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He II lambda 4686 EMISSION FROM THE MASSIVE BINARY SYSTEM IN eta CAR: CONSTRAINTS TO THE ORBITAL ELEMENTS AND THE NATURE OF THE PERIODIC MINIMA

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Autor(es):
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Teodoro, M. [1, 2] ; Damineli, A. [3] ; Heathcote, B. [4] ; Richardson, N. D. [5, 6] ; Moffat, A. F. J. [6] ; St-Jean, L. [6] ; Russell, C. [7, 1] ; Gull, T. R. [1] ; Madura, T. I. [1, 8] ; Pollard, K. [9] ; Walter, F. [10] ; Coimbra, A. [11] ; Prates, R. [11] ; Fernandez-Lajus, E. [12, 13] ; Gamen, R. C. [12, 13] ; Hickel, G. [14] ; Henrique, W. [14] ; Navarete, F. [3] ; Andrade, T. [3] ; Jablonski, F. [15] ; Luckas, P. [4, 16] ; Locke, M. [4, 17] ; Powles, J. [4] ; Bohlseni, T. [4] ; Chinii, R. [18, 19] ; Corcoran, M. F. [20] ; Hamaguchi, K. [7, 20, 21] ; Groh, J. H. [22] ; Hillier, D. J. [23, 24] ; Weigelt, G. [25]
Número total de Autores: 30
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[1] NASA, Goddard Space Flight Ctr, Astrophys Sci Div, Code 667, Greenbelt, MD 20771 - USA
[2] Western Michigan Univ, Kalamazoo, MI 49008 - USA
[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, R Matao 1226, Cidade Univ, BR-05508900 Sao Paulo - Brazil
[4] SASER Team, 269 Domain Rd, South Yarra, Vic 3141 - Australia
[5] Univ Toledo, Dept Phys & Astron, Ritter Observ, Toledo, OH 43606 - USA
[6] Univ Montreal, Dept Phys, CP 6128, Succursale Ctr Ville, Montreal, PQ H3C 3J7 - Canada
[7] NASA, Goddard Space Flight Ctr, Xray Astrophys Lab, Greenbelt, MD 20771 - USA
[8] Univ Space Res Assoc, 7178 Columbia Gateway Dr, Columbia, MD 20146 - USA
[9] Univ Canterbury, Dept Phys & Astron, Christchurch 1 - New Zealand
[10] SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 - USA
[11] Lab Nacl Astrof, R Estados Unidos 154, BR-37504364 Bairro Das Nacoes, Itajuba - Brazil
[12] Univ Nacl La Plata, Fac Ciencias Astron & Geofis, Paseo Bosque S-N, B1900FWA, RA-1900 La Plata, Buenos Aires - Argentina
[13] Consejo Nacl Invest Cient & Tecn, Inst Astrofis La Plata, Paseo Bosque S-N, B1900FWA, La Plata, Buenos Aires - Argentina
[14] Univ Fed Itajuba, Inst Fis & Quim, Ave BPS 1303, BR-37500062 Pinheirinho, Itajuba - Brazil
[15] Inst Nacl Pesquisas Espaciais, Div Astrofis, Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos - Brazil
[16] Univ Western Australia, 35 Stirling Highway, Perth, WA 6009 - USA
[17] Canterbury Astron Soc, Canterbury, Kent - England
[18] Ruhr Univ Bochum, Astron Inst, Univ Str 150, D-44780 Bochum - Germany
[19] Univ Catolica Norte, Inst Astron, Ave Angamos 0610, Casilla 1280, Antofagasta - Chile
[20] NASA, Goddard Space Flight Ctr, CRESST, Greenbelt, MD 20771 - USA
[21] Univ Maryland Baltimore Cty, 1000 Hilltop Circle, Baltimore, MD 21250 - USA
[22] Observ Geneva, Chemin Maillettes 51, CH-1290 Versoix - Switzerland
[23] Univ Pittsburgh, Dept Phys & Astron, 3941 OHara St, Pittsburgh, PA 15260 - USA
[24] Univ Pittsburgh, Pittsburgh Particle Phys Astrophys & Cosmol Ctr, 3941 OHara St, Pittsburgh, PA 15260 - USA
[25] Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn - Germany
Número total de Afiliações: 25
Tipo de documento: Artigo Científico
Fonte: ASTROPHYSICAL JOURNAL; v. 819, n. 2 MAR 10 2016.
Citações Web of Science: 17
Resumo

Eta Carinae (eta Car) is an extremely massive binary system in which rapid spectrum variations occur near periastron. Most notably, near periastron the He II lambda 4686 line increases rapidly in strength, drops to a minimum value, then increases briefly before fading away. To understand this behavior, we conducted an intense spectroscopic monitoring of the He II lambda 4686 emission line across the 2014.6 periastron passage using ground-and space-based telescopes. Comparison with previous data confirmed the overall repeatability of the line equivalent width (EW), radial velocities, and the timing of the minimum, though the strongest peak was systematically larger in 2014 than in 2009 by 26%. The EW variations, combined with other measurements, yield an orbital period of 2022.7 +/- 0.3 days. The observed variability of the EW was reproduced by a model in which the line flux primarily arises at the apex of the wind-wind collision and scales inversely with the square of the stellar separation, if we account for the excess emission as the companion star plunges into the hot inner layers of the primary's atmosphere, and including absorption from the disturbed primary wind between the source and the observer. This model constrains the orbital inclination to 135 degrees-153 degrees, and the longitude of periastron to 234 degrees-252 degrees. It also suggests that periastron passage occurred on T-0 = 2456874.4 (+/- 1.3 days). Our model also reproduced EW variations from a polar view of the primary star as determined from the observed He II lambda 4686 emission scattered off the Homunculus nebula. (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