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arXiv · 2512.13136

VLBI astrometry of radio stars to link radio and optical celestial reference frames - II. 11 radio stars

Jingdong Zhang·Bo Zhang·Shuangjing Xu·Xiaofeng Mai·Mark J. Reid·Pengfei Jiang·Wen Chen·Fengchun Shu·Jinling Li·Lang Cui·Xingwu Zheng·Yan Sun·Zhaoxiang Qi
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Abstract

The alignment between the radio-based International Celestial Reference Frame (ICRF) and the optical Gaia Celestial Reference Frame (Gaia-CRF) is critical for multi-waveband astronomy, yet systematic offsets at the optical bright end (G<13) limit their consistency. While radio stars offer a potential link between these frames, their utility has been restricted by the scarcity of precise Very Long Baseline Interferometry (VLBI) astrometry. In this study, we present new VLBI astrometry of 11 radio stars using the Very Long Baseline Array (VLBA), expanding the existing sample with positions, parallaxes, and proper motions measured. All 11 radio stars were detected, for 10 of which parallaxes and proper motions can be estimated, achieving median uncertainties better than 0.1 mas and 0.1 mas/yr, respectively. These new samples greatly contribute to the link between ICRF and Gaia-CRF at the optical bright end.

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Jingdong Zhang, Bo Zhang, Shuangjing Xu, Xiaofeng Mai, Mark J. Reid, Pengfei Jiang, Wen Chen, Fengchun Shu, Jinling Li, Lang Cui, Xingwu Zheng, Yan Sun, Zhaoxiang Qi. 2025-12-15. VLBI astrometry of radio stars to link radio and optical celestial reference frames - II. 11 radio stars. https://doi.org/10.1093/mnras%2Fstag244

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