VLTI-AMBER velocity-resolved aperture-synthesis imaging of Eta Car's wind-wind collision zone
Gerd Weigelt  1, *@  , Karl-Heinz Hofmann  1@  , Dieter Schertl  1@  , Nicola Clementel  2@  , Michael Corcoran  3@  , Augusto Damineli  4@  , Willem-Jan De Wit  5@  , Rebekka Grellmann  6@  , Jose Groh  7@  , Sylvain Guieu  5@  , Ted Gull  8@  , Kenji Hamaguchi  9@  , Matthias Heininger  1@  , Desmond Hillier  10, *@  , Christian Hummel  11@  , Stefan Kraus  12@  , Tom Madura  13@  , Andrea Mehner  5@  , Antoine Merand  11@  , Florentin Millour  14@  , Anthony Moffat  15@  , Keiichi Ohnaka  16@  , Fabien Patru  17@  , Romain Petrov  14@  , Sridharan Rengaswamy  18@  , Noel Richardson  19@  , Thomas Rivinius  5@  , Markus Schöller  11@  , Mairan Teodoro  8@  , Markus Wittkowski  11@  
1 : Max Planck Institute for Radio Astronomy
2 : South African Astronomical Observatory
3 : CRESST and X-ray Astrophysics Laboratory, Goddard Space Flight Center; Universities Space Research Association
4 : Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo
5 : European Southern Observatory
6 : I. Physikalisches Institut, Universität zu Köln
7 : School of Physics, Trinity College Dublin, The University of Dublin
8 : Astrophysics Science Division, Goddard Space Flight Center
9 : CRESST and X-ray Astrophysics Laboratory, NASA/GSFC; Department of Physics, University of Maryland
10 : Department of Physics and Astronomy & Pittsburgh Particle Physics, Astrophysics, and Cosmology Center (PITT PACC), University of Pittsburgh
11 : European Southern Observatory
12 : University of Exeter, Astrophysics Group
13 : Department of Physics and Astronomy, San Jose State University
14 : Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d'Azur
CNRS : UMR7293
15 : Département de physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal
16 : Universidad Católica del Norte, Instituto de Astronomía, Chile
17 : Osservatorio Astrofisico di Arcetri
18 : Indian Institute of Astrophysics
19 : Ritter Observatory, Department of Physics and Astronomy, The University of Toledo
* : Corresponding author

Eta Car is a unique object for studying the massive stellar winds in a wind-collision binary during the LBV phase. X-ray studies show that there is a phase-dependent wind collision zone in Eta Car. We present velocity-resolved Eta Car images reconstructed in more than 100 different spectral channels distributed across the Brackett Gamma emission line. Interferometry can provide information on the orbit, the primary wind, and the wind collision. The obtained images of Eta Car's primary star wind and wind collision zone have a spatial resolution of 6 mas (14 au) and high spectral resolution of 12000. For example, at wavelengths corresponding to radial velocities of -140 to -376 km/s, the intensity distribution has a fan-shaped structure. The fan extends 8.0 mas (19 au) to the southeast and 5.8 mas (14 au) to the northwest. The shapes of the velocity-resolved intensity distributions suggest that the obtained images are the first images of the innermost wind collision zone. Therefore, the observations provide time- and velocity-dependent image structures that can be used to test 3-D hydrodynamical models of the massive interacting winds of Eta Car.


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