Weigelt, G., Hofmann, K. -H., Schertl, D., Clementel, N., Corcoran, M. F., Damineli, A., de Wit, W. -J., Grellmann, R., Groh, J., Guieu, S., Gull, T., Heininger, M., Hillier, D. J., Hummel, C. A., Kraus, S., Madura, T., Mehner, A., Merand, A., Millour, F., Moffat, A. F. J., Ohnaka, K., Patru, F., Petrov, R. G., Rengaswamy, S., Richardson, N. D., Rivinius, T., Schoeller, M., Teodoro, M. and Wittkowski, M. (2016). 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 zone. Astron. Astrophys., 594. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. The 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 eta Car's primary star wind and wind-wind collision zone with a high spatial resolution of similar to 6 mas (similar to 14 au) and high spectral resolution of R = 12000. Methods. Observations of eta 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 different spectral channels distributed across the Br gamma 2.166 mu m 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(-1) measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of 277 km s(-1), the position angle of the symmetry axis of the fan is similar to 126 degrees. The fan-shaped structure extends approximately 8.0 mas (similar to 18.8 au) to the southeast and 5.8 mas (similar to 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.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Weigelt, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hofmann, K. -H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schertl, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Clementel, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Corcoran, M. F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Damineli, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
de Wit, W. -J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Grellmann, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Groh, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Guieu, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gull, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Heininger, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hillier, D. J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Hummel, C. A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kraus, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Madura, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Mehner, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Merand, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Millour, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Moffat, A. F. J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Ohnaka, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Patru, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Petrov, R. G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rengaswamy, S.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Richardson, N. D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Rivinius, T.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schoeller, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Teodoro, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wittkowski, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-258904
DOI: 10.1051/0004-6361/201628832
Journal or Publication Title: Astron. Astrophys.
Volume: 594
Date: 2016
Publisher: EDP SCIENCES S A
Place of Publication: LES ULIS CEDEX A
ISSN: 1432-0746
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
RADIATIVE-TRANSFER SIMULATIONS; 2014.6 SPECTROSCOPIC EVENT; 1ST OVERTONE LINES; LONG-PERIOD BINARY; COLLIDING WINDS; HOMUNCULUS-NEBULA; STELLAR WIND; LIGHT-CURVE; DYNAMICAL ATMOSPHERE; IONIZATION STRUCTUREMultiple languages
Astronomy & AstrophysicsMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/25890

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