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Distinguishing circumstellar from stellar photometric variability in Eta Carinae

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Autor(es):
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Damineli, A. [1] ; Fernandez-Lajus, E. [2, 3] ; Almeida, L. A. [1, 4] ; Corcoran, M. F. [5, 6, 7] ; Damineli, D. S. C. [8] ; Gull, T. R. [9] ; Hamaguchi, K. [10, 5, 6] ; Hillier, D. J. [11, 12] ; Jablonski, F. J. [13] ; Madura, T. I. [14] ; Moffat, A. F. J. [15, 16] ; Navarete, F. [1] ; Richardson, N. D. [17] ; Ruiz, G. F. [1] ; Salerno, N. E. [2] ; Scalia, M. C. [2, 3] ; Weigelt, G. [18]
Número total de Autores: 17
Afiliação do(s) autor(es):
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[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, Cidade Univ, BR-05508090 Sao Paulo, SP - Brazil
[2] Univ Nacl La Plata, Fac Ciencias Astron & Geofis, Paseo Bosque S-N, B1900FWA, La Plata, Buenos Aires - Argentina
[3] UNLP, CONICET, CCT La Plata, Inst Astrofis La Plata, B1900FWA, La Plata, Buenos Aires - Argentina
[4] Univ Fed Rio Grande do Norte, Dept Fis, UFRN, CP 1641, BR-59072970 Natal, RN - Brazil
[5] NASA, CRESST 2, Goddard Space Plight Ctr, Code 662, Greenbelt, MD 20771 - USA
[6] NASA, Xray Astrophys Lab, Goddard Space Plight Ctr, Code 662, Greenbelt, MD 20771 - USA
[7] Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 - USA
[8] Univ Maryland, Dept Mol Genet & Cell Biol, College Pk, MD 20742 - USA
[9] NASA, Lab Extraterr Planets & Stellar Astrophys, Goddard Space Flight Ctr, Code 667, Greenbelt, MD 20771 - USA
[10] Univ Maryland Baltimore Cty, Dept Phys, 1000 Hilltop Circle, Baltimore, MD 21250 - USA
[11] Univ Pittsburgh, Dept Phys & Astron, 3941 OHara St, Pittsburgh, PA 15260 - USA
[12] Univ Pittsburgh, Pittsburgh Particle Phys Astrophys & Cosmol Ctr P, 3941 OHara St, Pittsburgh, PA 15260 - USA
[13] Inst Nacl Pesquisas Espaciais, MCTIC Ave Astronautas 1758, BR-12227010 Sao Jose Dos Campos, SP - Brazil
[14] San Jose State Univ, Dept Phys & Astron, One Washington Sq, San Jose, CA 95192 - USA
[15] Univ Montreal, Dept Phys, CP 6128, Succ Ctr Ville, Montreal, PQ H3C 3J7 - Canada
[16] Univ Montreal, CRAQ, CP 6128, Succ Ctr Ville, Montreal, PQ H3C 3J7 - Canada
[17] Univ Toledo, Dept Phys & Astron, Ritter Observ, Toledo, OH 43606 - USA
[18] Max Planck Inst Radio Astron, Hugel 69, D-53121 Bonn - Germany
Número total de Afiliações: 18
Tipo de documento: Artigo Científico
Fonte: Monthly Notices of the Royal Astronomical Society; v. 484, n. 1, p. 1325-1346, MAR 2019.
Citações Web of Science: 2
Resumo

The interacting binary Eta Carinae remains one of the most enigmatic massive stars in our Galaxy despite over four centuries of observations. In this work, its light curve from the ultraviolet to the near-infrared is analysed using spatially resolved HST observations and intense monitoring at the La Plata Observatory, combined with previously published photometry. We have developed a method to separate the central stellar object in the ground-based images using HST photometry and applying it to the more numerous ground-based data, which supports the hypothesis that the central source is brightening faster than the almost-constant Homunculus. After detrending from long-term brightening, the light curve shows periodic orbital modulation (Delta V similar to 0.6 mag) attributed to the wind-wind collision cavity as it sweeps around the primary star and it shows variable projected area to our line-of-sight. Two quasi-periodic components with time-scales of 2-3 and 8-10 yr and low amplitude, Delta V < 0.2 mag, are superimposed on the brightening light curve, being the only stellar component of variability found, which indicates minimal stellar instability. Moreover, the light-curve analysis shows no evidence of `shell ejections' at periastron. We propose that the long-term brightening of the stellar core is due to the dissipation of a dusty clump in front of the central star, which works like a natural coronagraph. Thus, the central stars appear to be more stable than previously thought since the dominant variability originates from a changing circumstellar medium. We predict that the brightening phase, due mainly to dust dissipation, will be completed around 2032 +/- 4 yr, when the star will be brighter than in the 1600s by up to Delta V similar to 1 mag. (AU)

Processo FAPESP: 17/18191-8 - Formação de estrelas de alta massa: a massa do objeto central e a física da acreção
Beneficiário:Felipe Donizeti Teston Navarete
Linha de fomento: Bolsas no Brasil - Pós-Doutorado
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
Processo FAPESP: 12/09716-6 - Distâncias precisas de aglomerados jovens através de binárias eclipsantes massivas
Beneficiário:Leonardo Andrade de Almeida
Linha de fomento: Bolsas no Brasil - Pós-Doutorado
Processo FAPESP: 13/18245-0 - Soluções orbitais espectroscópicas completas para mais de 100 binárias massivas na região do "starburst" 30 Dourados
Beneficiário:Leonardo Andrade de Almeida
Linha de fomento: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado