SMA imaging of protostars within the northern OMC-1 filaments

We report Submillimeter Array (SMA) 1.3mm observations of the OMC1 northern filaments (previously identified from SCUBA JCMT 850 micron continuum and VLA ammonia observations). We find 24 compact sources along an extent of ~3' within the filaments. The sources range in mass from 0.5 to 2.8 MSun and 3 of them are driving CO molecular outflows. The millimeter emission may be arising from the inner part of the envelope and circumstellar disk; these compact sources are therefore in the Class 0/I evolutionary phase. The spatial analysis of the protostars shows that these are divided into small groups that are separated by a quasi-equidistant length of 30' (0.06pc), consistent with the Jeans length, and therefore indicating the filament underwent thermal fragmentation. Within the protostellar groups, the typical separation is ~7'' (2800au). The protostars within OMC-1n show similar masses and sizes to those in OMC2/3, however their spatial separations are distinctly different and may point to how fragmentation propagated through the integral-shaped filament in Orion A.