Weigelt, G. and Hofmann, K.-H. and Schertl, D. and Lopez, B. and Petrov, R. G. and Lagarde, S. and Berio, Ph. and Jaffe, W. and Henning, Th. and Millour, F. and Meilland, A. and Allouche, F. and Robbe-Dubois, S. and Matter, A. and Cruzalèbes, P. and Hillier, D. J. and Russell, C. M. P. and Madura, T. and Gull, T. R. and Corcoran, M. F. and Damineli, A. and Moffat, A. F. J. and Morris, P. W. and Richardson, N. D. and Paladini, C. and Schöller, M. and Mérand, A. and Glindemann, A. and Beckmann, U. and Heininger, M. and Bettonvil, F. and Zins, G. and Woillez, J. and Bristow, P. and Sanchez-Bermudez, J. and Ohnaka, K. and Kraus, S. and Mehner, A. and Wittkowski, M. and Hummel, C. A. and Stee, P. and Vakili, F. and Hartman, H. and Navarete, F. and Hamaguchi, K. and Espinoza-Galeas, D. A. and Stevens, I. R. and van Boekel, R. and Wolf, S. and Hogerheijde, M. R. and Dominik, C. and Augereau, J.-C. and Pantin, E. and Waters, L. B. F. M. and Meisenheimer, K. and Varga, J. and Klarmann, L. and Gámez Rosas, V. and Burtscher, L. and Leftley, J. and Isbell, J. W. and Hocdé, V. and Yoffe, G. and Kokoulina, E. and Hron, J. and Groh, J. and Kreplin, A. and Rivinius, Th. and de Wit, W.-J. and Danchi, W.-C. and Domiciano de Souza, A. and Drevon, J. and Labadie, L. and Connot, C. and Nußbaum, E. and Lehmitz, M. and Antonelli, P. and Graser, U. and Leinert, C. (2021) VLTI-MATISSE chromatic aperture-synthesis imaging of η Carinae’s stellar wind across the Brα line. Periastron passage observations in February 2020. Astronomy and Astrophysics, 652 . Art. No. A140. ISSN 0004-6361. doi:10.1051/0004-6361/202141240. https://resolver.caltech.edu/CaltechAUTHORS:20210930-174141797
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Abstract
Context. Eta Carinae is a highly eccentric, massive binary system (semimajor axis ~15.5 au) with powerful stellar winds and a phase-dependent wind-wind collision (WWC) zone. The primary star, η Car A, is a luminous blue variable (LBV); the secondary, η Car B, is a Wolf-Rayet or O star with a faster but less dense wind. Aperture-synthesis imaging allows us to study the mass loss from the enigmatic LBV η Car. Understanding LBVs is a crucial step toward improving our knowledge about massive stars and their evolution. Aims. Our aim is to study the intensity distribution and kinematics of η Car’s WWC zone. Methods. Using the VLTI-MATISSE mid-infrared interferometry instrument, we perform Brα imaging of η Car’s distorted wind. Results. We present the first VLTI-MATISSE aperture-synthesis images of η Car A’s stellar windin several spectral channels distributed across the Brα 4.052 μm line (spectral resolving power R ~ 960). Our observations were performed close to periastron passage in February 2020 (orbital phase ~ 14.0022). The reconstructed iso-velocity images show the dependence of the primary stellar wind on wavelength or line-of-sight (LOS) velocity with a spatial resolution of 6 mas (~14 au). The radius of the faintest outer wind regions is ~26 mas (~60 au). At several negative LOS velocities, the primary stellar wind is less extended to the northwest than in other directions. This asymmetry is most likely caused by the WWC. Therefore, we see both the velocity field of the undisturbed primary wind and the WWC cavity. In continuum spectral channels, the primary star wind is more compact than in line channels. A fit of the observed continuum visibilities with the visibilities of a stellar wind CMFGEN model (CMFGEN is an atmosphere code developed to model the spectra of a variety of objects) provides a full width at half maximum fit diameter of the primary stellar wind of 2.84 ± 0.06 mas (6.54 ± 0.14 au). We comparethe derived intensity distributions with the CMFGEN stellar wind model and hydrodynamic WWC models.
