TY - GEN
T1 - VLTI-AMBER observations of Eta Carinae with high spatial resolution and spectral resolutions of 1,500 and 10,000
AU - Weigelt, Gerd
AU - Petrov, Romain G.
AU - Chesneau, Olivier
AU - Davidson, Kris
AU - De Souza, Armando Domiciano
AU - Driebe, Thomas
AU - Foy, Renaud
AU - Fraix-Burnet, Didier
AU - Gull, Ted
AU - Hillier, John D.
AU - Hofmann, Karl Heinz
AU - Kraus, Stefan
AU - Malbet, Fabien
AU - Marconi, Alessandro
AU - Mathias, Philippe
AU - Monin, Jean Louis
AU - Millour, Florentin
AU - Ohnaka, Keiichi
AU - Rantakyrö, Frederik
AU - Richichi, Andrea
AU - Schertl, Dieter
AU - Schöller, Markus
AU - Stee, Philippe
AU - Testi, Leonardo
AU - Wittkowski, Markus
PY - 2006
Y1 - 2006
N2 - We present the first interferometric NIR observations of the LEV 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 Brγ emission 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.
AB - We present the first interferometric NIR observations of the LEV 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 Brγ emission 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.
KW - Infrared: stars
KW - Stars: individual: η Carinae
KW - Stars: mass-loss, emission-line, circumstellar matter, winds, outflows
KW - Techniques: interferometric, high angular resolution, spectroscopic
UR - http://www.scopus.com/inward/record.url?scp=33749265623&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33749265623&partnerID=8YFLogxK
U2 - 10.1117/12.671582
DO - 10.1117/12.671582
M3 - Conference contribution
AN - SCOPUS:33749265623
SN - 0819463337
SN - 9780819463333
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Advances in Stellar Interferometry
T2 - Advances in Stellar Interferometry
Y2 - 25 May 2006 through 30 May 2006
ER -