The fossil wind structures of Eta Carinae: changes across one 5.54-yr cycle

Gull, Theodore R.; Madura, Thomas; Teodoro, Mairan; Clementel, Nicola; Corcoran, M. F.; Damineli, A.; Groh, J. H.; Hamaguchi, Kenji; Hillier, D. J.; Moffat, A. F. J.; Richardson, Noel D.; Weigelt, G.; Lindler, Don J.; Feggans, K.

doi:10.1093/mnras/stw1829

Cited by 34 publications

(69 citation statements)

References 60 publications

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“…4 to 6 and B.1 is mainly visible at velocities between approximately −426 and −339 km s −1 . Its PA of ∼225 • approximately agrees with the PA of the fossil wind structure reported by Gull et al (2011Gull et al ( , 2016 and the polarisation bar (Falcke et al 1996). The images of the fossil wind structure (at ∼0.1-0.5 ) in Gull et al (2011) were made by integrating the HST/STIS observations over the velocity range of −400 to −200 km s −1 (see also the wind studies in Gull et al 2009;Madura & Owocki 2010;Teodoro et al 2013).…”

Section: Fossil Windsupporting

confidence: 84%

“…2b in the polarimetry paper) shows a bar with a length of ∼0.4 along a PA of ∼45 and 225 • , which was interpreted as an obscuring equatorial disk. Interestingly, this polarized 45 • bar has approximately the same length and PA as the fossil wind bar discovered by Gull et al (2011Gull et al ( , 2016.…”

Section: Introductionsupporting

confidence: 52%

“…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%

“…Detailed HST/STIS imaging of η Car with a resolution of about 0.1 allowed Gull et al (2009), Mehner et al (2010a, Teodoro et al (2013), and Gull et al (2016) to image the circumstellar environment of η Car across emission lines and at several orbital phases. The discovered structures are the result of the wind-wind collision over the past ∼20 yr.…”

Section: Introductionmentioning

confidence: 99%

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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: Fossil Windsupporting

confidence: 84%

Section: Introductionsupporting

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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show abstract

“…It traces a complex of dust knots that marks the peak brightness in mid-IR images of the Homunculus, because there is a complex of dusty knots close to the star where the dust is heated to high temperatures, and where the inside edges of these dust clumps are ionized by UV radiation. Some of the brightest of these ionized knots are known as the "Weigelt knots" (Weigelt & Ebersberger 1986;Weigelt et al 1995), which have received much observational attention, although images show several other knots in the vicinity (Smith et al 2004a;Chesneau et al 2005;Gull et al 2016). This dust feature is found in what is otherwise a gap in the CO and cool dust torus -yet this clump appears to have remained.…”

Section: The Co and Ir Torusmentioning

confidence: 99%

A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA

Smith

Ginsburg

Bally

2017

Monthly Notices of the Royal Astronomical Society

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We present Atacama Large Millimeter Array (ALMA) observations of 12 CO 2−1 emission from circumstellar material around the massive star η Carinae. These observations reveal new structural details about the cool equatorial torus located ∼4000 au from the star. The CO torus is not a complete azimuthal loop, but rather, is missing its near side, which appears to have been cleared away. The missing material matches the direction of apastron in the eccentric binary system, making it likely that η Car's companion played an important role in disrupting portions of the torus soon after ejection. Molecular gas seen in ALMA data aligns well with the cool dust around η Car previously observed in mid-infrared (IR) maps, whereas hot dust resides at the inner surface of the molecular torus. The CO also coincides with the spatial and velocity structure of near-IR H 2 emission. Together, these suggest that the CO torus seen by ALMA is actually the pinched waist of the Homunculus polar lobes, which glows brightly because it is close to the star and warmer than the poles. The near side of the torus appears to be a blowout, associated with fragmented equatorial ejecta. We discuss implications for the origin of various features northwest of the star. CO emission from the main torus implies a total gas mass in the range of 0.2 -1 M ⊙ (possibly up to 5 M ⊙ or more, although with questionable assumptions). Deeper observations are needed to constrain CO emission from the cool polar lobes.

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4-D Imaging and Modeling of Eta Carinae’s Inner Fossil Wind Structures

Madura¹,

Gull²,

Teodoro³

et al. 2016

Proc. IAU

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Eta Carinae is the most massive active binary within 10,000 light-years and is famous for the largest non-terminal stellar explosion ever recorded. Observations reveal that the supermassive (~120 M⊙) binary, consisting of an LBV and either a WR or extreme O star, undergoes dramatic changes every 5.54 years due to the stars’ very eccentric orbits (e ≈ 0.9). Many of these changes are caused by a dynamic wind-wind collision region (WWCR) between the stars, plus expanding fossil WWCRs formed one, two, and three 5.54-year cycles ago. The fossil WWCRs can be spatially and spectrally resolved by the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). Starting in June 2009, we used the HST/STIS to spatially map Eta Carinae’s fossil WWCRs across one full orbit, following temporal changes in several forbidden emission lines (e.g. [Feiii] 4659 Å, [Feii] 4815 Å), creating detailed data cubes at multiple epochs. Multiple wind structures were imaged, revealing details about the binary’s orbital motion, photoionization properties, and recent (~5 − 15 year) mass-loss history. These observations allow us to test 3-D hydrodynamical and radiative-transfer models of the interacting winds. Our observations and models strongly suggest that the wind and photoionization properties of Eta Carinae’s binary have not changed substantially over the past several orbital cycles. They also provide a baseline for following future changes in Eta Carinae, essential for understanding the late-stage evolution of this nearby supernova progenitor. For more details, see Gull et al. (2016) and references therein.

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The fossil wind structures of Eta Carinae: changes across one 5.54-yr cycle

Cited by 34 publications

References 60 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

A disrupted molecular torus around Eta Carinae as seen in 12CO with ALMA

4-D Imaging and Modeling of Eta Carinae’s Inner Fossil Wind Structures

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