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arXiv · 0901.0517

A Precise Distance to IRAS 00420+5530 via H2O Maser Parallax with the VLBA

G. A. Moellenbrock·M. J. Claussen·W. M. Goss
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Abstract

We have used the VLBA to measure the annual parallax of the H2O masers in the star-forming region IRAS 00420+5530. This measurement yields a direct distance estimate of 2.17 +/- 0.05 kpc (<3%), which disagrees substantially with the standard kinematic distance estimate of ~4.6 kpc (according to the rotation curve of Brand and Blitz 1993), as well as most of the broad range of distances (1.7-7.7 kpc) used in various astrophysical analyses in the literature. The 3-dimensional space velocity of IRAS 00420+5530 at this new, more accurate distance implies a substantial non-circular and anomalously slow Galactic orbit, consistent with similar observations of W3(OH) (Xu et al., 2006; Hachisuka et al. 2006), as well as line-of-sight velocity residuals in the rotation curve analysis of Brand and Blitz (1993). The Perseus spiral arm of the Galaxy is thus more than a factor of two closer than previously presumed, and exhibits motions substantially at odds with axisymmetric models of the rotating Galaxy.

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G. A. Moellenbrock, M. J. Claussen, W. M. Goss. 2009-01-05. A Precise Distance to IRAS 00420+5530 via H2O Maser Parallax with the VLBA. https://doi.org/10.1088/0004-637x%2F694%2F1%2F192

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