@InProceedings{TeodoroDRMSRGMPWCPFGHHNAJCHGHG:2016:UnNaHe,
author = "Teodoro, Mairan and Damineli, Augusto and Richardson, Noel and
Moffat, Anthony F. J. and St-Jean, Lucas and Russel, Christopher
Michael Post and Gull, Theodore R. and Madura, Thomas and Pollard,
Karen and Walter, Frederick M. and Coimbra, Adriano and Prates,
Rodrigo and Fern{\'a}ndez-Laj{\'u}s, Eduardo and Gamen, Roberto
and Hickel, Gabriel and Henrique, William and Navarete, Felipe and
Andrade, Thiago and Jablonski, Francisco Jos{\'e} and Corcoran,
Michael F. and Hamaguchi, Kenji and Groh, Jose H. and Hillier,
Desmond John and Gerd, Weigelt",
affiliation = "USRA and {Universidade de S{\~a}o Paulo (USP)} and
{Universit{\'e} de Montr{\'e}al} and {Universit{\'e} de
Montr{\'e}al} and {Universit{\'e} de Montr{\'e}al} and
NASA/GSFC and NASA/GSFC and USRA and {University of Canterbury}
and {Stony Brook University} and LNA and LNA and {Universidad
Nacional de La Plata} and {Universidad Nacional de La Plata} and
{Universidade Federal de Itajub{\'a} (UNIFEI)} and {Universidade
Federal de Itajub{\'a} (UNIFEI)} and {Universidade de S{\~a}o
Paulo (USP)} and {Universidade de S{\~a}o Paulo (USP)} and
{Instituto Nacional de Pesquisas Espaciais (INPE)} and USRA and
CRESST and {Geneva Observatory} and {University of Pittsburgh} and
{Max-Planck-Institut f{\"u}r Radioastronomie}",
title = "Unveiling the nature of the He II \λ4686 periodic minima in
\η Carinae",
year = "2016",
organization = "American Astronautical Society, Meeting, 227.",
abstract = "\η Carinae is known to be a massive binary system, but some
of the orbital parameters remain uncertain. The nature of the
periodic minima seen in several spectral features are associated
with periastron passages near stellar conjunction, but its nature
has been interpreted either as a low excitation event or as an
eclipse of the hotter secondary star by the dense inner wind of
the primary. We conducted an intense spectroscopic monitoring of
the He II \λ4686 emission line across the 2014.6 event using
ground- and space-based telescopes. Comparison with results from
the past two events confirmed the stability of the equivalent
width and radial velocity of this line, as well as the strict
periodicity of its minima. In combination with different other
measurements, the orbital period is 2022.7 (±0.3) d. We adopted a
power law model in combination with the total opacity in the line
of sight to the apex of the wind-wind collision region obtained
from hydrodynamic simulations to reproduce the observed He II
\λ4686 equivalent width curve. We constrained the orbital
inclination to 135°153° and the longitude of periastron to
234°252°. Periastron passage occurred on T (2014.6)=2456874.4
(±1.3) d. With these orbital elements, we successfully reproduced
both the equivalent width curve observed from our direct view of
the central source and the polar view. This suggests that the He
II \λ4686 minimum is ultimately caused by an increase in the
opacity in the line of sight to the emitting region as the
secondary star moves behind the primary star and plunges into
denser regions of its wind.",
conference-location = "Kissimmee, FL",
conference-year = "4-8 Jan.",
targetfile = "Teodoro_unveiling.pdf",
urlaccessdate = "27 abr. 2024"
}