Dust Continuum Imaging of the HH 24 Region in L1630

We have mapped the 1300 and 350 μm continuum emission in the region surrounding the Herbig-Haro objects HH 22-HH 26 in L1630, which is part of the Orion B molecular cloud complex, using the MPIR bolometer at the IRAM 30 m telescope and the SHARC bolometer camera at the Caltech Submillimeter Observatory (CSO). Our observations reveal the presence of a cluster of at least nine protostellar condensations at various evolutionary stages in the region around HH 24-HH 26. In addition to two previously identified class 0 protostars, two additional sources with a low 350/1300 μm flux ratio are detected. Although the lack of far-infrared fluxes precludes a definitive determination of their nature, their low 350/1300 μm flux ratio along with the absence of embedded infrared and radio continuum sources suggests that they are likely to be in a very early evolutionary stage. In particular, one of these two sources appears quite compact in the 1300 μm image and may be in the short-lived phase of isothermal collapse. In addition, we have detected three millimeter continuum sources in the vicinity of the HH 22-HH 23 objects, including a compact source at the origin of the HH 23 optical jet. The bolometric luminosity, submillimeter-to-bolometric luminosity ratio, temperature, and mass of this source are all consistent with those of a class 0 protostar. However, the compactness of the source suggests that the continuum emission may be dominated by an unresolved disk, as would be expected for a more evolved protostellar source. No evidence is found for the presence of a molecular outflow associated with this source in our CO, ¹³CO, and HCO⁺ data obtained with the CSO.