Binary Formation in a 100 μm Dark Massive Core

doi:10.3847/1538-4357/acd252

Binary Formation in a 100 μm Dark Massive Core

2023-06-26

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DOI：10.3847/1538-4357/acd252

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We report high-resolution ALMA observations toward a massive protostellar core C1-Sa (& SIM;30 M (& ODOT;)) in the Dragon infrared dark cloud. At the resolution of 140 au, the core fragments into two kernels (C1-Sa1 and C1-Sa2) with a projected separation of & SIM;1400 au along the elongation of C1-Sa, consistent with a Jeans length scale of & SIM;1100 au. Radiative transfer modeling using RADEX indicates that the protostellar kernel C1-Sa1 has a temperature of & SIM;75 K and a mass of 0.55 M (& ODOT;). C1-Sa1 also likely drives two bipolar outflows, one being parallel to the plane of the sky. C1-Sa2 is not detected in line emission and does not show any outflow activity but exhibits ortho-H2D+ and N2D+ emission in its vicinity; thus it is likely still starless. Assuming a 20 K temperature, C1-Sa2 has a mass of 1.6 M (& ODOT;). At a higher resolution of 96 au, C1-Sa1 begins to show an irregular shape at the periphery, but no clear sign of multiple objects or disks. We suspect that C1-Sa1 hosts a tight binary with inclined disks and outflows. Currently, one member of the binary is actively accreting while the accretion in the other is significantly reduced. C1-Sa2 shows hints of fragmentation into two subkernels with similar masses, which requires further confirmation with higher sensitivity.

Keywords:

STAR-FORMING REGIONS

TRIGONOMETRIC PARALLAXES

MAGNETIC-FIELDS

OUTFLOW

CLOUD

PROGRAM

ORTHO-H2D+

DYNAMICS

ORIGIN

CLUMPS

Binary Formation in a 100 μm Dark Massive Core

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