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We report ALMA and VLA continuum observations that potentially identify thefour youngest protostars in the Orion Molecular Clouds taken as part of theOrion VANDAM program. These are distinguished by bright, extended, irregularemission at 0.87 mm and 8 mm and are optically thick at 0.87 mm. Thesestructures are distinct from the disk or point-like morphologies seen towardthe other Orion protostars. The 0.87 mm emission implies temperatures of 41-170K, requiring internal heating. The bright 8 mm emission implies masses of 0.5to 1.2 M_sun assuming standard dust opacity models. One source has a Class 0companion, while another exhibits substructure indicating acompanion-candidate. Three compact outflows are detected, two of which may bedriven by companions, with dynamical times of ~300 to ~400 years. The slowestoutflow may be driven by a first hydrostatic core. These protostars appear totrace an early phase when the centers of collapsing fragments become opticallythick to their own radiation and compression raises the gas temperature. Thisphase is thought to accompany the formation of hydrostatic cores. A keyquestion is whether these structures are evolving on free fall times of ~100years, or whether they are evolving on Kelvin-Helmholtz times of severalthousand years. The number of these sources imply a lifetime of ~6000 years, incloser agreement with the Kelvin-Helmholtz time. In this case, rotationaland/or magnetic support could be slowing the collapse.

Detection of Irregular, Sub-mm Opaque Structures in the Orion Molecular Clouds: Protostars within 10000 years of formation?