TY - GEN
T1 - Unveiling the nature of the He II λ4686 periodic minima in η Carinae
AU - Teodoro, Mairan
AU - Damineli, Augusto
AU - Richardson, Noel
AU - Moffat, Anthony F. J.
AU - St-Jean, Lucas
AU - Russell, Christopher Michael Post
AU - Gull, Theodore R.
AU - Madura, Thomas
AU - Pollard, Karen
AU - Walter, Frederick M.
AU - Coimbra, Adriano
AU - Prates, Rodrigo
AU - Fernández-Lajús, Eduardo
AU - gamen, roberto
AU - Hickel, Gabriel
AU - Henrique, William
AU - Navarete, Felipe
AU - Andrade, Thiago
AU - Jablonski, Francisco
AU - Corcoran, Michael F.
AU - Hamaguchi, Kenji
AU - Groh, Jose H.
AU - Hillier, Desmond John
AU - Gerd, Weigelt
AU - SASER Team Members, null
AU - Heathcote, Bernard
AU - Luckas, Paul
AU - Locke, Malcolm
AU - Powles, Jonathan
AU - Bohlsen, Terry
PY - 2016/1/1
Y1 - 2016/1/1
N2 - 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 T0(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.
AB - 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 T0(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.
M3 - Other contribution
T3 - American Astronomical Society Meeting
PB - American Astronomical Society
ER -