Binary Formation in a 100 μm Dark Massive Core

We report high-resolution ALMA observations toward a massive protostellar core C1-Sa ($\sim$30 M$_\odot$) in the Dragon Infrared Dark Cloud. At resolution of 140 AU, fragments into two kernels (C1-Sa1 and C1-Sa2) with projected separation $\sim$1400 AU along elongation C1-Sa, consistent Jeans length scale $\sim$1100 AU. Radiative transfer modeling using RADEX indicates that kernel C1-Sa1 has temperature $\sim$75 K mass 0.55 M$_\odot$. also likely drives bipolar outflows, one being parallel to plane-of-the-sky. C1-Sa2 is not detected line emission does show any outflow activity but exhibits ortho-H$_2$D$^+$ N$_2$D$^+$ its vicinity, thus it still starless. Assuming 20 temperature, 1.6 higher 96 begins an irregular shape at periphery, no clear sign multiple objects or disks. suspect hosts tight binary inclined disks outflows. Currently, member actively accreting while accretion other significantly reduced. shows hints fragmentation sub-kernels similar masses, which requires further confirmation sensitivity.