Orbital and mass constraints of the young binary system IRAS 16293-2422 A

Abstract

We present 3 mm ALMA continuum and line observations at resolutions of 6.5 au and 13 au respectively, toward the Class 0 system IRAS 16293-2422 A. The continuum observations reveal two compact sources towards IRAS 16293-2422 A, coinciding with compact ionized gas emission previously observed at radio wavelengths (A1 and A2), confirming the long-known radio sources as protostellar. The emission towards A2 is resolved and traces a dust disk with a FWHM size of ~12 au, while the emission towards A1 sets a limit to the FWHM size of the dust disk of ~4 au. We also detect spatially resolved molecular kinematic tracers near the protostellar disks. Several lines of the J=5-4 rotational transition of HNCO, NH2CHO and t-HCOOH are detected, with which we derived individual line-of-sight velocities. Using these together with the CS (J=2-1), we fit Keplerian profiles towards the individual compact sources and derive masses of the central protostars. The kinematic analysis indicates that A1 and A2 are a bound binary system. Using this new context for the previous 30 years of VLA observations, we fit orbital parameters to the relative motion between A1 and A2 and find the combined protostellar mass derived from the orbit is consistent with the masses derived from the gas kinematics. Both estimations indicate masses consistently higher (0.5< M1<M2<2 Msun) than previous estimations using lower resolution observations of the gas kinematics. The ALMA high-resolution data provides a unique insight into the gas kinematics and masses of a young deeply embedded bound binary system.

Accepted for publication in ApJ. 23 pages, 14 figures, 4 tables

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• Dust hot spots at 10 au scales around the Class 0 binary IRAS 16293-2422 A: a departure from the passive irradiation model
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• Constraints on the (re-)orientation of star-disk systems through infall
• Implementation of Rare Isotopologues into Machine Learning of the Chemical Inventory of the Solar-Type Protostellar Source IRAS 16293-2422
• A deep search for large complex organic species toward IRAS16293-2422 B at 3 mm with ALMA
• PRODIGE -- Envelope to Disk with NOEMA III. The origin of complex organic molecule emission in SVS13A
• On the frequencies of circumbinary discs in protostellar systems
• The molecular environment of the solar-type protostar IRAS 16293-2422
• Filling in the Gaps: Can Gravitationally Unstable Discs Form the Seeds of Gas Giant Planets?
• ALMA ACA study of the H${}_2$S/OCS ratio in low-mass protostars
• Assessing realistic binding energies of some essential interstellar radicals with amorphous solid water. A fully quantum chemical approach
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• A 16 au Binary in the Class 0 Protostar L1157 MMS
• Physicochemical models: source-tailored or generic?
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• FAUST. XXVIII. High-Resolution ALMA Observations of Class 0/I Disks: Structure, Optical Depths, and Temperatures
• FAUST XXV. A potential new molecular outflow in [BHB2007] 11
• Misaligned Circumstellar Disks and Orbital Motion of the Young Binary XZ Tau
• Role of NH3 Binding Energy in the Early Evolution of Protostellar Cores
• Exploring the 100 au Scale Structure of the Protobinary System NGC 2264 CMM3 with ALMA
• An Eccentric Massive Protobinary Assembled via a Core-merger Parabolic Encounter
• Carbon chain diversity in L1544 and IRAS 16293-2422: an astrochemical pathfinder study for the SKAO
• Rotating Motion of the Outflow of IRAS 16293-2422 A1 at its Origin Point near the Protostar