On the Formation Age of the First Planetary System

TL;DR

This paper estimates the formation epoch of the first planetary systems in the universe, suggesting they could have formed as early as 60 million years after the Big Bang, based on cosmological density fluctuations.

Contribution

It provides a novel estimate for the formation time of the first planetary systems using Gaussian distribution of density perturbations in standard cosmology.

Findings

First planetary systems could form within 60 million years after the Big Bang.

Formation within our galaxy could occur within 170 million years.

Planets around metal-poor stars are plausible and observationally significant.

Abstract

Recently, it has been observed the extreme metal-poor stars in the Galactic halo, which must be formed just after Pop III objects. On the other hand, the first gas clouds of mass $\sim 10^6 M_{\odot}$ are supposed to be formed at $ z \sim $ 10, 20, and 30 for the $1\sigma$, $2\sigma $ and $3\sigma$, where the density perturbations are assumed of the standard $\Lambda$CDM cosmology. If we could apply this gaussian distribution to the extreme small probability, the gas clouds would be formed at $ z \sim $40, 60, and 80 for the $4\sigma$, $6\sigma$, and $8\sigma$. The first gas clouds within our galaxy must be formed around $z\sim 40$. Even if the gas cloud is metal poor, there is a lot of possibility to form the planets around such stars. The first planetary systems could be formed within $\sim 6\times 10^7$ years after the Big Bang in the universe. Even in our galaxies, it could be formed within $\sim 1.7\times 10^8$ years. It is interesting to wait the observations of planets around metal-poor stars. For the panspermia theory, the origin of life could be expected in such systems.