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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

He II lambda 4686 IN eta CARINAE: COLLAPSE OF THE WIND-WIND COLLISION REGION DURING PERIASTRON PASSAGE

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Author(s):
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Teodoro, M. [1] ; Damineli, A. [1] ; Arias, J. I. [2] ; de Araujo, F. X. [3] ; Barba, R. H. [4] ; Corcoran, M. F. [5, 6] ; Borges Fernandes, M. [3] ; Fernandez-Lajus, E. [7] ; Fraga, L. [8] ; Gamen, R. C. [7] ; Gonzalez, J. F. [4] ; Groh, J. H. [9] ; Marshall, J. L. [10] ; McGregor, P. J. [11] ; Morrell, N. [12] ; Nicholls, D. C. [11] ; Parkin, E. R. [11] ; Pereira, C. B. [3] ; Phillips, M. M. [12] ; Solivella, G. R. [7] ; Steiner, J. E. [1] ; Stritzinger, M. [13] ; Thompson, I. [14] ; Torres, C. A. O. [15] ; Torres, M. A. P. [16] ; Zevallos Herencia, M. I. [3]
Total Authors: 26
Affiliation:
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[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil
[2] Univ La Serena, Dept Fis, La Serena - Chile
[3] Observ Nacl, BR-20921400 Rio De Janeiro - Brazil
[4] Consejo Nacl Invest Cient & Tecn, ICATE, San Juan - Argentina
[5] CRESST, Greenbelt, MD 20771 - USA
[6] NASA, Goddard Space Flight Ctr, Xray Astrophys Lab, Greenbelt, MD 20771 - USA
[7] Univ Nacl La Plata, Fac Ciencias Astron & Geofis, La Plata, BA - Argentina
[8] So Observ Astrophys Res, La Serena - Chile
[9] Max Planck Inst Radioastron, D-53121 Bonn - Germany
[10] Texas A&M Univ, Dept Phys & Astron, College Stn, TX 77843 - USA
[11] RSAA, Mt Stromlo Observ, Weston, ACT 2611 - Australia
[12] Observ Carnegie Inst Washington, Las Campanas Observ, La Serena - Chile
[13] Stockholm Univ, Dept Astron, Oskar Klein Ctr, S-10691 Stockholm - Sweden
[14] Observ Carnegie Inst, Pasadena, CA 91101 - USA
[15] Lab Nacl Astrofis, BR-37504364 Bairro Das Nacoes, Itajuba - Brazil
[16] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 - USA
Total Affiliations: 16
Document type: Journal article
Source: ASTROPHYSICAL JOURNAL; v. 746, n. 1 FEB 10 2012.
Web of Science Citations: 24
Abstract

The periodic spectroscopic events in eta Carinae are now well established and occur near the periastron passage of two massive stars in a very eccentric orbit. Several mechanisms have been proposed to explain the variations of different spectral features, such as an eclipse by the wind-wind collision (WWC) boundary, a shell ejection from the primary star or accretion of its wind onto the secondary. All of them have problems explaining all the observed phenomena. To better understand the nature of the cyclic events, we performed a dense monitoring of eta Carinae with five Southern telescopes during the 2009 low-excitation event, resulting in a set of data of unprecedented quality and sampling. The intrinsic luminosity of the He II lambda 4686 emission line (L similar to 310 L-circle dot) just before periastron reveals the presence of a very luminous transient source of extreme UV radiation emitted in the WWC region. Clumps in the primary's wind probably explain the flare-like behavior of both the X-ray and He II lambda 4686 light curves. After a short-lived minimum, He II lambda 4686 emission rises again to a new maximum, when X-rays are still absent or very weak. We interpret this as a collapse of the WWC onto the ``surface{''} of the secondary star, switching off the hard X-ray source and diminishing the WWC shock cone. The recovery from this state is controlled by the momentum balance between the secondary's wind and the clumps in the primary's wind. (AU)

FAPESP's process: 09/08013-9 - Analysis of the long-term variations in the spectrum of Eta Carinae and a data-reduction pipeline for STELES spectrograph
Grantee:Mairan Macedo Teodoro
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 05/00190-8 - Spectral analysis of long-term variations of η Carinae brightness
Grantee:Mairan Macedo Teodoro
Support type: Scholarships in Brazil - Doctorate