Formation of Transition Alumina Dust around Asymptotic Giant Branch Stars: Condensation Experiments using Induction Thermal Plasma Systems

Takigawa, Aki; Kim, Tae-Hee; Igami, Yohei; Umemoto, Tatsuki; Tsuchiyama, A.; Koike, C.; Matsuno, Junya; Watanabe, Takayuki

doi:10.3847/2041-8213/ab1f80

Cited by 18 publications

(15 citation statements)

References 33 publications

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“…The infrared (IR) transmission spectra of the pellets in the wavelength range from 400-7500 cm −1 (1.3-25.0 µm) were measured with a JASCO MFT-680 at Kyoto University. For comparison, we also obtained IR spectra of quartz, amorphous silica (Takigawa et al 2019), amorphous enstatite, and amorphous forsterite (Imai 2012). FE-SEM analysis was performed on a JEOL JSM-7001F equipped with an Oxford Int.…”

Section: Sample Analysismentioning

confidence: 99%

“…Synthetic experiments based on the condensation model are generally performed using an induction thermal plasma (ITP) furnace to form GEMS analog particles in order to investigate the formation process and possible origins of GEMS (Tanaka et al 2014;Matsuno et al 2021;Kim et al 2021). The ITP system generates a rapid cooling of gas from high temperatures which simulates the environment in which condensation of cosmic dust occurs (Takigawa et al 2019;Matsuno et al 2021;Kim et al 2021). Matsuno et al (2021) first successfully synthesized textures similar to GEMS, where multiple Fe-metal grains are included in Mg-rich amorphous silicate by using S-free CI and GEMS-mean compositions while systematically changing the redox conditions.…”

Section: Introductionmentioning

confidence: 99%

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Condensation of cometary silicate dust using an induction thermal plasma system

Enju

Kawano

Tsuchiyama

et al. 2022

A&A

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Glass with embedded metal and sulfides (GEMS), the major components of chondritic-porous interplanetary dust particles (CP-IDPs), is one of the most primitive materials in the Solar System and may be analogous to the amorphous silicate dust observed in various astronomical environments. Mineralogical characteristics of GEMS should reflect their formation process and condition. In this study, synthetic experiments in the sulfur-bearing system of Fe-Mg-Si-O-S were performed with a systematic change in redox conditions using thermal plasma systems to reproduce the mineralogy and textures of GEMS. The resulting condensates were composed of amorphous silicates with Fe-bearing nano-inclusions. The Fe content and texture in the amorphous silicates as well as the mineral phases of the nanoparticles correlate with redox conditions. Fe dissolved in the amorphous silicate as FeO in oxidizing conditions formed Fe-metal nanoparticles in intermediate redox conditions, and gupeiite (Fe 3 Si) nanoparticles in reducing conditions. In intermediate to reducing redox conditions, Fe-poor amorphous silicate formed a biphasic texture with Mg-and Si-rich regions, indicating liquid immiscibility during the melt phase. Most Fe-metal particles were surrounded by FeS and formed on the surface of amorphous silicate grains. Condensates produced in intermediate to slightly reducing redox conditions resemble GEMS in that they have similar mineral assemblages and chemical compositions to amorphous silicate, except that the Fe-metal grains are absent from the interior of the amorphous silicate grains. This textural difference can be explained by the sulfidation at high temperatures in this study, in contrast to sulfidation occurring at low temperatures in the presence of H 2 in natural GEMS formation. Based on the twoliquid structures observed in the experimental products and in GEMS, also recognized in infrared (IR) spectra, we propose that GEMS condensed as silicate melt under limited redox conditions followed by incorporation of multiple metal grains into the silicate melt or by aggregation of core-shell structured grains before sulfidation of the metallic iron. Condensates produced in oxidizing conditions are similar to GEMS-like material in the matrices of primitive carbonaceous chondrite meteorites, indicating the possibility that they form by direct condensation from nebula gas in relatively oxidizing conditions compared to GEMS.

