Measuring Turbulence with Young Stars in the Orion Complex

Monday 28 Mar 2022, 14:10 → 14:30 Europe/Rome

0/0-3 - Sala Rosino (Dipartimento di Fisica e Astronomia - Edificio ex-Rizzato)

Speakers: Anastasiia Plotnikova (Università degli Studi di Padova)

Stars form in molecular clouds in the interstellar medium (ISM) with a turbulent kinematic state. Newborn stars therefore should retain the turbulent kinematics of their natal clouds. Gaia DR2 andAPOGEE-2 surveys in combination provide three-dimensional (3D) positions and 3D velocities ofyoung stars in the Orion Molecular Cloud Complex. Using the full 6D measurements, we compute thevelocity structure functions (VSFs) of the stars in six different groups within the Orion Complex. Wefind that the motions of stars in all diffuse groups exhibit strong characteristics of turbulence. Theirfirst-order VSFs have a power-law exponent ranging from∼0.2−0.5 on scales of a few to a few tensof pc, generally consistent with Larson’s relation. On the other hand, dense star clusters, such as theOrion Nebula Cluster (ONC), have experienced rapid dynamical relaxation, and have lost the memoryof the initial turbulent kinematics. The VSFs of several individual groups and the whole Complex allshow features supporting local energy injection from supernovae. The measured strength of turbulencedepends on the location relative to the supernova epicenters and the formation history of the groups.Our detection of turbulence traced by young stars introduces a new method of probing the turbulentkinematics of the ISM. Unlike previous gas-based studies with only projected measurements accessibleto observations, we utilize the full 6D information of stars, presenting a more complete picture of the3D interstellar turbulence.

2101.03176.pdf

JC schedule

zoom