A VLBA Survey of radio stars in the Orion Nebula Cluster: II. Astrometry

Abstract

From Very Long Baseline Array (VLBA) observations we previously identified a population of 123 young stellar systems with nonthermal radio emission toward the core of the Orion Nebula Cluster (ONC). We find optical sources in the Gaia DR2 catalog for 34 of them within 0.2" of the radio positions. Most of the radio sources are likely companions of Gaia detections. However, there are 11 stars whose VLBA position differs from Gaia by $<1.6$ mas, and some of these radio sources probably are the direct counterparts of the optical stars. We are able to obtain radio proper motions for 23 stars. Combining the stellar proper motions derived from the VLBA and Gaia data we find the global motion and velocity dispersion of the ONC to be (${\mu }_{\alpha }\ast ,{\mu }_{\delta }$)=($1.20\pm 0.09,0.18\pm 0.09$) mas yr${}^{-1}$ and (${\sigma }_{{\mu }_{\alpha }\ast },{\sigma }_{{\mu }_{\delta }}$)=($0.84\pm 0.09,1.30\pm 0.09$) mas yr${}^{-1}$. Finally, we looked for ordered motions by estimating the means of scalar and vectorial products, which results in $\overline{\mathbf{v}\cdot \hat{\mathbf{r}}}=-0.61\pm 1.00$ km s${}^{-1}$ and $\overline{\mathbf{v}\times \hat{\mathbf{r}}}=0.57\pm 0.95$ km s${}^{-1}$. These do not show indications that the young stellar cluster is in expansion, contraction, or rotation.

Accepted for publication in ApJ. 16 pages, 4 figures, 7 tables

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Cited by in corpus (9)

• A VLBA Survey of radio stars in the Orion Nebula Cluster: I. The nonthermal radio population
• Non-thermal radio continuum emission from young nearby stars
• A systematic survey of millimetre-wavelength flaring variability of Young Stellar Objects in the Orion Nebula Cluster
• From downtown to the outskirts: a radio survey of the Orion Nebula Cluster
• Link between the Optical and Radio Frames from Gaia DR3 Data and VLBI Measurements
• Dynamical masses of YSOs with the VLBA: DYNAMO VLBA: Trigonometric parallaxes and proper motions of YSOs in Orion
• VLBI detection of nearby (< 100 pc) young stars: Pilot observations
• Dynamical masses of young stellar objects with the VLBA: DYNAMO-VLBA: Radio binary stars in Orion
• The population of compact radio sources in M 17