History of Globulettes in the Milky Way

TL;DR

This study estimates the number of globulettes in the Milky Way and their potential contribution to free-floating planets, suggesting they could be a significant source of such objects.

Contribution

It provides the first large-scale estimate of globulettes in the Milky Way and their possible role in forming free-floating planets.

Findings

Approximately 5.7×10^{10} globulettes formed in the Milky Way.

If 10% form free-floating planets, they could account for 5.7×10^{9} such planets.

Globulettes could contribute up to 2.0×10^{10} free-floating planets.

Abstract

Globulettes are small (radii $< 10$ kAU) dark dust clouds, seen against the background of bright nebulae. A majority of the objects have planetary mass. These objects may be a source of brown dwarfs and free floating planetary mass objects in the galaxy. In this paper we investigate how many globulettes could have formed in the Milky Way and how they could contribute to the total population of free floating planets. In order to do that we examine H-alpha images of 27 H~II regions. In these images, we find 778 globulettes. We find that a conservative value of the number of globulettes formed is $5.7\times 10^{10}$. If 10 \% of the globulettes form free floating planets then they have contributed with $5.7\times 10^{9}$ free floating planets in the Milky Way. A less conservative number of globulettes would mean that the globulettes could contribute $2.0\times 10^{10}$ free floating planets. Thus the globulettes could represent a non-negligible source of free floating planets in the Milky Way.