VLTI-AMBER Observations of η Carinae with
High Spatial Resolution and Spectral
Resolutions of λ/Δλ = 1500 and 12000
G. Weigelt, S. Kraus, T. Driebe, K.-H. Hofmann, F. Millour,
R. Petrov, D. Schertl, O. Chesneau, K. Davidson, A. Domiciano de
Souza, T. Gull, J.D. Hillier, F. Malbet, F. Rantakyrö, A. Richichi,
M. Schöller, and M. Wittkowski
ESO workshop "Science with the VLT in the ELT Era"
held in Garching (Germany) on 8-12 October 2007
Astrophysics and Space Science Proceedings
"Science with the VLT in the ELT Era", pg.107-111 (2009)
Abstract
We report spectro-interferometric observations of the Luminous Blue Variable
(LBV) η Car using the AMBER instrument of ESO's Very Large Telescope
Interferometer (VLTI) [1]. The observations around the He I 2.059
µm and the
Brγ 2.166 µm emission lines allow us to investigate the wavelength dependence
of the visibility, differential phase, and closure phase of η Car's stellar wind
region. If we fit visibility profiles derived from Hillier et al. models [2] to the
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. For the interpretation of the non-zero differential and closure
phases measured within the Brγ line, we developed a simple wind model. Our
observations support theoretical models of winds from fast-rotating, luminous
hot stars.
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