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Section: Sample Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Condensation of cometary silicate dust using an induction thermal plasma system

Enju

Kawano

Tsuchiyama

et al. 2022

A&A

View full text Add to dashboard Cite

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“…In the present study, we perform condensation experiments using a simple system of MgO-SiO 2 and a sulfur-free CI chondritic composition to reproduce GEMS-like grains from a gas. The condensates synthesized in the ITP systems can be compared with the circumstellar dust formation conditions by scaling the experimental conditions in the ITP systems (Matsuno et al 2021;Takigawa et al 2019). The condensation conditions of GEMS compared with those of the present experiments are discussed based on nucleation and growth theory from vapor (Yamamoto & Hasegawa 1977;Kozasa & Hasegawa 1987).…”

Section: Introductionmentioning

confidence: 96%

Condensation of cometary silicate dust using an induction thermal plasma system I. Enstatite and CI chondritic composition

Kim,

Takigawa,

Tsuchiyama

et al. 2021

Preprint

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Glass with embedded metal and sulfides (GEMS) is a major component of chondritic porous interplanetary dust particles. Although GEMS is one of the most primitive components in the Solar System, its formation process and conditions have not been constrained. We performed condensation experiments of gases in the system of Mg-Si-O (MgSiO 3 composition) and of the S-free CI chondritic composition (Si-Mg-Fe-Na-Al-Ca-Ni-O system) in induction thermal plasma equipment. Amorphous Mg-silicate particles condensed in the experiments of the Mg-Si-O system, and their grain size distribution depended on the experimental conditions (mainly partial pressure of SiO). In the CI chondritic composition experiments, irregularly shaped amorphous silicate particles of less than a few hundred nanometers embedded with multiple Fe-Ni nanoparticles of ≤20 nm were successfully synthesized. These characteristics are very similar to those of GEMS, except for the presence of FeSi instead of sulfide grains. We propose that the condensation of amorphous silicate grains smaller than a few tens of nanometers and with metallic cores, followed by coagulation, could be the precursor material that forms GEMS prior to sulfidation.

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“…Mid-infrared observations show the presence of alumina dust (amorphous Al 2 O 3 ) in the extended envelopes of O-rich AGB stars. Although only recent condensation experiments confirmed that amorphous alumina can condense in circumstellar conditions [5], intermediate mass (IM) AGB stars have been considered to be the main source of alumina dust in the galaxy for many years, starting from the first work by Onaka et al [6], to the most recent ones Dell'Agli et al [7], Ventura et al [8] (and the references therein).…”

Section: Introductionmentioning

confidence: 99%

Group II Oxide Grains: How Massive Are Their AGB Star Progenitors?

et al. 2021

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Presolar grains and their isotopic compositions provide valuable constraints to AGB star nucleosynthesis. However, there is a sample of O- and Al-rich dust, known as group 2 oxide grains, whose origin is difficult to address. On the one hand, the 17O/16O isotopic ratios shown by those grains are similar to the ones observed in low-mass red giant stars. On the other hand, their large 18O depletion and 26Al enrichment are challenging to account for. Two different classes of AGB stars have been proposed as progenitors of this kind of stellar dust: intermediate mass AGBs with hot bottom burning, or low mass AGBs where deep mixing is at play. Our models of low-mass AGB stars with a bottom-up deep mixing are shown to be likely progenitors of group 2 grains, reproducing together the 17O/16O, 18O/16O and 26Al/27Al values found in those grains and being less sensitive to nuclear physics inputs than our intermediate-mass models with hot bottom burning.

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Formation of Transition Alumina Dust around Asymptotic Giant Branch Stars: Condensation Experiments using Induction Thermal Plasma Systems

Cited by 18 publications

References 33 publications

Condensation of cometary silicate dust using an induction thermal plasma system

Condensation of cometary silicate dust using an induction thermal plasma system

Condensation of cometary silicate dust using an induction thermal plasma system I. Enstatite and CI chondritic composition

Group II Oxide Grains: How Massive Are Their AGB Star Progenitors?

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