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Proceedings Paper

VLTI-AMBER observations of Eta Carinae with high spatial resolution and spectral resolutions of 1,500 and 10,000
Author(s): Gerd Weigelt; Romain G. Petrov; Olivier Chesneau; Kris Davidson; Armando Domiciano de Souza; Thomas Driebe; Renaud Foy; Didier Fraix-Burnet; Ted Gull; John D. Hillier; Karl-Heinz Hofmann; Stefan Kraus; Fabien Malbet; Alessandro Marconi; Philippe Mathias; Jean-Louis Monin; Florentin Millour; Keiichi Ohnaka; Frederik Rantakyrö; Andrea Richichi; Dieter Schertl; Markus Schöller; Philippe Stee; Leonardo Testi; Markus Wittkowski
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Paper Abstract

We present the first interferometric NIR observations of the LBV η Carinae with high spectral resolution. The observations were carried out with three 8.2 m VLTI Unit Telescopes in the K-band. The raw data are spectrally dispersed interferograms obtained with spectral resolutions of 1,500 (MR-K mode) and 12,000 (HR-K mode). The observations were performed in the wavelength range around both the He I 2.059 μm and the Brγ 2.166 μm emission lines. The spectrally dispersed AMBER interferograms allow the investigation of the wavelength dependence of the visibility, differential phase, and closure phase of η Car. In the K-band continuum, a diameter of 4.0±0.2 mas (Gaussian FWHM) was measured for η Car's optically thick wind region, whereas the Brγ and He I emission line regions are larger. If we fit Hillier et al. model visibilities to the observed AMBER visibilities, we obtain 50% encircled-energy diameters of 4.3, 6.5 and 9.6 mas in the 2.17 μm continuum, the He I, and the Brγemission lines, respectively. In the continuum near the Brγ line, an elongation along a position angle of 128° ± 15° was found, consistent with previous VLTI/VINCI measurements. We find good agreement between the measured visibilities and the predictions of the radiative transfer model of Hillier et al. For the interpretation of the non-zero differential and closure phases measured within the Brγ line, we present a simple geometric model of an inclined, latitude-dependent wind zone. Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions.

Paper Details

Date Published: 28 June 2006
PDF: 6 pages
Proc. SPIE 6268, Advances in Stellar Interferometry, 62682S (28 June 2006); doi: 10.1117/12.671582
Show Author Affiliations
Gerd Weigelt, Max-Planck-Institut für Radioastronomie (Germany)
Romain G. Petrov, Lab. Univ. d'Astrophysique de Nice, Univ. de Nice/CNRS (France)
Olivier Chesneau, Lab. Gemini, Observatoire de la Côte d'Azur/CNRS (France)
Kris Davidson, Univ. of Minnesota (United States)
Armando Domiciano de Souza, Lab. Gemini, Observatoire de la Côte d'Azur/CNRS (France)
Lab. Univ. d'Astrophysique de Nice, Univ. de Nice/CNRS (France)
Thomas Driebe, Max-Planck-Institut für Radioastronomie (Germany)
Renaud Foy, Ctr. de Recherche Astronomique de Lyon, Univ. Claude Bernard/CNRS (France)
Didier Fraix-Burnet, Lab. d'Astrophysique de Grenoble, Univ. Joseph Fourier/CNRS (France)
Ted Gull, NASA Goddard Space Flight Ctr. (United States)
John D. Hillier, Univ. of Pittsburgh (United States)
Karl-Heinz Hofmann, Max-Planck-Institut für Radioastronomie (Germany)
Stefan Kraus, Max-Planck-Institut für Radioastronomie (Germany)
Fabien Malbet, Lab. d'Astrophysique de Grenoble, Univ. Joseph Fourier/CNRS (France)
Alessandro Marconi, INAF-Osservatorio Astrofisico di Arcetri (Italy)
Philippe Mathias, Lab. Gemini, Observatoire de la Côte d'Azur/CNRS (France)
Jean-Louis Monin, Lab. d'Astrophysique de Grenoble, Univ. Joseph Fourier/CNRS (France)
Florentin Millour, Lab. d'Astrophysique de Grenoble, Univ. Joseph Fourier/CNRS (France)
Lab. Univ. d'Astrophysique de Nice, Univ. de Nice/CNRS (France)
Keiichi Ohnaka, Max-Planck-Institut für Radioastronomie (Germany)
Frederik Rantakyrö, European Southern Observatory (Chile)
Andrea Richichi, European Southern Observatory (Germany)
Dieter Schertl, Max-Planck-Institut für Radioastronomie (Germany)
Markus Schöller, European Southern Observatory (Chile)
Philippe Stee, Lab. Gemini, Observatoire de la Côte d'Azur/CNRS (France)
Leonardo Testi, INAF-Osservatorio Astrofisico di Arcetri (Italy)
Markus Wittkowski, European Southern Observatory (Chile)


Published in SPIE Proceedings Vol. 6268:
Advances in Stellar Interferometry
John D. Monnier; Markus Schöller; William C. Danchi, Editor(s)

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