The Nature of the Gould Belt from a Fractal Analysis of its Stellar Population

TL;DR

This study investigates the fractal structure of the Gould Belt's stellar population, revealing differences in spatial distribution between young and older stars, which sheds light on its formation and evolution.

Contribution

The paper introduces a tailored fractal dimension estimation algorithm and applies it to analyze the spatial structure of stars in the Gould Belt, providing new insights into its nature.

Findings

Young OB stars in the GB have a fractal dimension similar to gas clouds.

Older stars in the GB show a fractal dimension akin to the local Galactic disk.

Younger stars preserve the spatial memory of their birth clouds.

Abstract

The Gould Belt (GB) is a system of gas and young, bright stars distributed along a plane that is inclined with respect to the main plane of the Milky Way. Observational evidence suggests that the GB is our closest star formation complex, but its true nature and origin remain rather controversial. In this work we analyze the fractal structure of the stellar component of the GB. In order to do this, we tailor and apply an algorithm that estimates the fractal dimension in a precise and accurate way, avoiding both boundary and small data set problems. We find that early OB stars (of spectral types earlier than B4) in the GB have a fractal dimension very similar to that of the gas clouds in our Galaxy. On the contrary, stars in the GB of later spectral types show a larger fractal dimension, similar to that found for OB stars of both age groups in the local Galactic disk (LGD). This result seems to indicate that while the younger OB stars in the GB preserve the memory of the spatial structure of the cloud where they were born, older stars are distributed following a similar morphology as that found for the LGD stars. The possible causes for these differences are discussed.