A NEAR-INFRARED REFLECTION NEBULA ASSOCIATED WITH NGC 2024 FIR 4

摘要

H, K, and 3.6 μm imaging observations at the location of the protostellar candidate NGC 2024 FIR 4 confirm the presence of a highly reddened near-infrared source with estimated luminosity ～25 solar luminosity at the position of the submillimeter continuum core. Polarimetry at H and K shows that this source is accompanied by a compact cometary reflection nebula of the type associated with collimated molecular outflows from young stellar objects. These results enable the classification of NGC 2024 FIR 4 as a low-mass, self-luminous, young stellar object producing an energetic outflow which is beginning to clear the ambient dense gas. The details of the observed polarization vector pattern at H and K suggest the superposition of an extended polarization field which distorts the scattering pattern in the reflection nebula from centrosymmetry. It is likely that this additional field is produced by dichroic absorption through a foreground screen of dust grains aligned by an ordered magnetic field with projected orientation close to P.A. = 0°.