A dense micro-cluster of Class 0 protostars in NGC 2264D-MM1

We present sensitive and high angular resolution (∼ 1′′) 1.3 mm continuum observations of the dusty core D-MM1 in the Spokes cluster in NGC 2264 using the Submillimeter Array. A dense micro-cluster of seven Class 0 sources was detected in a 20′′× 20′′ region with masses between 0.4 to 1.2 M and deconvolved sizes of about 600 AU. We interpret the 1.3 mm emission as arising from the envelopes of the Class 0 protostellar sources. The mean separation of the 11 known sources (SMA Class 0 and previously known infrared sources) within D-MM1 is considerably smaller than the characteristic spacing between sources in the larger Spokes cluster and is consistent with hierarchical thermal fragmentation of the dense molecular gas in this region. Subject headings: stars: formation – stars: circumstellar matter – stars: planetary systems: protoplanetary disks – techniques: interferometric