η Carinae across the 2003.5 Minimum: Spectroscopic Evidence for Massive Binary Interactions

Nielsen, K. E.; Corcoran, M. F.; Gull, Theodore R.; Hillier, D. J.; Hamaguchi, Kenji; Ivarsson, Stefan; Lindler, Don J.

doi:10.1086/513006

Cited by 91 publications

(179 citation statements)

References 45 publications

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“…Studies of the binary or binary wind-wind collision zone were reported by many authors (e.g., Damineli 1996;Damineli et al 1997Damineli et al , 1998Damineli et al , 2000Damineli et al , 2008bDavidson 1997;Davidson et al 2005Davidson et al , 2015Smith & Gehrz 2000;Smith et al 2004;Smith 2010;Pittard & Corcoran 2002;Corcoran et al 1997Corcoran et al , 2001Corcoran 2005;Ishibashi et al 1999;Soker 2003Soker , 2007Weis et al 2005;Gull et al 2006Gull et al , 2009Gull et al , 2011Gull et al , 2016Nielsen et al 2007;Weigelt et al 2007; Kashi & Soker 2007, 2009aParkin et al 2009;Groh et al 2010Groh et al , 2012bMadura & Owocki 2010;Madura et al 2012Madura et al , 2013Mehner et al 2010aMehner et al , 2011Mehner et al , 2012Mehner et al , 2015Richardson et al 2010;Teodoro et al 2013Teodoro et al , 2016Clementel et al 2015a,b;Hamaguchi et al 2016). The X-ray...…”

Section: Introductionmentioning

confidence: 99%

VLTI-AMBER velocity-resolved aperture-synthesis imaging ofηCarinae with a spectral resolution of 12 000

Weigelt

Hofmann

Schertl

et al. 2016

A&A

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Context. The mass loss from massive stars is not understood well. η Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Aims. We want to investigate the structure and kinematics of η Car's primary star wind and wind-wind collision zone with a high spatial resolution of ∼6 mas (∼14 au) and high spectral resolution of R = 12 000. Methods. Observations of η Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision.Results. We present velocity-resolved aperture-synthesis images reconstructed in more than 100 different spectral channels distributed across the Brγ 2.166 µm emission line. The intensity distribution of the images strongly depends on wavelength. At wavelengths corresponding to radial velocities of approximately −140 to −376 km s −1 measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of −277 km s −1 , the position angle of the symmetry axis of the fan is ∼126 • . The fan-shaped structure extends approximately 8.0 mas (∼18.8 au) to the southeast and 5.8 mas (∼13.6 au) to the northwest, measured along the symmetry axis at the 16% intensity contour. The shape of the intensity distributions suggests that the obtained images are the first direct images of the innermost wind-wind collision zone. Therefore, the observations provide velocity-dependent image structures that can be used to test three-dimensional hydrodynamical, radiative transfer models of the massive interacting winds of η Car.

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Section: Introductionmentioning

confidence: 99%

VLTI-AMBER velocity-resolved aperture-synthesis imaging ofηCarinae with a spectral resolution of 12 000

Weigelt

Hofmann

Schertl

et al. 2016

A&A

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“…The second component is probably a late-type nitrogen-rich O or Wolf-Rayet (WR) star (Iping et al 2005;Verner et al 2005). The semi-major axis of the orbit is 16.64 AU (Hillier et al 2001) and the eccentricity is very high (e ∼ 0.9, Nielsen et al 2007). Thus, the periastron distance r periastron is around 1.66 AU, while the primary star's radius R ,1 , although poorly constrained, is estimated to be in the range 0.7-1 AU (respectively, Corcoran & Hamaguchi 2007;Damineli 1996).…”

Section: Introductionmentioning

confidence: 99%

ηCarinae: a very large hadron collider

Farnier

Walter

Leyder

2010

A&A

109

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Context. η Carinae is the colliding wind binary with the highest mass-loss rate in our Galaxy and the only one in which hard X-ray emission has been detected. Aims. η Carinae is therefore a primary candidate to search for particle acceleration by probing its gamma-ray emission. Methods. We used the first 21 months of Fermi/LAT data to extract gamma-ray (0.2-100 GeV) images, spectra, and light-curves, then combined them with multi-wavelength observations to model the non-thermal spectral energy distribution. Results. A bright gamma-ray source is detected at the position of η Carinae. Its flux at a few 100 MeV can be modelled by an extrapolation of the hard X-ray spectrum towards higher energies. The spectral energy distribution features two distinct components. The first one extends from the keV to GeV energy range, and features an exponential cutoff at ∼1 GeV. It can be understood as inverse Compton scattering of ultraviolet photons by electrons accelerated up to γ ∼ 10 4 in the colliding wind region. The expected synchrotron emission is compatible with the existing upper limit to the non-thermal radio emission. The second component is a hard gamma-ray tail detected above 20 GeV. It could be explained by π 0 -decay of accelerated hadrons interacting with the dense stellar wind. The ratio of the fluxes of the π 0 to inverse Compton components is roughly as predicted by simulations of colliding wind binaries. This hard gamma-ray tail can only be understood if emitted close to the wind collision region. The energy transferred to the accelerated particles (∼5% of the collision mechanical energy) is comparable to that of the thermal X-ray emission. Conclusions. The electron spectrum responsible for the keV to GeV emission was modelled and the observed emission above 20 GeV strongly suggests hadronic acceleration in η Carinae. These observations are thus in good agreement with the colliding wind scenario proposed for η Carinae.

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“…• (e.g., Moffat & Corcoran 2009;Okazaki et al 2008;Henley et al 2008;Hamaguchi et al 2007;Nielsen et al 2007;Gull et al 2011;Madura 2010;Madura et al 2011Madura & Groh 2012;Parkin et al 2009). Some other papers claim an opposite view, namely ω ≃ 90…”

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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η Carinae across the 2003.5 Minimum: Spectroscopic Evidence for Massive Binary Interactions

Cited by 91 publications

References 45 publications

VLTI-AMBER velocity-resolved aperture-synthesis imaging ofηCarinae with a spectral resolution of 12 000

VLTI-AMBER velocity-resolved aperture-synthesis imaging ofηCarinae with a spectral resolution of 12 000

ηCarinae: a very large hadron collider

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

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