Preprint

Keck Interferometer Observations of FU Orionis Objects

R. Millan‐GabetMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125Rachel AkesonDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090Charles BeichmanMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125J. P. BergerHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138Billmeier, RLaboratoire d’Astrophysique de Grenoble, 414 rue de la Piscine, 38400 Saint Martin d’Heres, FranceA. F. BodenDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090A. J. BoothUlugh Beg Astronomical Institute, Tashkent 700052, UzbekistanNuria CalvetDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109-1090M. M. ColavitaHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138Creech-Eakman, M JUniversidad Nacional Autónoma de MéxicoPaola D’AlessioDepartment of Astronomy, California Institute of Technology, Pasadena, CAJ. GathrightPrinceton University, Princeton, NJLee HartmannHarvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138Lynne A. HillenbrandDepartment of Physics, University of SydneyM. HrynevychMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125C. KoreskoMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125Kuchner, MJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Le Mignant, DJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Ligon, RJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Melnikov, S YuW. M. Keck Observatory, California Association for Research in Astronomy, Kamuela, HI 96743Mennesson, BW. M. Keck Observatory, California Association for Research in Astronomy, Kamuela, HI 96743Monnier, J DMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125Neyman, CW. M. Keck Observatory, California Association for Research in Astronomy, Kamuela, HI 96743Sargent, AJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Shao, MJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Swain, MW. M. Keck Observatory, California Association for Research in Astronomy, Kamuela, HI 96743Tannirkulam, ADepartment of Astronomy, California Institute of Technology, Pasadena, CAThompson, RJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Traub, W ALaboratoire d’Astrophysique de Grenoble, 414 rue de la Piscine, 38400 Saint Martin d’Heres, FranceTuthill, P GMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125Unwin, SJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Van Belle, G TMichelson Science Center, California Institute of Technology, Mail Stop 100-22, Pasadena, CA 91125Vasisht, GJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109Wizinowich, PW. M. Keck Observatory, California Association for Research in Astronomy, Kamuela, HI 96743

2005en

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Annotatsiya

We present new K-band long baseline interferometer observations of three young stellar objects of the FU Orionis class, V1057 Cyg, V1515 Cyg and Z CMa-SE, obtained at the Keck Interferometer during its commissioning science period. The interferometer clearly resolves the source of near-infrared emission in all three objects. Using simple geometrical models we derive size scales (0.5-4.5 AU) for this emission. All three objects appear significantly more resolved than expected from simple models of accretion disks tuned to fit the broadband optical and infrared spectro-photometry. We explore variations in the key parameters that are able to lower the predicted visibility amplitudes to the measured levels, and conclude that accretion disks alone do not reproduce the spectral energy distributions and K-band visibilities simultaneously. We conclude that either disk models are inadequate to describe the near-infrared emission, or additional source components are needed. We hypothesize that large scale emission (10s of AU) in the interferometer field of view is responsible for the surprisingly low visibilities. This emission may arise in scattering by large envelopes believed to surround these objects.

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