Astronomers mapped the three-dimensional orbital motion of the massive protobinary system IRAS 07299−1651, finding that its two stars formed via a near-parabolic encounter between distinct cores, Nature Astronomy reported. The observations provide direct orbital measurements during the earliest embedded phase of massive star formation.
The researchers found that the two protostellar components currently sit at a separation of approximately 200 astronomical units. Orbital fitting showed that the preferred trajectories are highly eccentric and close to parabolic. Both circumstellar disks show substantial misalignment with the orbital plane. These orbital characteristics indicate that the two protostars originated independently from initially unbound cores that experienced a recent flyby, rather than emerging from a single fragmented disk.
The collaboration gathered high-resolution submillimetre-to-centimetre data from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (JVLA). Infrared images from the James Webb Space Telescope (JWST) and the Very Large Telescope (VLT) supplemented the radio measurements. Researchers combined continuum modelling, hydrogen recombination line kinematics, and jet observations to constrain the physical geometry of the binary.
Scientists reduced the ALMA and JVLA datasets using CASA version 6.6.4 and cleaned 1/f noise from JWST imaging with a dedicated Python script. The team fitted radio interferometric visibilities using UVMultiFit version 3.1 and modeled hydrogen recombination line spectra with lmfit version 1.3.2.
Investigators generated model orbits with the open-source packages orbitize! version 3.1.0 and pyorb version 0.6.0. Posterior distributions were sampled with emcee version 3.1.6, and chain convergence was evaluated using ArviZ version 0.17.1. Reduced continuum images and spectral cubes for IRAS 07299−1651 were deposited in the Zenodo public repository under DOI 10.5281/zenodo.20913729.
