A New Method of Determining the Characteristics of Evolved Binary Systems Revealed in the Observed Circumstellar Patterns: Application to Afgl 3068

Kim, Hyosun; Taam, Ronald E.

doi:10.1088/2041-8205/759/1/l22

Cited by 34 publications

(59 citation statements)

References 27 publications

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“…The green zone represents the instrumental calibration errors. The blue vertical line respresents the Σ value found in the hydrodynamical simulations of Kim & Taam (2012). This translates, in the optically thin regime, into an uncertainty on the mass loss which is approximately a factor 1.3 greater than the uncertainty on the line flux (a flux uncertainty of a factor ten transflates into an uncertainty in deduced mass loss of a factor thirteen). For optically thick spectral lines, the uncertainty on the mass-loss is approximately a factor of 2.5 smaller than the uncertainty on the line flux (a flux uncertainty of a factor ten transflates to an uncertainty in deduced mass loss of a factor four).…”

Section: Impact Of the Spiral Structure On The Total Line Strengthsmentioning

confidence: 70%

“…The blue line in Fig. 16 represents the mass ratio Σ that was derived for the wind structure of the binary AGB system AFGL 3068 by Kim & Taam (2012). It shows that for this particular system one would not derive a significantly different total mass-loss rate if one would have applied a spherical outflow model.…”

Section: Impact Of the Spiral Structure On The Total Line Strengthsmentioning

confidence: 88%

“…T * and R * are the stellar effective temperature and stellar radius respectively. The temperature of the spiral, is superposed onto this background, with a chosen distribution maximum of T 0 (r, θ, φ) = T 0 = 60 K, corresponding to a value of the same order of magnitude as established from hydrodynamical calculations (Kim & Taam 2012). The resulting overall temperature profile of the spiral wind is T wind (r, θ, φ) = T HO (r) + T spiral (r, θ, φ).…”

Section: Model Assumptionsmentioning

confidence: 99%

“…This distance can, if caused by binary interactions, directly be related to local physics according to Kim & Taam (2012) via the relation…”

Section: Constraining the Geometrymentioning

confidence: 99%

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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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Section: Impact Of the Spiral Structure On The Total Line Strengthsmentioning

confidence: 70%

Section: Impact Of the Spiral Structure On The Total Line Strengthsmentioning

confidence: 88%

Section: Model Assumptionsmentioning

confidence: 99%

“…This distance can, if caused by binary interactions, directly be related to local physics according to Kim & Taam (2012) via the relation…”

Section: Constraining the Geometrymentioning

confidence: 99%

See 2 more Smart Citations

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

Homan

Decin

Koter

et al. 2015

A&A

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show abstract

“…Such systems can in principle be progenitors of type Ia supernovae and their circumstellar environment could cause observed absorption line variability first observed in supernova type Ia 2006X (Patat et al, 2007). The same code was used to simulate spiral shocks imprinted by a wide binary companion in a long orbit with an AGB star, as seen by ALMA in Section 4.1, see also Figure 3 (for a similar approach, see also the work of Kim & Taam (2012)). …”

Section: Hydrodynamic Models Of Binary Interactions Do Exist But 12mentioning

confidence: 99%

Dawes Review 6: The Impact of Companions on Stellar Evolution

Marco

Izzard

2017

Publ. Astron. Soc. Aust.

188

136

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Astrophysicists are increasingly taking into account the effects of orbiting companions on stellar evolution. New discoveries have underlined the role of binary star interactions in a range of astrophysical events, including some that were previously interpreted as being due uniquely to single stellar evolution. We review classical binary phenomena, such as type Ia supernovae, and discuss new phenomena, such as intermediate luminosity transients, gravitational wave-producing double black holes, and the interaction between stars and their planets. Finally, we reassess well-known phenomena, such as luminous blue variables, in light of interpretations that include both single and binary stars. At the same time we contextualise the new discoveries within the framework of binary stellar evolution. The last decade has seen a revival in stellar astrophysics as the complexity of stellar observations is increasingly interpreted with an interplay of single and binary scenarios. The next decade, with the advent of massive projects such as the Square Kilometre Array, the James Webb Space Telescope, and increasingly sophisticated computational methods, will see the birth of an expanded framework of stellar evolution that will have repercussions in many other areas of astrophysics such as galactic evolution and nucleosynthesis.

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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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A New Method of Determining the Characteristics of Evolved Binary Systems Revealed in the Observed Circumstellar Patterns: Application to Afgl 3068

Cited by 34 publications

References 27 publications

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

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

Dawes Review 6: The Impact of Companions on Stellar Evolution

Mass loss of stars on the asymptotic giant branch

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