Mid-Infrared and Submillimeter Observations of the Illuminating Source of MCNeil’s Variable Nebula

We present post-outburst observations of the mid-infrared spectrum and submillimeter continuum of the illuminating source of the newly discovered McNeil's Nebula in the L1630 region of Orion. The 12 μm flux of this source has increased by a factor of ~25 after the outburst, whereas the submillimeter continuum remains at its pre-outburst level. The bolometric luminosity has increased by at least an order of magnitude, to ~34 L☉, and is likely less than 90 L☉. The mid-infrared spectrum exhibits a strong and red continuum with no emission or absorption features. The infrared slope of the spectral energy distribution identifies the illuminating source as a flat-spectrum protostar, in both its active and quiescent states. New CO spectral line observations show no evidence of a molecular outflow.