High Resolution Images of Orbital Motion in the Orion Trapezium Cluster with the LBT Adaptive Optics System

Abstract

The new 8.4m LBT adaptive secondary AO system, with its novel pyramid wavefront sensor, was used to produce very high Strehl (75% at 2.16 microns) near infrared narrowband (Br gamma: 2.16 microns and [FeII]: 1.64 microns) images of 47 young (~1 Myr) Orion Trapezium theta1 Ori cluster members. The inner ~41x53" of the cluster was imaged at spatial resolutions of ~0.050" (at 1.64 microns). A combination of high spatial resolution and high S/N yielded relative binary positions to ~0.5 mas accuracies. Including previous speckle data, we analyse a 15 year baseline of high-resolution observations of this cluster. We are now sensitive to relative proper motions of just ~0.3 mas/yr (0.6 km/s at 450 pc) this is a ~7x improvement in orbital velocity accuracy compared to previous efforts. We now detect clear orbital motions in the theta1 Ori B2/B3 system of 4.9+/-0.3 km/s and 7.2+/-0.8 km/s in the theta1 Ori A1/A2 system (with correlations of PA vs. time at >99% confidence). All five members of the theta1 Ori B system appear likely as a gravitationally bound "mini-cluster". The very lowest mass member of the theta1 Ori B system (B4; mass ~0.2 Msun) has, for the first time, a clearly detected motion (at 4.3+/-2.0 km/s; correlation=99.7%) w.r.t B1. However, B4 is most likely in an long-term unstable (non-hierarchical) orbit and may "soon" be ejected from this "mini-cluster". This "ejection" process could play a major role in the formation of low mass stars and brown dwarfs.

arXiv comment27 pages, 14 figures, accepted for publication by the Astrophysical Journal

References in corpus (21)

• Modelling Accretion in Protobinary Systems
• The Formation of Brown Dwarfs as Ejected Stellar Embryos
• Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation
• New Neighbors from 2MASS: Activity and Kinematics at the Bottom of the Main Sequence
• Stellar, Brown Dwarf, and Multiple Star Properties from Hydrodynamical Simulations of Star Cluster Formation
• Binarity in Brown Dwarfs: T Dwarf Binaries Discovered with the Hubble Space Telescope WPFC2
• Analysis of isoplanatic high resolution stellar fields by Starfinder code
• The Formation Mechanism of Brown Dwarfs
• Detection of Nine M8.0-L0.5 Binaries: The Very Low Mass Binary Population and its Implications for Brown Dwarf and VLM Star Formation
• Constraints on the Stellar/Sub-stellar Mass Function in the Inner Orion Nebula Cluster
• Multiplicity of Nearby Free-floating Ultra-cool Dwarfs: a HST-WFPC2 search for companions
• A search for L dwarf binary systems
• Binary Stars in the Orion Nebula Cluster
• Visual/infrared interferometry of Orion Trapezium stars: Preliminary dynamical orbit and aperture synthesis imaging of the Theta 1 Orionis C system
• Thermal Infrared MMTAO Observations of the HR 8799 Planetary System
• Large Binocular Telescope Adaptive Optics System: New achievements and perspectives in adaptive optics
• New Photometry and Spectra of AB Doradus C: An Accurate Mass Determination of a Young Low-Mass Object with Theoretical Evolutionary Tracks
• The evolution of binary populations in cool, clumpy star clusters
• A Near-Infrared Wide-Field Proper Motion Search for Brown Dwarfs
• Eccentricity generation in hierarchical triple systems with coplanar and initially circular orbits
• High Resolution Images of Orbital Motion in the Trapezium Cluster: First Scientific Results from the MMT Deformable Secondary Mirror Adaptive Optics System

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