Dusty winds - II. Observational implications

Ivezić, Željko; Elitzur, Moshe

doi:10.1111/j.1365-2966.2010.16348.x

Cited by 26 publications

(28 citation statements)

References 41 publications

(58 reference statements)

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“…This is broadly consistent with the scaling relationṀ ∝ υ 3 ∞ , resulting from the SCRA scenario according to Elitzur and Ivezić (2001) and Ivezić and Elitzur (2010), who claim that this reflects the important role of drift between gas and dust in winds of AGB stars. As will be discussed in Sect.5.1, however, alternative interpretations are possible in the context of PEDDRO models.…”

Section: Mass-loss Ratessupporting

confidence: 90%

Mass loss of stars on the asymptotic giant branch

Höfner

Olofsson

2018

Astron Astrophys Rev

445

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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Section: Mass-loss Ratessupporting

confidence: 90%

Mass loss of stars on the asymptotic giant branch

Höfner

Olofsson

2018

Astron Astrophys Rev

445

376

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“…The measured angular growth rate of its rings, 0.07" in 6.5 yr, coupled with CO absorption observations (Bujarrabal et al 2001, Fong et al 2006 show that their outflow speed is 18 km s −1 . This result is in very close agreement with the predicted terminal velocity of radiation-drive dust winds in AGB stars by Ivezić & Elitzur (2010). Multi-epoch proper motion studies will prove to be a valuable new and new "movie camera" of proper motions in pPNe and PNe that extends our empirical understandings into the time domain.…”

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confidence: 84%

Planetary nebulae: 20 years of Hubble inquiry

Balick

2011

Proc. IAU

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Abstract. The Hubble Space Telescope has served the critical roles of microscope and movie camera in the past 20 years of research on planetary nebulae ("PNe"). We have glimpsed the details of the evolving structures of neutral and ionized post-AGB objects, built ingenious heuristic models that mimic these structures, and constrained most of the relevant physical processes with careful observations and interpretation. We have searched for close physical binary stars with spatial resolution ∼50 AU at 1 AU, located jets emerging from the nucleus at speeds up to 2000 km s −1 and matched newly discovered molecular and X-ray emission regions to physical substructures in order to better understand how stellar winds and ionizing radiation interact to form the lovely symmetries that are observed. Ultraviolet spectra of CNO in PNe help to uncover how stars process deep inside AGB stars with unstable nuclear burning zones. HST broadband imaging has been at the forefront of uncovering surprisingly complex wind morphologies produced at the tip of the AGB, and has led to an increasing realization of the potentially vital roles of close binary stars and emerging magnetic fields in shaping stellar winds.

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“…Given the bolometric luminosities (Table 1), we use the 1D radiative transfer code DUSTY (Ivezić et al 1999) to model the temperature profiles of our VeLLOs. We use the modeled cloud density distribution described in Section 4.3, which is scaled to the envelope masses of 0.5, 1.0, and 3.0M  within 10,000au.…”

Section: Models Of Temperature Profilesmentioning

confidence: 99%

Probing Episodic Accretion in Very Low Luminosity Objects

Hsieh

Murillo

Беллоче

et al. 2018

ApJ

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Episodic accretion has been proposed as a solution to the long-standing luminosity problem in star formation; however, the process remains poorly understood. We present observations of line emission from N 2 H + and CO isotopologues using the Atacama Large Millimeter/submillimeter Array (ALMA) in the envelopes of eight very low luminosity objects (VeLLOs). In five of the sources the spatial distribution of emission from N 2 H + and CO isotopologues shows a clear anticorrelation. It is proposed that this is tracing the CO snow line in the envelopes: N 2 H + emission is depleted toward the center of these sources, in contrast to the CO isotopologue emission, which exhibits a peak. The positions of the CO snow lines traced by the N 2 H + emission are located at much larger radii than those calculated using the current luminosities of the central sources. This implies that these five sources have experienced a recent accretion burst because the CO snow line would have been pushed outward during the burst because of the increased luminosity of the central star. The N 2 H + and CO isotopologue emission from DCE161, one of the other three sources, is most likely tracing a transition disk at a later evolutionary stage. Excluding DCE161, five out of seven sources (i.e., ∼70%) show signatures of a recent accretion burst. This fraction is larger than that of the Class 0/I sources studied by Jørgensen et al. and Frimann et al., suggesting that the interval between accretion episodes in VeLLOs is shorter than that in Class 0/I sources.

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Dusty winds - II. Observational implications

Cited by 26 publications

References 41 publications

Mass loss of stars on the asymptotic giant branch

Mass loss of stars on the asymptotic giant branch

Planetary nebulae: 20 years of Hubble inquiry

Probing Episodic Accretion in Very Low Luminosity Objects

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