VLTI-MATISSE chromatic aperture-synthesis imaging of η Carinae's stellar wind across the Brα line: Periastron passage observations in February 2020
| Autor: | Th. Rivinius, C. M. P. Russell, A. Domiciano de Souza, Uwe Beckmann, Lucas Labadie, F. Allouche, P. Cruzalèbes, Sylvie Robbe-Dubois, Antoine Mérand, William C. Danchi, A. F. J. Moffat, Kenji Hamaguchi, Michael F. Corcoran, József Varga, Alexis Matter, Thomas I. Madura, Stephane Lagarde, Sebastian Wolf, Anthony Meilland, Walter Jaffe, Paul Bristow, T. R. Gull, Felix Bettonvil, D. A. Espinoza-Galeas, Jose H. Groh, J. C. Augereau, Carsten Dominik, W. J. de Wit, Markus Schöller, J. Leftley, V. Hocdé, Uwe Graser, R. van Boekel, F. Navarete, L. Klarmann, K. Ohnaka, Leonard Burtscher, Th. Henning, Karl-Heinz Hofmann, Augusto Damineli, Ian R. Stevens, C. Connot, Klaus Meisenheimer, Stefan Kraus, Patrick W. Morris, G. Yoffe, Michiel R. Hogerheijde, Romain Petrov, Ph. Berio, M. Heininger, Henrik Hartman, J. W. Isbell, Markus Wittkowski, Eric Pantin, E. Kokoulina, J. Drevon, Julien Woillez, L. B. F. M. Waters, E. Nußbaum, Dieter Schertl, Bruno Lopez, Alexander Kreplin, Gerd Weigelt, Florentin Millour, D. J. Hillier, J. Hron, M. Lehmitz, V. Gámez Rosas, J. Sanchez-Bermudez, Noel D. Richardson, C. A. Hummel, Claudia Paladini, Andrea Mehner, Farrokh Vakili, Andreas Glindemann, P. Antonelli, C. Leinert, Gérard Zins, Philippe Stee |
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| Přispěvatelé: | Low Energy Astrophysics (API, FNWI) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Interferometric
Astronomy Astrophysics::High Energy Astrophysical Phenomena Continuum (design consultancy) individual: eta Carinae [stars] Context (language use) Outflows Individual Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Winds 01 natural sciences Spectral line outflows Mass-Loss general [binaries] massive [stars] Astronomi astrofysik och kosmologi 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astronomy Astrophysics and Cosmology winds [stars] General 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Line (formation) O-type star Physics 010308 nuclear & particles physics Binaries Astronomy and Astrophysics mass-loss [stars] Radius Stars Techniques interferometric [techniques] Luminous blue variable 13. Climate action Space and Planetary Science Massive Astrophysics::Earth and Planetary Astrophysics η Carinae |
| Zdroj: | Astronomy & Astrophysics, 652:A140. EDP Sciences Astronomy & Astrophysics, 652 Astronomy & Astrophysics, 652, 1-22 Astronomy & Astrophysics, 652, pp. 1-22 |
| ISSN: | 0004-6361 1432-0746 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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