The local star formation history of the thin disc derived from kinematic data

TL;DR

This paper develops a self-consistent evolutionary model of the thin disc in the solar neighborhood, revealing a declining star formation rate over the past 10 Gyr and detailing the vertical structure and kinematics of stellar populations.

Contribution

It introduces a new dynamical model combining star formation history and stellar heating, fitting velocity data to derive the disc's evolution and structure.

Findings

Star formation peaked 10 Gyr ago and declined steadily.

Velocity dispersion increases with age following a power law.

The derived IMF has a continuous power-law without a kink around 1 Msun.

Abstract

We present an evolutionary disc model for the thin disc in the solar cylinder based on a continuous star formation history and a continuous dynamical heating of the stellar subpopulations. The vertical distribution of the stellar subpopulations are calculated self-consistently in dynamical equilibrium. The SFR and AVR of the stellar subpopulations are determined by fitting the velocity distribution functions of main sequence stars. The SFR shows a maximum 10 Gyr ago declining by a factor of 10 until present time. A constant SFR can be ruled out. The velocity dispersion of the stellar subpopulations increase with age according to a power law with index 0.375. The new scale heights lead to a best fit IMF with power-law indices of 1.5 below and 4.0 above 1.6 Msun, which has no kink around 1 Msun. Including a thick disc component results in slight variations of the thin disc properties, but has a negligible influence on the SFR. A variety of predictions are made concerning the number density, age and metallicity distributions of stellar subpopulations as a function of z above the galactic plane.