• DOI:10.1088/0004-637X/749/2/180
• Corpus ID: 119298839

High-resolution Images of Orbital Motion in the Orion Trapezium Cluster with the LBT AO System

@article{Close2012HighresolutionIO,
  title={High-resolution Images of Orbital Motion in the Orion Trapezium Cluster with the LBT AO System},
  author={Laird M. Close and Alfio T. Puglisi and Jared R. Males and Carmelo Arcidiacono and Andrew J. I. Skemer and Juan Carlos Guerra and Lorenzo Busoni and Guido Brusa and Enrico Pinna and D. L. Miller and Armando Riccardi and Diane McCarthy and Marco Xompero and Craig Kulesa and Fernando Quir{\'o}s-Pacheco and Javier Argomedo and Joar G. Brynnel and Simone Esposito and Filippo Mannucci and K. Boutsia and Luca Fini and D. J. Thompson and J M Hill and Charles E. Woodward and Runa Briguglio and Timothy J. Rodigas and Paolo Stefanini and Guido Agapito and Philip M. Hinz and Katherine B. Follette and Robert Green},
  journal={The Astrophysical Journal},
  year={2012},
  volume={749},
  pages={180}
}

• L. Close, A. Puglisi, +28 authors R. Green
• Published 12 March 2012
• Physics
• The Astrophysical Journal

The new 8.4 m LBT adaptive secondary AO system, with its novel pyramid wavefront sensor, was used to produce very high Strehl ({approx}> 75% at 2.16 {mu}m) near-infrared narrowband (Br{gamma}: 2.16 {mu}m and [Fe II]: 1.64 {mu}m) images of 47 young ({approx}1 Myr) Orion Trapezium {theta}{sup 1} Ori cluster members. The inner {approx}41 Multiplication-Sign 53'' of the cluster was imaged at spatial resolutions of {approx}0.''050 (at 1.64 {mu}m). A combination of high spatial resolution and high S/N yielded relative binary positions to {approx}0.5 mas accuracies. Including previous speckle data, we analyze a 15 year baseline of high-resolution observations of this cluster. We are now sensitive to relative proper motions of just {approx}0.3 mas yr{sup -1} (0.6 km s{sup -1} at 450 pc); this is a {approx}7 Multiplication-Sign improvement in orbital velocity accuracy compared to previous efforts. We now detect clear orbital motions in the {theta}{sup 1} Ori B{sub 2} B{sub 3} system of 4.9 {+-} 0.3 km s{sup -1} and 7.2 {+-} 0.8 km s{sup -1} in the {theta}{sup 1} Ori A{sub 1} A{sub 2} system (with correlations of P.A. versus time at >99% confidence). All five members of the {theta}{sup 1} Ori B system appear likely a gravitationally boundmore » 'mini-cluster'. The very lowest mass member of the {theta}{sup 1} Ori B system (B{sub 4}; mass {approx}0.2 M{sub Sun }) has, for the first time, a clearly detected motion (at 4.3 {+-} 2.0 km s{sup -1}; correlation = 99.7%) w.r.t. B{sub 1}. However, B{sub 4} is most likely in a 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.« less