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Water maser motions in W3(OH) and a determination of its distance

K. Hachisuka·A. Brunthaler·K. M. Menten·M. J. Reid·H. Imai·Y. Hagiwara·M. Miyoshi·S. Horiuchi·T. Sasao
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Abstract

We report phase-referencing VLBA observations of H2O masers near the star-forming region W3(OH) to measure their parallax and absolute proper motions. The measured annual parallax is 0.489 +/- 0.017 milli-arcseconds (2.04 +/- 0.07 kpc), where the error is dominated by a systematic atmospheric contribution. This distance is consistent with photometric distances from previous observations and with the distance determined from CH3OH maser astrometry presented in a related paper. We also find that the source driving the H2O outflow, the ``TW-object'', moves with a 3-dimensional velocity of > 7 km/s relative to the ultracompact HII region W3(OH).

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K. Hachisuka, A. Brunthaler, K. M. Menten, M. J. Reid, H. Imai, Y. Hagiwara, M. Miyoshi, S. Horiuchi, T. Sasao. 2006-01-25. Water maser motions in W3(OH) and a determination of its distance. https://doi.org/10.1086/502962

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