space Paradigm Challenge

Our Sun likely went through a violent phase of massive eruptive outbursts during its early life.

April 23, 2026

Original Paper

The FUor Mass Distribution Matches the Solar Neighborhood IMF: Evidence for a Universal Eruptive Phase

Adolfo S. Carvalho, Lynne A. Hillenbrand

arXiv · 2604.19975

The Takeaway

Young stars known as FUors experience extreme brightness surges that were previously thought to be rare anomalies. New mass distribution data shows these events match the general population of stars in our solar neighborhood. This implies that the eruptive phase is a universal rite of passage for almost every star in the universe. Understanding these ancient solar tantrums helps explain how the planets in our own system were forged in a much more chaotic environment than today.

From the abstract

Eruptive accretion events are expected to play an important role in the mass buildup stage of individual star formation. FU Ori objects (FUors) experience the most extreme eruptive outbursts, which raise the accretion rate of the disk from $10^{-9}-10^{-8} \ M_\odot \ \mathrm{yr}^{-1}$ to $10^{-5}-10^{-4} \ M_\odot \ \mathrm{yr}^{-1}$ and last for decades. During an outburst, the disk is approximately 100 times brighter than the star, making direct study of the central star impossible. However,