Thermal Jeans fragmentation within 1000 AU in OMC-1S

Palau, Aina; Zapata, Luis A.; Roman-Zuniga, Carlos G.; Sanchez-Monge, Alvaro; Estalella, Robert; Busquet, Gemma; Girart, Josep M.; Fuente, Asuncion; Commercon, Benoit
eprint arXiv:1706.04623


We present subarcsecond 1.3 mm continuum ALMA observations towards the Orion Molecular Cloud 1 South (OMC-1S) region, down to a spatial resolution of 100 AU. The observations reveal a total of 31 continuum sources, which are grouped in cores along three main filaments, with the cores being separated about 2000 AU in the filaments. We also present subarcsecond 7 mm continuum VLA observations of the same region, which allow to further study fragmentation in each core down to a spatial resolution of 40 AU. Typical separations between fragments are <560 AU and about 2900 AU, suggesting a two-level fragmentation process. In addition, a higher fragmentation level is clearly found towards the southern filament, which is the one enclosing a higher mass (higher density) within 1000 AU per each fragmenting core. This is fully consistent with previous studies of fragmentation at spatial scales one order of magnitude larger, and suggests that fragmentation down to 40 AU seems to be governed by thermal Jeans processes in OMC-1S.