2022ApJ...926..141T -
Astrophys. J., 926, 141-141 (2022/February-3)
The 3D Kinematics of the Orion Nebula Cluster: NIRSPEC-AO Radial Velocities of the Core Population.
THEISSEN C.A., KONOPACKY Q.M., LU J.R., KIM D., ZHANG S.Y., HSU C.-C., CHU L. and WEI L.
Abstract (from CDS):
The kinematics and dynamics of stellar and substellar populations within young, still-forming clusters provide valuable information for constraining theories of formation mechanisms. Using Keck II NIRSPEC+AO data, we have measured radial velocities for 56 low-mass sources within 4' of the core of the Orion Nebula Cluster (ONC). We also remeasure radial velocities for 172 sources observed with SDSS/APOGEE. These data are combined with proper motions measured using HST ACS/WFPC2/WFC3IR and Keck II NIRC2, creating a sample of 135 sources with all three velocity components. The velocities measured are consistent with a normal distribution in all three components. We measure intrinsic velocity dispersions of (σ{vα}, σ{vδ}, σ{v{r}}) = (1.64 ± 0.12, 2.03 ± 0.13, {2.56}_{-0.17}^{+0.16}) km s–1. Our computed intrinsic velocity dispersion profiles are consistent with the dynamical equilibrium models from Da Rio et al. (2014) in the tangential direction but not in the line-of-sight direction, possibly indicating that the core of the ONC is not yet virialized, and may require a nonspherical potential to explain the observed velocity dispersion profiles. We also observe a slight elongation along the north-south direction following the filament, which has been well studied in previous literature, and an elongation in the line-of-sight to tangential velocity direction. These 3D kinematics will help in the development of realistic models of the formation and early evolution of massive clusters.
Abstract Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Stellar kinematics - Radial velocity - Star formation - Star forming regions - Open star clusters - Stellar associations
VizieR on-line data:
<Available at CDS (J/ApJ/926/141): table3.dat table5.dat>
Simbad objects:
228
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