He II λ4686 IN η CARINAE: COLLAPSE OF THE WIND-WIND COLLISION REGION DURING PERIASTRON PASSAGE

Teodoro, Mairan; Damineli, A.; Arias, J. I.; Araújo, F. X. de; Barbá, R. H.; Corcoran, M. F.; Fernandes, M. Borges; Fernández-Lajús, E.; Fraga, L.; Gamen, R.; González, J. F.; Groh, J. H.; Marshall, J. L.; McGregor, Peter; Morrell, N.; Nicholls, David C.; Parkin, E. R.; Pereira, C. B.; Phillips, M. M.; Solivella, G. R.; Steiner, J. E.; Stritzinger, M. D.; Thompson, I. B.; Torres, C. A. O.; Torres, M. A. P.; Herencia, Maria Isela Zevallos

doi:10.1088/0004-637x/746/1/73

Cited by 42 publications

(77 citation statements)

References 76 publications

(120 reference statements)

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“…First, we note that, based on previous works, the mass-loss rate of η A is very likely not as low as the value assumed in the Case C situation (see arguments in e.g. Hillier et al 2006;Parkin et al 2009;Teodoro et al 2012Teodoro et al , 2013Russell 2013;M12;M13), and so we will not be using the SimpleX results obtained here for Case C to model the observed broad, high-ionization forbidden line emission. Rather, in addition to investigating how a reducedṀ η A affects the ionization structure on the apastron side of the system, we use Case C as an illustrative example to determine whether η B 's ionizing radiation can penetrate the dense WWIRs and further affect the ionization state of η A 's wind.…”

Section: Influence Of the Primary Star η Amentioning

confidence: 80%

“…The only caveat is that we do not account for any possible ionization of η A 's pre-shock wind to He iii by soft Xrays produced in the 420 km s −1 η A shock. However, any such He iii region near the WWIR zone at times around apastron is very likely to be negligible in extent, if it exists at all, as evidenced by the absence of any significant detectable He ii λ4686 emission in η Car during its spectroscopic high state (Mehner et al 2011;Teodoro et al 2012).…”

Section: Influence Of the Primary Star η Amentioning

confidence: 99%

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3D radiative transfer in η Carinae: application of the SIMPLEX algorithm to 3D SPH simulations of binary colliding winds

Clementel

Madura

Kruip

et al. 2014

Monthly Notices of the Royal Astronomical Society

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Eta Carinae is an ideal astrophysical laboratory for studying massive binary interactions and evolution, and stellar wind-wind collisions. Recent three-dimensional (3D) simulations set the stage for understanding the highly complex 3D flows in η Car. Observations of different broad high-and low-ionization forbidden emission lines provide an excellent tool to constrain the orientation of the system, the primary's mass-loss rate, and the ionizing flux of the hot secondary. In this work we present the first steps towards generating synthetic observations to compare with available and future HST/STIS data. We present initial results from full 3D radiative transfer simulations of the interacting winds in η Car. We use the SimpleX algorithm to post-process the output from 3D SPH simulations and obtain the ionization fractions of hydrogen and helium assuming three different mass-loss rates for the primary star. The resultant ionization maps of both species constrain the regions where the observed forbidden emission lines can form. Including collisional ionization is necessary to achieve a better description of the ionization states, especially in the areas shielded from the secondary's radiation. We find that reducing the primary's mass-loss rate increases the volume of ionized gas, creating larger areas where the forbidden emission lines can form. We conclude that post processing 3D SPH data with SimpleX is a viable tool to create ionization maps for η Car.

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Section: Influence Of the Primary Star η Amentioning

confidence: 80%

Section: Influence Of the Primary Star η Amentioning

confidence: 99%

3D radiative transfer in η Carinae: application of the SIMPLEX algorithm to 3D SPH simulations of binary colliding winds

Clementel

Madura

Kruip

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…During the spectroscopic event many emission and absorption lines and bands show considerable changes for a few weeks (Damineli et al 2008 and references therein), e.g., a deep minimum in the X-ray emission. The X-ray emission, for example, comes from the colliding stellar winds, (Corcoran 2005;Corcoran et al 2010;Parkin et al 2011;Akashi et al 2006Akashi et al , 2011Moffat & Corcoran 2009;Henley et al 2008;Okazaki et al 2008;Pittard & Corcoran 2002Behar et al 2007;Teodoro et al 2012), while its minimum is attributed to the suppression of the secondary wind near periastron passages. This suppression occurs when the colliding-wind region comes very close to the secondary star as the two stars approach each other, and the secondary gravity acts on the dense postshock primary wind (Kashi & Soker 2009b).…”

