28 July 2008 VLTI-AMBER observations of Eta Carinae with the FINITO fringe tracker and spectral resolution 12000
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We present interferometric near-infrared observations of the Luminous Blue Variable (LBV) η Car using the Very Large Telescope Interferometer (VLTI) and the AMBER instrument of the European Southern Observatory (ESO). A high spatial resolution of 5 mas (~11.5 AU) and a high spectral resolution R = λ/Δλ=1500 and 12000 were obtained. Some of the data was recorded using the fringe tracker FINITO. The observations were obtained in the wavelength range around both the He I 2.059 μm and the Brγ 2.166 μm emission lines. The AMBER interferograms allow the investigation of the wavelength dependence of η Car's visibility, wavelength-differential phase, and closure phase. If we fit Hillier et al. model visibilities to the observations, we obtain 50% encircled-energy diameters of 4.2, 6.5 and 9.6 mas in the 2.17 μm continuum, the He I, and the Brγ emission lines, respectively. In the continuum, an elongation along a position angle of 120° ± 15° was derived from the visibilities. The VLTI observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the pole.
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Gerd Weigelt, Gerd Weigelt, Olivier Chesneau, Olivier Chesneau, Thomas Driebe, Thomas Driebe, Renaud Foy, Renaud Foy, Didier Fraix-Burnet, Didier Fraix-Burnet, Jose H. Groh, Jose H. Groh, Karl-Heinz Hofmann, Karl-Heinz Hofmann, Stefan Kraus, Stefan Kraus, Fabien Malbet, Fabien Malbet, Alessandro Marconi, Alessandro Marconi, Philippe Mathias, Philippe Mathias, Florentin Millour, Florentin Millour, Jean-Louis Monin, Jean-Louis Monin, Romain G. Petrov, Romain G. Petrov, Frederik Rantakyrö, Frederik Rantakyrö, Andrea Richichi, Andrea Richichi, Dieter Schertl, Dieter Schertl, Markus Schöller, Markus Schöller, Philippe Stee, Philippe Stee, Leonardo Testi, Leonardo Testi, Markus Wittkowski, Markus Wittkowski, } "VLTI-AMBER observations of Eta Carinae with the FINITO fringe tracker and spectral resolution 12000", Proc. SPIE 7013, Optical and Infrared Interferometry, 701303 (28 July 2008); doi: 10.1117/12.796204; https://doi.org/10.1117/12.796204

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