2022.02.03 - Javier Ballesteros
Channel: Coloquio IRyA
Date: 09/02/2022

Speaker info: Dr. Javier Ballesteros, Investigador, IRyA-UNAM
https://www.irya.unam.mx/web/en/people/research-staff/j-ballesteros

Title: Gravity or turbulence? Gaia observations through Orion
Abstract:
Two models of molecular cloud dynamics are in the literature. On one hand, the “turbulent” one, where MCs are supported by turbulence over several free-fall times. On the other hand, the “hierarchical and chaotic global collapse” one, which states that as MCs form, they collapse, form stars and disperse, all within a few free-fall times. In this one,  the non-thermal motions that people interpret as turbulence are generated by the collapse itself, but they are hardly a mechanism that supports clouds. 
    
Both models of MCs reproduce important observational features of MCs. Using Gaia EDR3, we have found what appears to be a distinctive feature that may allow us to disentangle which model of cloud formation and evolution is at play in MCs: the velocity dispersion of the newborn stars as a function of the mass of the stars. While turbulence models show that massive stars rapidly acquire high velocity dispersion, collapsing models show the distinctive signs of violent relaxation, where the velocity dispersion does not depend on the mass bin of the stars.