Accurate proper motions of the protostellar system VLA1623-2417

Ricardo Hernández Garnica; Laurent Loinard; Carlos Carrasco-González; Jazmín Ordóñez-Toro; Johanan Ramírez-Arellano; María José Maureira; Isaac C. Radley; Eleonora Bianchi; Claire J. Chandler; Luis F. Rodríguez; Rosa M. Torres; Aina Palau

arXiv · 2607.14428

Accurate proper motions of the protostellar system VLA1623-2417

Ricardo Hernández Garnica·Laurent Loinard·Carlos Carrasco-González·Jazmín Ordóñez-Toro·Johanan Ramírez-Arellano·María José Maureira·Isaac C. Radley·Eleonora Bianchi·Claire J. Chandler·Luis F. Rodríguez·Rosa M. Torres·Aina Palau

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Abstract

We present a detailed astrometric analysis of the quadruple protostellar system VLA1623-2417, deriving accurate absolute proper motions for components A, B, and W, as well as, for the first time, individual motions for the compact binary components of A (Aa and Ab). Our study combines 37 archival interferometric observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very Large Array (VLA) at centimeter and millimeter wavelengths, supplemented with additional data from the Submillimeter Array (SMA) and the Berkeley-Illinois-Maryland Association (BIMA) millimeter array taken from the literature. Together, these data provides time baselines of ~34.5 years for component B, ~32.5 years for component W, and ~11 years for the individual components Aa and Ab. The relative proper motions of Aa/Ab indicate significant orbital motions, but cover too small a fraction of the orbit to provide a reliable mass estimate. The relative proper motions of W with respect to components A and B indicate that their projected separations are decreasing at a rate of 1 to 2 km/s. These inward motions are inconsistent with scenarios in which component W has been dynamically ejected from the VLA1623-2417 system. Instead, we argue that W is either not bound to the A/B components or is moving on a highly inclined orbit.

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Ricardo Hernández Garnica, Laurent Loinard, Carlos Carrasco-González, Jazmín Ordóñez-Toro, Johanan Ramírez-Arellano, María José Maureira, Isaac C. Radley, Eleonora Bianchi, Claire J. Chandler, Luis F. Rodríguez, Rosa M. Torres, Aina Palau. 2026-07-15. Accurate proper motions of the protostellar system VLA1623-2417. https://arxiv.org/abs/2607.14428

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