2024/01/29 by Guang-Xing Li, Li, Guang-Xing
Physics and Astronomy · #Astro and Planetary Science #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2401.16083
openalex publication_date 2024/01/29 · openalex created_date 2024/01/31 · openalex updated_date 2026/07/28
The Jeans criterion is one cornerstone in our understanding of gravitational fragmentation. A critical limitation of the Jeans criterion is that the background density is assumed to be a constant, which is often not true in dynamic conditions such as star-forming regions. For example, during the formation phase of the high-density gas filaments in a molecular cloud, a density increase rate ρ implies a mass accumulation time of t\rm acc= ρ/ ρ= - ρ(∇ ⋅ (ρv))-1. The system is non-stationary when the mass accumulation time becomes comparable to the free-fall time t\rm ff = 1 / √(G ρ). We study fragmentation in non-stationary settings, and find that accretion can significantly increase in the characteristic mass of gravitational fragmentation ( λ\rm Jeans, aac= λ\rm Jeans (1 + t\rm ff / t\rm acc)1/3, m\rm Jeans, acc = m\rm Jeans (1 + t\rm ff / t\rm acc)). In massive star-forming regions, this mechanism of transport-driven super-jeans fragmentation can contribute to the formation of massive stars by causing order-of-magnitude increases in the mass of the fragments.