Why is the Red Rectangle Unique?

Winckel, H. Van

doi:10.1017/s1743921313015822

Cited by 3 publications

(3 citation statements)

References 23 publications

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“…Also, the stellar temperature increases for PPNe, generating significant UV radiation which may also thermally process the grains. Toward PPNe, the v = 1–0 vibrationally excited lines of H 2 near 2 μm were observed, which are clear shock indicators . These lines are not observed in AGB stars but become visible in the PPNe phase.…”

Section: Discussionsupporting

confidence: 79%

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Destructive Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes

2022

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The detection of the fullerenes C60 and C70 in the interstellar medium (ISM) has transformed our understanding of chemical complexity in space. These discoveries also raise the possibility for the presence of even larger molecules in astrophysical environments. Here we report in situ heating of analog silicon carbide (SiC) presolar grains using transmission electron microscopy (TEM). These heating experiments are designed to simulate the temperature conditions occurring in post-AGB stellar envelopes. Our experimental findings reveal that heating the analog SiC grains to the point of decomposition initially yields hemispherical C60-sized nanostructures, with five- and six-membered rings, which transform into multiwalled carbon nanotubes (MWCNTs) if held isothermally >2 min. These MWCNTs are certainly larger than any of the currently observed interstellar fullerene species, both in overall size and number of C atoms. These experimental simulations suggest that such MWCNTs are likely to form in post-AGB circumstellar material, where the structures, along with the smaller fullerenes, are subsequently injected into the ISM.

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Section: Discussionsupporting

confidence: 79%

“…Toward PPNe, the v = 1−0 vibrationally excited lines of H 2 near 2 μm were observed, which are clear shock indicators. 40 The largest currently known interstellar molecules are the fullerenes C 60 and C 70 . While C 60 is comprised of 60 carbon atoms, its diameter is 0.7 nm.…”

Section: ■ Discussionmentioning

confidence: 99%

Destructive Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes

2022

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“…Based on our results, we predict that post-AGB intermediate binaries (post-AGBIB) that launch narrow jets will produce bipolar nebulae. A known example for such a system is the red rectangle, HD 44179 [36].…”

Section: The Onset Of the Geementioning

confidence: 99%

The Morphology of the Outflow in the Grazing Envelope Evolution

Shiber

2018

Galaxies

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We study the grazing envelope evolution (GEE), where a secondary star, which orbits the surface of a giant star, accretes mass from the giant envelope and launches jets. We conduct simulations of the GEE with different half-opening angles and velocities, and simulate the onset phase and the spiralling-in phase. We discuss the resulting envelope structure and the outflow geometry. We find in the simulations of the onset phase with narrow jets that a large fraction of the ejected mass outflows along the polar directions. The mass ejected at these directions has the fastest velocity and the highest angular momentum magnitude. In the simulations of the spiralling-in phase, a large fraction of the ejected mass concentrates around the orbital plane. According to our findings, the outflow with the highest velocity is closer to the poles as we launch narrower jets. The outflow has a toroidal shape accompanied by two faster rings, one ring at each side of the equatorial plane. The interaction of the jets with the giant envelope causes these outflow structures, as we do not include in our simulations the secondary star gravity and the envelope self-gravity.

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Further ALMA observations and detailed modeling of the Red Rectangle

Bujarrabal

Castro-Carrizo

Santander-García

et al. 2016

A&A

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We confirm the presence of a rotating equatorial disk and an outflow, which is mainly formed of gas leaving the disk. The mass of the disk is ~ 0.01 , and that of the CO-rich outflow is around ten times smaller. High temperatures of ≳ 100 K are derived for most components. From comparison of the mass values, we roughly estimate the lifetime of the rotating disk, which is found to be of about 10000 yr. Taking data of a few other post-AGB composite nebulae into account, we find that the lifetimes of disks around post-AGB stars typically range between 5000 and more than 20000 yr. The angular momentum of the disk is found to be high, ~ 9 AU km s, which is comparable to that of the stellar system at present. Our observations of HCN show a particularly wide velocity dispersion and indicate that this molecule is only abundant in the inner Keplerian disk, at ≲ 60 AU from the stellar system. We suggest that HCN is formed in a dense photodissociation region (PDR) due to the UV excess known to be produced by the stellar system, following chemical mechanisms that are well established for interstellar medium PDRs and disks orbiting young stars. We further suggest that this UV excess could lead to an efficient formation and excitation of PAHs and other C-bearing macromolecules, whose emission is very intense in the optical counterpart.

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Why is the Red Rectangle Unique?

Cited by 3 publications

References 23 publications

Destructive Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes

Destructive Processing of Silicon Carbide Grains: Experimental Insights into the Formation of Interstellar Fullerenes and Carbon Nanotubes

The Morphology of the Outflow in the Grazing Envelope Evolution

Further ALMA observations and detailed modeling of the Red Rectangle

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