A&A 559, A111 (2013) Astronomy DOI: 10.1051/0004-6361/201321616 & c ESO 2013 Astrophysics An interferometric study of the post-AGB binary 89 Herculis I. Spatially resolving the continuum circumstellar environment at optical and near-IR wavelengths with the VLTI, NPOI, IOTA, PTI, and the CHARA Array,, M. Hillen1, T. Verhoelst1,2,H.VanWinckel1, O. Chesneau3,C.A.Hummel4, J. D. Monnier5, C. Farrington6, C. Tycner7, D. Mourard3, T. ten Brummelaar6,D.P.K.Banerjee8,andR.T.Zavala9 1 Instituut voor Sterrenkunde (IvS), KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium e-mail:
[email protected] 2 Belgian Institute for Space Aeronomy, 1180 Brussels, Belgium 3 Laboratoire Lagrange, UMR7293, Univ. Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, 06300 Nice, France 4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany 5 University of Michigan, 941 Dennison Building, 500 Church Street, Ann Arbor, MI 48109-1090, USA 6 The CHARA Array of Georgia State University, Mt. Wilson Observatory, Mt. Wilson, CA 91023, USA 7 Department of Physics, Central Michigan University, Mt. Pleasant, MI 48859, USA 8 Physical Research Laboratory, Navrangpura, 380009 Ahmedabad, India 9 US Naval Observatory, Flagstaff Station, 10391 W. Naval Obs. Rd., Flagstaff, AZ 86001, USA Received 1 April 2013 / Accepted 25 July 2013 ABSTRACT Context. Binary post-asymptotic giant branch (post-AGB) stars are interesting laboratories to study both the evolution of binaries as well as the structure of circumstellar disks. Aims. A multiwavelength high angular resolution study of the prototypical object 89 Herculis is performed with the aim of identifying and locating the different emission components seen in the spectral energy distribution.