A VLA Survey of Orion Class 0 Protostars at 30 AU Resolution

We present initial results from the VANDAM:Orion survey, a VLA survey of Class 0 protostars in Orion. Disks and multiple systems are thought to originate early in the star formation process, when the protostars are deeply embedded in dense envelopes. The VANDAM survey of the Perseus molecular cloud demonstrated that VLA Ka-band (33 GHz) observations can resolve disks and companions around Class 0 protostars, providing the means to study the incidence and separations of companions, and the properties of disks during the first 100,000 years of protostellar evolution. The VANDAM:Orion survey targets 92 Class 0 protostars in the Orion Molecular clouds, the largest population of Class 0 objects within 500 pc of the Sun. These were selected from protostars characterized by the Herschel Orion Protostar Survey, or HOPS, which assembled 1.6-870 micron SEDs of 319 protostars in the Orion A and B molecular clouds. VANDAM:Orion not only triples the number of Class 0 protostars observed with the VLA , as compared to the original VANDAM survey, but also samples the diverse environments found in the Orion clouds. VANDAM:Orion also includes 38 Class I protostars found near the targeted Class 0 objects.VANDAM:Orion initially carried out VLA observations in the C-array to determine their fluxes in the Ka-band (33 GHZ). The subsequent A-array observations then imaged the protostars with a resolution of 0.08”/34 AU. The entire sample has now been observed and reduced. We will overview the detection statistics and show examples of multiple systems and disks around Orion Class 0 protostars. The VLA images will also be compared to images from a recent ALMA 850 micron snapshot survey of all Orion protostars characterized by HOPS. Many sources appear opaque to ALMA at 870 μm, but the dust is optically thin for the VLA, enabling it to detect structure that ALMA cannot. Finally, we will discuss the prospects of VANDAM:Orion for characterizing the role of environment in the formation of multiple systems and disks.Support for this work was provided by the NSF through a Student Observing Support award for proposal VLA 16A-197 from the NRAO.