Unveiling the nature of the He II λ4686 periodic minima in η Carinae

Mairan Teodoro, Augusto Damineli, Noel Richardson, Anthony F. J. Moffat, Lucas St-Jean, Christopher Michael Post Russell, Theodore R. Gull, Thomas Madura, Karen Pollard, Frederick M. Walter, Adriano Coimbra, Rodrigo Prates, Eduardo Fernández-Lajús, roberto gamen, Gabriel Hickel, William Henrique, Felipe Navarete, Thiago Andrade, Francisco Jablonski, Michael F. Corcoran & 10 others Kenji Hamaguchi, Jose H. Groh, Desmond John Hillier, Weigelt Gerd, SASER Team Members, Bernard Heathcote, Paul Luckas, Malcolm Locke, Jonathan Powles, Terry Bohlsen

Research output: Other contribution

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 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.
Original languageEnglish
PublisherAmerican Astronomical Society
Publication statusPublished - 1 Jan 2016

Publication series

NameAmerican Astronomical Society Meeting
PublisherAmerican Astronomical Society
Volume227

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stars
orbitals
conjunction
orbital elements
eclipses
curves
longitude
opacity
radial velocity
line of sight
inclination
periodic variations
apexes
telescopes
collisions
excitation
simulation

Cite this

Teodoro, M., Damineli, A., Richardson, N., Moffat, A. F. J., St-Jean, L., Russell, C. M. P., ... Bohlsen, T. (2016, Jan 1). Unveiling the nature of the He II λ4686 periodic minima in η Carinae. American Astronomical Society.
Teodoro, Mairan ; Damineli, Augusto ; Richardson, Noel ; Moffat, Anthony F. J. ; St-Jean, Lucas ; Russell, Christopher Michael Post ; Gull, Theodore R. ; Madura, Thomas ; Pollard, Karen ; Walter, Frederick M. ; Coimbra, Adriano ; Prates, Rodrigo ; Fernández-Lajús, Eduardo ; gamen, roberto ; Hickel, Gabriel ; Henrique, William ; Navarete, Felipe ; Andrade, Thiago ; Jablonski, Francisco ; Corcoran, Michael F. ; Hamaguchi, Kenji ; Groh, Jose H. ; Hillier, Desmond John ; Gerd, Weigelt ; SASER Team Members ; Heathcote, Bernard ; Luckas, Paul ; Locke, Malcolm ; Powles, Jonathan ; Bohlsen, Terry. / Unveiling the nature of the He II λ4686 periodic minima in η Carinae. 2016. American Astronomical Society. (American Astronomical Society Meeting).
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title = "Unveiling the nature of the He II λ4686 periodic minima in η Carinae",
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 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.",
author = "Mairan Teodoro and Augusto Damineli and Noel Richardson and Moffat, {Anthony F. J.} and Lucas St-Jean and Russell, {Christopher Michael Post} and Gull, {Theodore R.} and Thomas Madura and Karen Pollard and Walter, {Frederick M.} and Adriano Coimbra and Rodrigo Prates and Eduardo Fern{\'a}ndez-Laj{\'u}s and roberto gamen and Gabriel Hickel and William Henrique and Felipe Navarete and Thiago Andrade and Francisco Jablonski and Corcoran, {Michael F.} and Kenji Hamaguchi and Groh, {Jose H.} and Hillier, {Desmond John} and Weigelt Gerd and {SASER Team Members} and Bernard Heathcote and Paul Luckas and Malcolm Locke and Jonathan Powles and Terry Bohlsen",
year = "2016",
month = "1",
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language = "English",
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publisher = "American Astronomical Society",
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Teodoro, M, Damineli, A, Richardson, N, Moffat, AFJ, St-Jean, L, Russell, CMP, Gull, TR, Madura, T, Pollard, K, Walter, FM, Coimbra, A, Prates, R, Fernández-Lajús, E, gamen, R, Hickel, G, Henrique, W, Navarete, F, Andrade, T, Jablonski, F, Corcoran, MF, Hamaguchi, K, Groh, JH, Hillier, DJ, Gerd, W, SASER Team Members, Heathcote, B, Luckas, P, Locke, M, Powles, J & Bohlsen, T 2016, Unveiling the nature of the He II λ4686 periodic minima in η Carinae. American Astronomical Society.

Unveiling the nature of the He II λ4686 periodic minima in η Carinae. / Teodoro, Mairan; Damineli, Augusto; Richardson, Noel; Moffat, Anthony F. J.; St-Jean, Lucas; Russell, Christopher Michael Post; Gull, Theodore R.; Madura, Thomas; Pollard, Karen; Walter, Frederick M.; Coimbra, Adriano; Prates, Rodrigo; Fernández-Lajús, Eduardo; gamen, roberto; Hickel, Gabriel; Henrique, William; Navarete, Felipe; Andrade, Thiago; Jablonski, Francisco; Corcoran, Michael F.; Hamaguchi, Kenji; Groh, Jose H.; Hillier, Desmond John; Gerd, Weigelt; SASER Team Members; Heathcote, Bernard; Luckas, Paul; Locke, Malcolm; Powles, Jonathan; Bohlsen, Terry.

American Astronomical Society. 2016, . (American Astronomical Society Meeting; Vol. 227).

Research output: Other contribution

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 -

Teodoro M, Damineli A, Richardson N, Moffat AFJ, St-Jean L, Russell CMP et al. Unveiling the nature of the He II λ4686 periodic minima in η Carinae. 2016.