Mid-Infrared and Submillimeter Observations of the Illuminating Source of McNeil's Variable Nebula

Abstract

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 micron 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_sun, and is likely less than 90 L_sun. The mid-infrared spectrum exhibits a strong and red continuum with no emission or absorption features. The infrared slope of the spectral energy distribution characterizes the illuminating source as a flat-spectrum protostar, in both its active and quiescent states. New CO spectral line observations show no evidence for a molecular outflow.