gas and halo gravity mainly constrain this vertical distribution toward the mid-plane in the inner and the outer Galaxy, respectively. The halo gravity reduces the disk thickness by a factor of 3-4 in the outer Galaxy. Despite this constraining effect the disk thickness increases steadily with radius, flaring steeply beyond 17 kpc, making a flaring disk a generic result.