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| Additional Information: | © G. Weigelt et al. 2021. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Open Access funding provided by Max Planck Society. Received 3 May 2021; Accepted 30 June 2021; Published online 25 August 2021. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 0104.D-0015A, 0104.D-0015B, 0104.D-0015C, 0106.D-0309(A), 0106.D-0309(B), and 0106.D-0309(C). MATISSE was designed, funded and built in close collaboration with ESO, by a consortium composed of institutes in France (J.-L. Lagrange Laboratory – INSU-CNRS – Côte d’Azur Observatory – University of Côte d’Azur), Germany (MPIA, MPIfR and University of Kiel), the Netherlands (NOVA and University of Leiden), and Austria (University of Vienna). We thank all ESO colleagues for the excellent collaboration. This work has been supported by the French government through the UCAJEDI Investments in the Future project managed by the National research Agency (ANR) with the reference number ANR-15-IDEX-01. The Konkoly Observatory and Cologne University have also provided some support in the manufacture of the instrument. K.O. acknowledges the support of the Agencia Nacional de Investigación y Desarrollo (ANID) through the FONDECYT Regular grant 1 180066. S.K. and A.K. acknowledge support from an STFC Consolidated Grant (ST/V000721/1) and ERC Starting Grant (Grant Agreement No. 639889). The research of J.V. and M.H. is supported by NOVA, the Netherlands Research School for Astronomy. T.H. acknowledges support from the European Research Council under the Horizon 2020 Framework Program via the ERC Advanced Grant Origins 83 24 28. A.G. acknowledges support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 695099 (project CepBin). P.A. acknowledges support from the Hungarian NKFIH OTKA grant K132406, and from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 716155 (SACCRED). A.F.J.M. is grateful for financial aid from NSERC (Canada) and FQRNT (Quebec). J.S.B. acknowledges the support received from the UNAM PAPIIT project IA 101220 and from the CONACyT project 263975. N.D.R. acknowledges some support from HST-GO programs 15611 and 15992. C.M.P.R. acknowledges support from NASA grants with Chandra award number GO0-21006A and NICER award numbers 80NSSC19K1451 and 80NSSC19K1459. A.D. thanks support from FAPESP #2019/02029-2. F.N. acknowledges FAPESP for support through proc. 2017/18191-8. This research has made use of the services of the ESO Science Archive Facility. This publication makes use of the SIMBAD database operated at CDS, Strasbourg, France. We thank the referee for helpful suggestions. | ||||||||||||||||||||||||||||||||||||||||||||||||
| Group: | Infrared Processing and Analysis Center (IPAC) | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Subject Keywords: | stars: winds, outflows – stars: individual: η Carinae – stars: massive – stars: mass-loss – binaries: general – techniques: interferometric | ||||||||||||||||||||||||||||||||||||||||||||||||
| DOI: | 10.1051/0004-6361/202141240 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Record Number: | CaltechAUTHORS:20210930-174141797 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20210930-174141797 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Official Citation: | VLTI-MATISSE chromatic aperture-synthesis imaging of η Carinae’s stellar wind across the Brα line - Periastron passage observations in February 2020. G. Weigelt, K.-H. Hofmann, D. Schertl, B. Lopez, R. G. Petrov, S. Lagarde, Ph. Berio, W. Jaffe, Th. Henning, F. Millour, A. Meilland, F. Allouche, S. Robbe-Dubois, A. Matter, P. Cruzalèbes, D. J. Hillier, C. M. P. Russell, T. Madura, T. R. Gull, M. F. Corcoran, A. Damineli, A. F. J. Moffat, P. W. Morris, N. D. Richardson, C. Paladini, M. Schöller, A. Mérand, A. Glindemann, U. Beckmann, M. Heininger, F. Bettonvil, G. Zins, J. Woillez, P. Bristow, J. Sanchez-Bermudez, K. Ohnaka, S. Kraus, A. Mehner, M. Wittkowski, C. A. Hummel, P. Stee, F. Vakili, H. Hartman, F. Navarete, K. Hamaguchi, D. A. Espinoza-Galeas, I. R. Stevens, R. van Boekel, S. Wolf, M. R. Hogerheijde, C. Dominik, J.-C. Augereau, E. Pantin, L. B. F. M. Waters, K. Meisenheimer, J. Varga, L. Klarmann, V. Gámez Rosas, L. Burtscher, J. Leftley, J. W. Isbell, V. Hocdé, G. Yoffe, E. Kokoulina, J. Hron, J. Groh, A. Kreplin, Th. Rivinius, W.-J. de Wit, W.-C. Danchi, A. Domiciano de Souza, J. Drevon, L. Labadie, C. Connot, E. Nußbaum, M. Lehmitz, P. Antonelli, U. Graser and C. Leinert. A&A, 652 (2021) A140; DOI: https://doi.org/10.1051/0004-6361/202141240 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||||||||||||||||||||||||||||||||||||||
| ID Code: | 111121 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Collection: | CaltechAUTHORS | ||||||||||||||||||||||||||||||||||||||||||||||||
| Deposited By: | Tony Diaz | ||||||||||||||||||||||||||||||||||||||||||||||||
| Deposited On: | 04 Oct 2021 20:23 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Last Modified: | 04 Oct 2021 20:23 |
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