Volume 553, May 2013
|Number of page(s)||8|
|Section||Celestial mechanics and astrometry|
|Published online||17 May 2013|
Trigonometric parallaxes of massive star forming regions: G012.88+0.48 and W33
Max-Planck-Institut für Radioastronomie,
Auf dem Hügel 69,
2 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, 02140 Cambridge, MA, USA
Received: 26 November 2012
Accepted: 25 March 2013
We report trigonometric parallaxes for water masers in the G012.88+0.48 region and in the massive star forming complex W33 (containing G012.68−0.18, G012.81−0.19, G012.90−0.24, G012.90−0.26), from the Bar and Spiral Structure Legacy (BeSSeL) survey using the Very Long Baseline Array. The parallax distances to all these masers are consistent with kpc, which locates the W33 complex and G012.88+0.48 in the Scutum spiral arm. Our results show that W33 is a single star forming complex at about two-thirds the kinematic distance of 3.7 kpc. The luminosity and mass of this region, based on the kinematic distance, have therefore been overestimated by more than a factor of two. The spectral types in the star cluster in W33 Main have to be changed by 1.5 points to later types.
Key words: astrometry / masers / parallaxes / proper motions / stars: distances / stars: formation
© ESO, 2013
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