Estimation of the Gould Belt scale height from T Tauri type stars in the Gaia DR2 catalogue

TL;DR

This study estimates the Gould belt's scale height and kinematic properties using T Tauri stars from Gaia DR2, revealing its vertical structure, expansion, and rotation characteristics.

Contribution

It introduces a new method for excluding background stars and provides updated measurements of the Gould belt's scale height, expansion rate, and intrinsic rotation.

Findings

Gould belt scale height is approximately 56 pc.

The expansion rate of the system is about 6 km/s/kpc.

The belt exhibits an intrinsic rotation opposite to galactic rotation.

Abstract

We analyze the spatial and kinematic properties of a large sample of young T Tauri type stars in a 500 pc radius solar neighborhood, closely related to the Gould belt. The following parameters of the exponential density distribution have been determined: the average $(z_G)_\odot=-25\pm5$ pc and scale height $h_G=56\pm6$ pc. We propose a method of excluding background stars from the samples, which are located at large heights with respect to the symmetry plane of the Gould belt. We discovered that the expansion effect for the entire star system, $K_G=6\pm1$ km s$^{-1}$ kpc$^{-1}$, is determined mainly by the dynamics of the Scorpius-Centaurus association. We show that the angular velocity of the residual intrinsic rotation of the Gould belt can reach $\Omega_G=6.9\pm0.2$ km s$^{-1}$ kpc$^{-1}$ and that this rotation is opposite to the galactic rotation.