Near-Infrared Imaging Polarimetry of M42: Aperture Polarimetry of Point-like Sources

Abstract

We have conducted aperture polarimetry of ~500 stars of the Orion Nebula Cluster (ONC) in M42 based on our wide-field (~8'\times 8') $JHKs$ band polarimetry. Most of the near-infrared (NIR) polarizations are dichroic, with position angles of polarization agreeing, both globally and locally, with previous far-infrared (FIR) and submillimeter observations, having taken into account the 90${}^{\circ }$ difference in angles between dichroic absorption and emission. This is consistent with the idea that both NIR dichroic polarizations and FIR/submillimeter thermal polarizations trace the magnetic fields in the OMC-1 region. The magnetic fields inferred from these observations show a pinch at scales less than 0.5 pc with a centroid near IRc2. The hourglass-shaped magnetic field pattern is explained by the models in which the magnetic field lines are dragged along with the contracting gas and then wound up by rotation in a disk. The highly polarized region to the northwest of IRc2 and the low-polarized region near the bright bar are also common among NIR and FIR/submillimeter data, although a few regions of discrepancy exist. We have also discerned ~50 possible highly polarized sources whose polarizations are more likely to be intrinsic rather than dichroic. Their polarization efficiencies ($P(H)/A(H)$) are too large to be explained by the interstellar polarization. These include 10 young brown dwarfs that suggest a higher polarization efficiency, which may present geometrical evidence for (unresolved) circumstellar structures around young brown dwarfs.

arXiv comment40 pages, 10 figures, H band polarization data table

References in corpus (15)

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• The Spectroscopically Determined Substellar Mass Function of the Orion Nebula Cluster
• Evidence for a T Tauri Phase in Young Brown Dwarfs
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• High Resolution Millimeter-Wave Mapping of Linearly Polarized Dust Emission: Magnetic Field Structure in Orion
• Tracing the Magnetic Field in Orion A
• Thermal Conduction in Magnetized Turbulent Gas
• The Structure of Brown Dwarf Circumstellar Disks
• SCUBA polarisation observations of the magnetic fields in the prestellar cores L1498 and L1517B
• Gold alignment & internal dissipation
• First Two-Micron Imaging Polarimetry of Beta Pictoris
• Near Infrared Polarization Images of the Orion Nebula
• Hubble Space Telescope NICMOS Polarization Measurements of OMC-1
• An optical spectroscopic H-R diagram for low-mass stars and brown dwarfs in Orion
• Polarization of Thermal Emission from Aligned Dust Grains Under an Anisotropic Radiation Field

Cited by in corpus (15)

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• Near-Infrared Imaging Polarimetry of the Serpens Cloud Core: Magnetic Field Structure, Outflows, and Inflows in A Cluster Forming Clump
• Near-IR Imaging Polarimetry toward a Bright-Rimmed Cloud: Magnetic Field in SFO 74
• Near-infrared Linear Polarization of Ultracool Dwarfs
• Optical/Near-IR Polarization Survey of Sh 2-29: Magnetic Fields, Dense Cloud Fragmentations and Anomalous Dust Grain Sizes
• Linear polarization of rapidly rotating ultracool dwarfs
• Near-Infrared Circular Polarimetry and Correlation Diagrams in the Orion BN/KL Region: Contribution of Dichroic Extinction
• Near Infrared polarimetry of a sample of YSOs
• Distortion of Magnetic Fields in a Starless Core III: Polarization--Extinction Relationship in FeSt 1-457
• Multi-Scale Analysis of Magnetic Fields in Filamentary Molecular Clouds in Orion A
• Near-Infrared Imaging Polarimetry of S106 Cluster-Forming Region with SIRPOL
• Distortion of Magnetic Fields in a Starless Core V: Near-infrared and Submillimeter Polarization in FeSt 1-457
• Near-Infrared Polarimetric Study of N159/N160 Star-Forming Complex in the Large Magellanic Cloud