Dynamical mass of the O-type supergiant in ζ Orionis A

  title={Dynamical mass of the O-type supergiant in $\zeta$ Orionis A},
  author={Christian A. Hummel and Th. Rivinius and M. Fernanda Nieva and Otmar Stahl and Gerard T. van Belle and Robert T. Zavala},
  journal={Astronomy and Astrophysics},
Aims. A close companion ofζ Orionis A was found in 2000 with the Navy Precision Optical Interferometer (NPOI), and shown to be a physical companion. Because the primary is a supergiant of type O, for which dynamical mass measurements are very rare, the companion was observed with NPOI over the full 7-year orbit. Our aim was to determine the dynamical mass of a supergiant that, due to the physical separation of more than 10 AU between the components, cannot have undergone mass exchange with the… 

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