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VLTI-AMBER Velocity-Resolved Aperture-Synthesis Imaging of Eta Carinae with a Spectral Resolution of 12 000: Studies of the Primary Star Wind and Innermost Wind-Wind Collision ZoneThe mass loss from massive stars is not understood well. Eta Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Aims. We want to investigate the structure and kinematics of Car's primary star wind and wind-wind collision zone with a high spatial resolution of approx.6 mas (approx.14 au) and high spectral resolution of R = 12 000. Methods. Observations of Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision. Results. We present velocity-resolved aperture-synthesis images reconstructed in more than 100 di erent spectral channels distributed across the Br(gamma) 2.166 micron emission line. The intensity distribution of the images strongly depends on wavelength. At wavelengths corresponding to radial velocities of approximately -140 to -376 km/s measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of -277 km/s, the position angle of the symmetry axis of the fan is 126. The fan-shaped structure extends approximately 8.0 mas (approx.18:8 au) to the southeast and 5.8 mas (approx.13:6 au) to the northwest, measured along the symmetry axis at the 16% intensity contour. The shape of the intensity distributions suggests that the obtained images are the first direct images of the innermost wind-wind collision zone. Therefore, the observations provide velocity-dependent image structures that can be used to test three-dimensional hydrodynamical, radiative transfer models of the massive interacting winds of Eta Car.
Document ID
20160013719
Document Type
Reprint (Version printed in journal)
Authors
Weigelt, G. (Max-Planck-Inst. fuer Radioastronomie Bonn, Germany)
Hofmann, K.-H. (Max-Planck-Inst. fuer Radioastronomie Bonn, Germany)
Schertl, D. (Max-Planck-Inst. fuer Radioastronomie Bonn, Germany)
Clementel, N. (South African Astronomical Observatory Cape Town, South Africa)
Corcoran, M. F. (Universities Space Research Association Columbia, MD, United States)
Damineli, A. (Sao Paulo Univ. Brazil)
de Wit, W.-J. (European Southern Observatory Santiago, Chile)
Grellmann, R. (Cologne Univ. Germany)
Groh, J. (Trinity Coll. Dublin, Ireland)
Guieu, S. (European Southern Observatory Santiago, Chile)
Gull, T. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Heininger, M. (Max-Planck-Inst. fuer Radioastronomie Bonn, Germany)
Hillier, D. J. (Pittsburgh Univ. Pittsburgh, PA, United States)
Hummel, C. A. (European Southern Observatory Garching, Germany)
Kraus, S. (Exeter Univ. United Kingdom)
Madura, T. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Mehner, A. (European Southern Observatory Santiago, Chile)
Merand, A. (European Southern Observatory Santiago, Chile)
Millour, F. (Universite de Nice-Sophia Antipolis Valbonne, France)
Moffat, A. F. J. (Montreal Univ. Quebec, Canada)
Ohnaka, K. (Universidad Catolica del Norte Coquimbo, Chile)
Patru, F. (Osservatorio Astrofisico Arcetri Florence, Italy)
Petrov, R. G. (Universite de Nice-Sophia Antipolis Valbonne, France)
Rengaswamy, S. (Indian Inst. of Astrophysics Bangalore, India)
Richardson, N. D. (Toledo Univ. Toledo, OH, United States)
Rivinius, T. (European Southern Observatory Santiago, Chile)
Schoeller, M. (European Southern Observatory Garching, Germany)
Teodoro, M. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Wittkowski, M. (European Southern Observatory Garching, Germany)
Date Acquired
November 22, 2016
Publication Date
October 19, 2016
Publication Information
Publication: Astronomy & Astrophysics
Volume: 594
Subject Category
Astrophysics
Astronomy
Report/Patent Number
GSFC-E-DAA-TN37476
Funding Number(s)
CONTRACT_GRANT: NNG06EO90A
Distribution Limits
Public
Copyright
Other
Keywords
Velocity-resolved aperture-synthesis images
ESO Very Large Telescope Interferometer (VLTI)
Eta Carinae