The Interplay Between Chemistry and Nucleation in the Formation of Carbonaceous Dust in Supernova Ejecta

We model dust formation in the core collapse supernova explosion SN 1987A by treating the gas-phase formation of dust grain nuclei as a chemical process. To compute the synthesis of fourteen species of grains we integrate a non-equilibrium network of nucleating and related chemical reactions and follow the growth of the nuclei into grains via accretion and coagulation. The effects of the radioactive 56 Co, 57 Co, 44 Ti, and 22 Na on the thermodynamics and chemistry of the ejecta are taken into account. The grain temperature, which we allow to differ from the gas temperature, affects the surface-tension-corrected evaporation rate. We also account for He + , Ne + , Ar + , and O weathering. We combine our dust synthesis model with a crude prescription for anisotropic 56 Ni dredge-up into the core ejecta, the so-called "nickel bubbles", to compute the total dust mass and molecular-species-specific grain size distribution. The total mass varies between 0.41 M and 0.73 M , depending on the bubble shell density contrast. In the decreasing order of abundance, the grain species produced are: magnesia, silicon, forsterite, iron sulfide, carbon, silicon dioxide, alumina, and iron. The combined grain size distribution is a power law dN/da ∝ a −4.39 . Early ejecta compaction by expanding radioactive 56 Ni bubbles strongly enhances dust synthesis. This underscores the need for improved understanding of hydrodynamic transport and mixing over the entire pre-homologous expansion.

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“…We take the rate per unit volume of this reaction to be k He c He + c n , where the coefficient is (Lazzati & Heger 2016):…”

Section: Weatheringmentioning

confidence: 99%

Molecular nucleation theory of dust formation in core-collapse supernovae applied to SN 1987A

Sluder

Milosavljević

Montgomery

2018

Monthly Notices of the Royal Astronomical Society

101

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“…These clumps cool down faster than the surroundings and are likely sites of dust condensation. Models of CO formation predict that the CO abundance should decrease from ∼ 600 days to ∼ 1000 days (Cherchneff & Lilly 2008;Lazzati & Heger 2016) for fully mixed case, and that as CO mass decreases, carbon dust forms.…”

Section: Co and Dust Formation In Supernovaementioning

confidence: 99%

Early formation of carbon monoxide in the Centaurus A supernova SN 2016adj

Banerjee

Joshi

Evans

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present near-infrared spectroscopy of the NGC 5128 supernova SN 2016adj in the first 2 months following discovery. We report the detection of first overtone carbon monoxide emission at ∼ 58.2 d after discovery, one of the earliest detections of CO in an erupting supernova. We model the CO emission to derive the CO mass, temperature and velocity, assuming both pure 12 CO and a composition that includes 13 CO; the case for the latter is the isotopic analyses of meteoritic grains, which suggest that core collapse supernovae can synthesise significant amounts of 13 C. Our models show that, while the CO data are adequately explained by pure 12 CO, they do not preclude the presence of 13 CO, to a limit of 12 C/ 13 C> 3, the first constraint on the 12 C/ 13 C ratio determined from near-infrared observations. We estimate the reddening to the object, and the effective temperature from the energy distribution at outburst. We discuss whether the ejecta of SN 2016adj may be carbon-rich, what the infrared data tell us about the classification of this supernova, and what implications the early formation of CO in supernovae may have for CO formation in supernovae in general.

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“…If the rate of CO formation exceeds the rate of carbonaceous dust condensation, then recently freed carbon will immediately capture onto nearby oxygen before sinking to the midplane. However, the rate of thermal CO formation decreases exponentially with the declining disk temperature (Lazzati & Heger 2016), such that as the disk continues to cool solid formation may eventually come to eclipse CO formation. This could occur even in regions of the disk which remain shielded by X-rays and hence are conducive to the required gas phase chemistry.…”

Section: Planet Formation Scenariomentioning

confidence: 99%

Merger of a white dwarf–neutron star binary to 10²⁹carat diamonds: origin of the pulsar planets

Margalit

Metzger

2016

Mon. Not. R. Astron. Soc.

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We show that the merger and tidal disruption of a C/O white dwarf (WD) by a neutron star (NS) binary companion provides a natural formation scenario for the PSR B1257+12 planetary system. Starting with initial conditions for the debris disk produced of the disrupted WD, we model its long term viscous evolution, including for the first time the effects of mass and angular momentum loss during the early radiatively inefficient accretion flow (RIAF) phase and accounting for the unusual C/O composition on the disk opacity. For plausible values of the disk viscosity α ∼ 10 −3 − 10 −2 and the RIAF mass loss efficiency, we find that the disk mass remaining near the planet formation radius at the time of solid condensation is sufficient to explain the pulsar planets. Rapid rocky planet formation via gravitational instability of the solid carbon-dominated disk is facilitated by the suppression of vertical shear instabilities due to the high solid-to-gas ratio. Additional evidence supporting a WD-NS merger scenario includes (1) the low observed occurrence rate of pulsar planets ( 1% of NS birth), comparable to the expected WD-NS merger rate; (2) accretion by the NS during the RIAF phase is sufficient to spin PSR B1257+12 up to its observed 6 ms period; (3) similar models of 'low angular momentum' disks, such as those produced from supernova fallback, find insufficient mass reaching the planet formation radius. The unusually high space velocity of PSR B1257+12 of 326 km s −1 suggests a possible connection to the Calcium-rich transients, dim supernovae which occur in the outskirts of their host galaxies and were proposed to result from mergers of WD-NS binaries receiving SN kicks. The C/O disk composition implied by our model likely results in carbon-rich planets with diamond interiors.

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The Interplay Between Chemistry and Nucleation in the Formation of Carbonaceous Dust in Supernova Ejecta

Cited by 25 publications

References 55 publications

Molecular nucleation theory of dust formation in core-collapse supernovae applied to SN 1987A

Molecular nucleation theory of dust formation in core-collapse supernovae applied to SN 1987A

Early formation of carbon monoxide in the Centaurus A supernova SN 2016adj

Merger of a white dwarf–neutron star binary to 10²⁹carat diamonds: origin of the pulsar planets

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The Interplay Between Chemistry and Nucleation in the Formation of Carbonaceous Dust in Supernova Ejecta

Cited by 25 publications

References 55 publications

Molecular nucleation theory of dust formation in core-collapse supernovae applied to SN 1987A

Molecular nucleation theory of dust formation in core-collapse supernovae applied to SN 1987A

Early formation of carbon monoxide in the Centaurus A supernova SN 2016adj

Merger of a white dwarf–neutron star binary to 1029carat diamonds: origin of the pulsar planets

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Product

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Merger of a white dwarf–neutron star binary to 10²⁹carat diamonds: origin of the pulsar planets