Dynamical masses of young stellar objects with the VLBA: DYNAMO-VLBA: Trigonometric parallaxes and proper motions of YSOs in Orion

Abstract

We present results from a multi-epoch Very Long Baseline Array (VLBA) survey of compact radio sources in the Orion complex, conducted within both the DYNAMO–VLBA and GOBELINS projects. We detected 216 compact radio sources, of which 58 yielded reliable multi-epoch astrometric solutions. For these sources, we derived trigonometric parallaxes and proper motions with typical precisions of about 0.05 mas and 0.10 mas yr−1, respectively. The measured parallaxes range between 2.26 and 2.65 mas, corresponding to distances of 380–440 pc, and delineate the depth of the Orion star-forming complex. We determined mean distances of 405 ± 16 pc for NGC 2068, 403 ± 5 pc for NGC 2024, 407 ± 12 pc for the σ Orionis region, 388.5 ± 1.7 pc for the Orion Nebula Cluster, and 438 ± 12 pc for L1641. A comparison with Gaia DR3 astrometry for 28 common sources revealed negligible mean parallax offsets (Δϖ= − 0.02 ± 0.01 mas) and small systematic differences in proper motions (∼0.07 mas yr−1), likely due to the residual rotation of the Gaia reference frame. Our results demonstrate the capability of high-precision radio astrometry to map embedded stellar populations and to provide an independent calibration of the Gaia reference system in obscured regions.