FOUR DECADES OF IRC +10216: EVOLUTION OF A CARBON-RICH DUST SHELL RESOLVED AT 10 μm WITH MMT ADAPTIVE OPTICS AND MIRAC4<sup>,</sup><sup>,</sup>

Males, Jared R.; Close, Laird M.; Skemer, Andrew J.; Hinz, Philip M.; Hoffmann, W. F.; Marengo, Massimo

doi:10.1088/0004-637x/744/2/133

Cited by 6 publications

(6 citation statements)

References 42 publications

(75 reference statements)

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“…If this is indeed the case, then we are fortunate to witness the onset of axisymmetric mass loss, starting as recently as 75 years ago, if we assume a typical outflow velocity for IRC+10216 of 10 km s −1 . Additional recent N-band (8-13 micron) observations show a change in the shape of the SiC spectral feature at 11 micron and a reduction in the continuum at 13 microns, which is interpreted as a change in the mass loss history over the last 20 years (Males et al 2012).…”

Section: "Torus" Modelmentioning

confidence: 83%

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Jeffers

Min

Waters

et al. 2014

A&A

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Aims. Understanding the formation of planetary nebulae remains elusive because in the preceding asymptotic giant branch (AGB) phase these stars are heavily enshrouded in an optically thick dusty envelope. Methods. To further understand the morphology of the circumstellar environments of AGB stars we observe the closest carbon-rich AGB star IRC+10216 in scattered light. Results. When imaged in scattered light at optical wavelengths, IRC+10216 surprisingly shows a narrow equatorial density enhancement, in contrast to the large-scale spherical rings that have been imaged much further out. We use radiative transfer models to interpret this structure in terms of two models: firstly, an equatorial density enhancement, commonly observed in the more evolved post-AGB stars, and secondly, in terms of a dust rings model, where a local enhancement of mass-loss creates a spiral ring as the star rotates. Conclusions. We conclude that both models can be used to reproduce the dark lane in the scattered light images, which is caused by an equatorially density enhancement formed by dense dust rather than a bipolar outflow as previously thought. We are unable to place constraints on the formation of the equatorial density enhancement by a binary system.

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Section: "Torus" Modelmentioning

confidence: 83%

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Jeffers

Min

Waters

et al. 2014

A&A

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“…There is ample evidence of departures from spherical symmetry in the inner regions of CSEs (Blasius et al 2012;Males et al 2012;Ohnaka et al 2016;Stewart et al 2016a). However, these results are not necessarily attributed to a non-spherical mass loss.…”

Section: Circumstellar Morphologymentioning

confidence: 99%

Mass loss of stars on the asymptotic giant branch

Höfner

Olofsson

2018

Astron Astrophys Rev

441

376

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As low-and intermediate-mass stars reach the asymptotic giant branch (AGB), they have developed into intriguing and complex objects that are major players in the cosmic gas/dust cycle. At this stage, their appearance and evolution are strongly affected by a range of dynamical processes. Large-scale convective flows bring newlyformed chemical elements to the stellar surface and, together with pulsations, they trigger shock waves in the extended stellar atmosphere. There, massive outflows of gas and dust have their origin, which enrich the interstellar medium and, eventually, lead to a transformation of the cool luminous giants into white dwarfs. Dust grains forming in the upper atmospheric layers play a critical role in the wind acceleration process, by scattering and absorbing stellar photons and transferring their outward-directed momentum to the surrounding gas through collisions. Recent progress in high-angularresolution instrumentation, from the visual to the radio regime, is leading to valuable new insights into the complex dynamical atmospheres of AGB stars and their windforming regions. Observations are revealing asymmetries and inhomogeneities in the photospheric and dust-forming layers which vary on time-scales of months, as well as more long-lived large-scale structures in the circumstellar envelopes. High-angularresolution observations indicate at what distances from the stars dust condensation occurs, and they give information on the chemical composition and sizes of dust grains in the close vicinity of cool giants. These are essential constraints for building B Susanne Höfner

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“…The Strehl ratio plots shown in Figs. 13,14,15,16, and 17 are horizontal lines for guide star magnitudes up to a guide star magnitude of K≈7. This high flux regime is dominated by the deformable mirror fitting error.…”

Section: Results Of the Selection Process Test Casesmentioning

confidence: 99%

Single conjugate adaptive optics for the ELT instrument METIS

et al. 2018

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The European Extremely Large Telescope (ELT) is a 39 m large, ground-based optical and near-to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around the middle of the next decade. All first light instruments will come with wavefront sensing devices that allow control of the ELT's intrinsic M4 and M5 wavefront correction units, thus building an adaptive optics (AO) system. To take advantage of the ELT's optical performance, full diffraction-limited operation is required and only a high performance AO system can deliver this. Further technically challenging requirements for the AO come from the exoplanet research field, where the task to resolve the very small angular separations between host star and planet, has also to take into account the high-contrast ratio between the two objects. We present in detail the results of our simulations and their impact on high-contrast imaging in order to find the optimal wavefront sensing device for the METIS instrument. METIS is the mid-infrared imager and spectrograph for the ELT with specialised high-contrast, coronagraphic imaging capabilities, whose performance strongly depends on the AO residual wavefront errors. We examined the sky and target sample coverage of a generic wavefront sensor in two spectral regimes, visible and near-infrared, to pre-select the spectral range for the more detailed wavefront sensor type analysis. We find that the near-infrared regime is the most suitable for METIS. We then analysed the performance of Shack-Hartmann and pyramid wavefront sensors under realistic conditions at the ELT, did a balancing with our scientific requirements, and concluded that a pyramid wavefront sensor is the best choice for METIS. For this choice we additionally examined the impact of noncommon path aberrations, of vibrations, and the long-term stability of the SCAO system including high-contrast imaging performance.Keywords Single conjugate adaptive optics · SCAO · ELT · Pyramid wavefront sensor · Shack-Hartmann wavefront sensor · Fragmented pupil · Low wind effect · Non-common path aberrations · High-contrast imaging

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FOUR DECADES OF IRC +10216: EVOLUTION OF A CARBON-RICH DUST SHELL RESOLVED AT 10 μm WITH MMT ADAPTIVE OPTICS AND MIRAC4^,^,

Cited by 6 publications

References 42 publications

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Mass loss of stars on the asymptotic giant branch

Single conjugate adaptive optics for the ELT instrument METIS

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FOUR DECADES OF IRC +10216: EVOLUTION OF A CARBON-RICH DUST SHELL RESOLVED AT 10 μm WITH MMT ADAPTIVE OPTICS AND MIRAC4,,

Cited by 6 publications

References 42 publications

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Surprising detection of an equatorial dust lane on the AGB star IRC+10216

Mass loss of stars on the asymptotic giant branch

Single conjugate adaptive optics for the ELT instrument METIS

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FOUR DECADES OF IRC +10216: EVOLUTION OF A CARBON-RICH DUST SHELL RESOLVED AT 10 μm WITH MMT ADAPTIVE OPTICS AND MIRAC4^,^,