Evidence of a Binary-Induced Spiral From an Incomplete Ring Pattern of Cit 6

Kim, Hyosun; Hsieh, I-Ta; Liu, Sheng-Yuan; Taam, Ronald E.

doi:10.1088/0004-637x/776/2/86

Cited by 42 publications

(69 citation statements)

References 48 publications

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“…High-resolution imaging of a few dusty AGB stars reveals bipolar or more complex, clumpy structures (e.g., Weigelt et al 1998;Monnier et al 2000;Hofmann et al 2001). Some AGB stars show spiral structures, which strongly suggests the influence of a companion (e.g., Mauron & Huggins 2006;Maercker et al 2012;Kim et al 2013;Ramstedt et al 2014;Mayer et al 2014;Decin et al 2015). These observations suggest that the seed of the morphological change already exists in the AGB phase.…”

Section: Introductionmentioning

confidence: 92%

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

Ohnaka

Schertl

Hofmann

et al. 2015

A&A

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Aims. The red giant L 2 Pup started a dimming event in 1994, which is considered to be caused by the ejection of dust clouds. We present near-IR aperture-synthesis imaging of L 2 Pup achieved by combining data from VLT/NACO and the AMBER instrument of the Very Large Telescope Interferometer (VLTI). Our aim is to spatially resolve the innermost region of the circumstellar environment. Methods. We carried out speckle interferometric observations at 2.27 µm with VLT/NACO and long-baseline interferometric observations with VLTI/AMBER at 2.2-2.35 µm with baselines of 15-81 m. We also extracted an 8.7 µm image from the mid-IR VLTI instrument MIDI.Results. The diffraction-limited image obtained by bispectrum speckle interferometry with NACO with a spatial resolution of 57 mas shows an elongated component. The aperture-synthesis imaging combining the NACO speckle data and AMBER data with a spatial resolution of 5.6 × 7.3 mas further resolves not only this elongated component, but also the central star. The reconstructed image reveals that the elongated component is a nearly edge-on disk with a size of ∼180 × 50 mas lying in the E-W direction, and furthermore, that the southern hemisphere of the central star is severely obscured by the equatorial dust lane of the disk. The angular size of the disk is consistent with the distance that the dust clouds that were ejected at the onset of the dimming event should have traveled by the time of our observations, if we assume that the dust clouds moved radially. This implies that the formation of the disk may be responsible for the dimming event. The 8.7 µm image with a spatial resolution of 220 mas extracted from the MIDI data taken in 2004 (seven years before the AMBER and NACO observations) shows an approximately spherical envelope without a signature of the disk. This suggests that the mass loss before the dimming event may have been spherical.

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Section: Introductionmentioning

confidence: 92%

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

Ohnaka

Schertl

Hofmann

et al. 2015

A&A

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“…As a consequence, spirals can often be seen instead as concentric arcs. Ways to derive properties of the binary system based on the CSE morphology are discussed in Huggins et al (2009), Kim and Taam (2012c), and Kim et al (2013), and interpretations of observed morphologies through hydrodynamical simulations can be found in, e.g., Maercker et al (2012) and Kim et al (2017), Fig. 21, right panel.…”

Section: Impacts Of Companions On Cse Morphologymentioning

confidence: 99%

Mass loss of stars on the asymptotic giant branch

Höfner

Olofsson

2018

Astron Astrophys Rev

442

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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“…Bowers & Johnston 1990), spirals (e.g. Mauron & Huggins 2006;Mayer et al 2011;Maercker et al 2012;Kim et al 2013), tori (e.g. Skinner et al 1998), and bubbles .…”

Section: Introductionmentioning

confidence: 99%

Simplified models of stellar wind anatomy for interpreting high-resolution data

Homan

Decin

Koter

et al. 2015

A&A

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Context. Recent high-resolution observations have shown that stellar winds harbour complexities that strongly deviate from spherical symmetry, which generally is assumed as standard wind model. One such morphology is the Archimedean spiral, which is generally believed to be formed by binary interactions, as has been directly observed in multiple sources. Aims. We seek to investigate the manifestation in the observables of spiral structures embedded in the spherical outflows of cool stars. We aim to provide an intuitive bedrock with which upcoming ALMA data can be compared and interpreted. Methods. By means of an extended parameter study, we modelled rotational CO emission from the stellar outflow of asymptotic giant branch stars. To this end, we developed a simplified analytical parametrised description of a 3D spiral structure. This model is embedded into a spherical wind and fed into the 3D radiative transfer code LIME, which produces 3D intensity maps throughout velocity space. Subsequently, we investigated the spectral signature of rotational transitions of CO in the models, as well as the spatial aspect of this emission by means of wide-slit position-velocity (PV) diagrams. Additionally, we quantified the potential for misinterpreting the 3D data in a 1D context. Finally, we simulated ALMA observations to explore the effect of interferometric noise and artefacts on the emission signatures. Results. The spectral signatures of the CO rotational transition v = 0 J = 3−2 are very efficient at concealing the dual nature of the outflow. Only a select few parameter combinations allow for the spectral lines to disclose the presence of the spiral structure. If the spiral cannot be distinguished from the spherical signal, this might result in an incorrect interpretation in a 1D context. Consequently, erroneous mass-loss rates would be calculated. The magnitude of these errors is mainly confined to a factor of a few, but in extreme cases can exceed an order of magnitude. CO transitions of different rotationally excited levels show a characteristical evolution in their line shape that can be brought about by an embedded spiral structure. However, if spatial information on the source is also available, the use of wide-slit PV diagrams systematically expose the embedded spiral. The PV diagrams also readily provide most of the geometrical and physical properties of the spiral-harbouring wind. Simulations of ALMA observations prove that the choice of antenna configuration is strongly dependent on the geometrical properties of the spiral. We conclude that exploratory endeavours should observe the object of interest with a range of different maximum-baseline configurations.

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Evidence of a Binary-Induced Spiral From an Incomplete Ring Pattern of Cit 6

Cited by 42 publications

References 48 publications

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

Mass loss of stars on the asymptotic giant branch

Simplified models of stellar wind anatomy for interpreting high-resolution data

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Evidence of a Binary-Induced Spiral From an Incomplete Ring Pattern of Cit 6

Cited by 42 publications

References 48 publications

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L2Puppis

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L2Puppis

Mass loss of stars on the asymptotic giant branch

Simplified models of stellar wind anatomy for interpreting high-resolution data

Contact Info

Product

Resources

About

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis