Radio jet in the H II region Orion B

Abstract

An arcmin-resolution image is presented of the nearby H IIregion Orion B (NGC 2024, W12) made in the radio continuum at a frequency of 330 MHz. The image displays a spectacular jet-like feature extending northwards and up to 10 arcmin from the core of the nebula. The radio jet is parallel to a molecular bipolar flow seen in the associated molecular cloud. Continuum radio emission is also detected to the south of the H II region and positionally coincident with the southern molecular jet. Despite the large optical depth, the imaging shows surface-brightness variations in the main body of the H II region. The brightness temperature towards the peak of the continuum emission directly measures the electron temperature of the ionized gas to be 8400 ± 1000 K.