Section: Introductionmentioning

confidence: 99%

The interaction of the eta carinae primary wind with a century old slow equatorial ejecta

Soker¹,

Kashi²

2012

New Astronomy

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We argue that the asymmetric morphology of the blue and red shifted components of the outflow at hundreds of AU from the massive binary system η Carinae can be understood from the collision of the primary stellar wind with the slowly expanding dense equatorial gas. Recent high spatial observations of some forbidden lines, e.g. [Fe III] λ4659, reveal the outflowing gas within about one arcsecond (2300 AU) from η Car. The distribution of the blue and red shifted components are not symmetric about the center, and they are quite different from each other. The morphologies of the blue and red shifted components correlate with the location of dense slowly moving equatorial gas (termed the Weigelt blob environment; WBE), that is thought to have been ejected during the 1887 -1895 Lesser Eruption (LE). In our model the division to the blue and red shifted components is caused by the postshock flow of the primary wind on the two sides of the equatorial plane after it collides with the WBE. The fast wind from the secondary star plays no role in our model for these components, and it is the freely expanding primary wind that collides with the WBE. Because the line of sight is inclined to the binary axis, the two components are not symmetric. We show that the postshock gas can also account for the observed intensity in the [Fe III] λ4659 line.

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“…Just before periastron, the He ii λ4686 line intensity increases suddenly and then drops sharply to zero, after which it recovers to a second peak before declining back to zero (Steiner & Damineli 2004;Martin et al 2006;Mehner et al 2011;Teodoro et al 2012). Based on the density and energy required for the formation of this line, the most plausible region in which it can form during periastron passage is close to the WWIR apex (Martin et al 2006;Teodoro et al 2012).…”

Section: Discussionmentioning

confidence: 99%

“…As summarized in C14b, helium spectral features provide important information on both the geometry and physical properties of the η Car binary and the individual stars. While various helium features are present throughout the entire orbit, they show their most interesting behavior during periastron passage (Nielsen et al 2007;Damineli et al 2008a;Teodoro et al 2012).…”

Section: Introductionmentioning

confidence: 99%

3D radiative transfer simulations of Eta Carinae's inner colliding winds – II. Ionization structure of helium at periastron

Clementel

Madura

Kruip

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Spectral observations of the massive colliding wind binary Eta Carinae show phasedependent variations, in intensity and velocity, of numerous helium emission and absorption lines throughout the entire 5.54-year orbit. Approaching periastron, the 3D structure of the wind-wind interaction region (WWIR) gets highly distorted due to the eccentric (e ∼ 0.9) binary orbit. The secondary star (η B ) at these phases is located deep within the primary's dense wind photosphere. The combination of these effects is thought to be the cause of the particularly interesting features observed in the helium lines at periastron. We perform 3D radiative transfer simulations of η Car's interacting winds at periastron. Using the simplex radiative transfer algorithm, we post-process output from 3D smoothed particle hydrodynamic simulations of the inner 150 au of the η Car system for two different primary star mass-loss rates (Ṁ η A ). Using previous results from simulations at apastron as a guide for the initial conditions, we compute 3D helium ionization maps. We find that, for higherṀ η A , η B He 0+ -ionizing photons are not able to penetrate into the pre-shock primary wind. He + due to η B is only present in a thin layer along the leading arm of the WWIR and in a small region close to the stars. LoweringṀ η A allows η B 's ionizing photons to reach the expanding unshocked secondary wind on the apastron side of the system, and create a low fraction of He + in the pre-shock primary wind. With apastron on our side of the system, our results are qualitatively consistent with the observed variations in strength and radial velocity of η Car's helium emission and absorption lines, which helps better constrain the regions where these lines arise.

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He II λ4686 IN η CARINAE: COLLAPSE OF THE WIND-WIND COLLISION REGION DURING PERIASTRON PASSAGE

Cited by 42 publications

References 76 publications

3D radiative transfer in η Carinae: application of the SIMPLEX algorithm to 3D SPH simulations of binary colliding winds

3D radiative transfer in η Carinae: application of the SIMPLEX algorithm to 3D SPH simulations of binary colliding winds

The interaction of the eta carinae primary wind with a century old slow equatorial ejecta

3D radiative transfer simulations of Eta Carinae's inner colliding winds – II. Ionization structure of helium at periastron

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