Analysis of the Z Distribution of Young Objects in the Galactic Thin Disk

TL;DR

This study estimates the Sun's position relative to the galactic plane and the vertical scale height of young objects in the galactic disk, using various stellar data to improve understanding of galactic structure.

Contribution

It provides new measurements of the Sun's offset from the galactic plane and the scale heights of young stellar populations, utilizing a comprehensive dataset and modeling approach.

Findings

Sun's distance from symmetry plane: -16 pc

Vertical scale height varies from 40 to 66 pc for different objects

Estimated about 5000 OB associations in the Galaxy

Abstract

We have obtained new estimates of the Sun's distance from the symmetry plane Zo and the vertical disk scale height h using currently available data on stellar OB associations, Wolf-Rayet stars, HII regions, and Cepheids. Based on individual determinations, we have calculated the mean Zo=-16+/-2 pc. Based on the model of a self-gravitating isothermal disk for the density distribution, we have found the following vertical disk scale heights: h = 40.2+/-2.1 pc from OB associations, h = 47.8+/-3.9 pc from Wolf-Rayet stars, h=48.4+/-2.5 pc from HII regions, and h = 66.2+/-1.6 pc from Cepheids. We have estimated the surface, \sum=6 kpc^{-2}, and volume, D(Zo) = 50.6 kpc^{-3}, densities from a sample of OB associations. We have found that there could be approximately 5000 OB associations in the Galaxy.