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To v(infinity) and beyond! The He I absorption variability across the 2014.6 periastron passage of eta Carinae

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Richardson, Noel D. ; Madura, Thomas I. ; St-Jean, Lucas ; Moffat, Anthony F. J. ; Gull, Theodore R. ; Russell, Christopher M. P. ; Damineli, Augusto ; Teodoro, Mairan ; Corcoran, Michael F. ; Walter, Frederick M. ; Clementel, Nicola ; Groh, Jose H. ; Hamaguchi, Kenji ; Hillier, D. John
Número total de Autores: 14
Tipo de documento: Artigo Científico
Fonte: Monthly Notices of the Royal Astronomical Society; v. 461, n. 3, p. 2540-2558, SEP 21 2016.
Citações Web of Science: 11
Resumo

We have monitored the massive binary star. Carinae with the CTIO/Small and Moderate Aperture Research Telescope System 1.5 m telescope and CHIRON spectrograph from the previous apastron passage of the system through the recent 2014.6 periastron passage. Our monitoring has resulted in a large, homogeneous data set with an unprecedented time-sampling, spectral resolving power, and signal to noise. This allowed us to investigate temporal variability previously unexplored in the system and discover a kinematic structure in the P Cygni absorption troughs of neutral helium wind lines. The features observed occurred prior to the periastron passage and are seen as we look through the trailing arm of the wind-wind collision shock cone. We show that the bulk of the variability is repeatable across the last five periastron passages, and that the absorption occurs in the inner 230 au of the system. In addition, we found an additional, high-velocity absorption component superimposed on the P Cygni absorption troughs that has been previously unobserved in these lines, but which bears resemblance to the observations of the He I lambda 10830 angstrom feature across previous cycles. Through a comparison of the current smoothed particle hydrodynamical simulations, we show that the observed variations are likely caused by instabilities in the wind-wind collision region in our line of sight, coupled with stochastic variability related to clumping in the winds. (AU)

Processo FAPESP: 11/51680-6 - Explorando o universo: da formação de galáxias aos planetas tipo-terra, com o Telescópio Gigante Magellan
Beneficiário:João Evangelista Steiner
Linha de fomento: Auxílio à Pesquisa - Projetos Especiais