FORMATION OF DUST IN THE EJECTA OF TYPE Ia SUPERNOVAE

Nozawa, Takaya; Maeda, Keiichi; Kozasa, Takashi; Tanaka, Masaomi; Nomoto, Ken’ichi; Umeda, Hideyuki

doi:10.1088/0004-637x/736/1/45

Cited by 92 publications

(91 citation statements)

References 104 publications

(173 reference statements)

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“…Furthermore, the abundance and growth of the grains in SN Ia ejecta is greatly impeded by the large abundance of radioactive 56 Ni, which produces fast electrons and γ-rays that are effective at dissociating precursor molecules in this environment. Models for the formation of dust in SN Ia show that any dust that forms will have small radii (<100 Å), and will probably be totally destroyed by the reverse shock, which is generated as the ejecta is decelerated by the ambient ISM (Nozawa et al 2011). The models produced no significant amount of iron dust.…”

Section: Evidence For the Absence Of Dust In Sn Ia Ejectamentioning

confidence: 99%

Iron: A Key Element for Understanding the Origin and Evolution of Interstellar Dust

Dwek

2016

ApJ

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The origin and depletion of iron differ from all other abundant refractory elements that make up the composition of interstellar dust. Iron is primarily synthesized in Type Ia supernovae (SNe Ia) and in core collapse supernovae (CCSN), and is present in the outflows from AGB stars. Only the latter two are observed to be sources of interstellar dust since searches for dust in SN Ia have provided strong evidence for the absence of any significant mass of dust in their ejecta. Consequently, more than 65% of the iron is injected into the ISM in gaseous form. Yet ultraviolet and X-ray observations along many lines of sight in the ISM show that iron is severely depleted in the gas phase as compared to expected solar abundances. The missing iron, comprising about 90% of the total, is believed to be locked up in interstellar dust. This suggests that most of the missing iron must have precipitated from the ISM gas by a cold accretion onto preexisting silicate, carbon, or composite grains. Iron is thus the only element that requires most of its growth to occur outside the traditional stellar condensation sources. This is a robust statement that does not depend on our evolving understanding of the dust destruction efficiency in the ISM. Reconciling the physical, optical, and chemical properties of such composite grains with their many observational manifestations is a major challenge for understanding the nature and origin of interstellar dust.

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Section: Evidence For the Absence Of Dust In Sn Ia Ejectamentioning

confidence: 99%

Iron: A Key Element for Understanding the Origin and Evolution of Interstellar Dust

Dwek

2016

ApJ

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“…Indeed, models suggest dust can form in SNe Ia at these velocities, timescales, and total mass (Nozawa et al 2011). Furthermore, SNe Iax are defined by their low velocities (e.g., Foley et al 2013, and references within).…”

Section: The Source Of the Mid-ir Emissionmentioning

confidence: 99%

AN EXCESS OF MID-INFRARED EMISSION FROM THE TYPE Iax SN 2014dt

Fox

Johansson

Kasliwal

et al. 2015

ApJL

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Supernovae Type Iax (SNe Iax) are less energetic and less luminous than typical thermonuclear explosions. A suggested explanation for the observed characteristics of this subclass is a binary progenitor system consisting of a CO white dwarf primary accreting from a helium star companion. A single-degenerate explosion channel might be expected to result in a dense circumstellar medium (CSM), although no evidence for such a CSM has yet been observed for this subclass. Here we present recent Spitzerobservations of the SN Iax 2014dt obtained by the SPIRITS program nearly one year post-explosion that reveal a strong mid-IR excess over the expected fluxes of more normal SNe Ia. This excess is consistent with 10 −5 M  of newly formed dust, which would be the first time that newly formed dust has been observed to form in a Type Ia. The excess, however, is also consistent with a dusty CSM that was likely formed in pre-explosion mass-loss, thereby suggesting a single degenerate progenitor system. Compared to other SNe Ia that show significant shock interaction (SNe Ia-CSM) and interacting corecollapse events (SNe IIn), this dust shell in SN 2014dt is less massive. We consider the implications that such a pre-existing dust shell has for the progenitor system, including a binary system with a mass donor that is a red giant, a red supergiant, or an asymptotic giant branch star.

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“…The formation process of dust in the SN ejecta has been studied mainly with the classical nucleation theory and its extension (Kozasa et al 1989(Kozasa et al , 1991Todini & Ferrara 2001;Nozawa et al 2003Nozawa et al , 2008Nozawa et al , 2010Nozawa et al , 2011Bianchi & Schneider 2007). In the nucleation theory, the condensation of dust is described by the formation of stable seed nuclei (called critical clusters) and their growth, where the formation rate of critical clusters is derived by assuming the nucleation current to be in a steady state.…”

Section: Introductionmentioning

confidence: 99%

Formulation of Non-Steady-State Dust Formation Process in Astrophysical Environments

Nozawa¹,

Kozasa²

2013

ApJ

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The non-steady-state formation of small clusters and the growth of grains accompanied by chemical reactions are formulated under the consideration that the collision of key gas species (key molecule) controls the kinetics of dust formation process. The formula allows us to evaluate the size distribution and condensation efficiency of dust formed in astrophysical environments. We apply the formulation to the formation of C and MgSiO 3 grains in the ejecta of supernovae, as an example, to investigate how the non-steady effect influences the formation process, condensation efficiency f con,∞ , and average radius a ave,∞ of newly formed grains in comparison with the results calculated with the steady-state nucleation rate. We show that the steady-state nucleation rate is a good approximation if the collision timescale of key molecule τ coll is much smaller than the timescale τ sat with which the supersaturation ratio increases; otherwise the effect of the nonsteady state becomes remarkable, leading to a lower f con,∞ and a larger a ave,∞ . Examining the results of calculations, we reveal that the steady-state nucleation rate is applicable if the cooling gas satisfies Λ ≡ τ sat /τ coll 30 during the formation of dust, and find that f con,∞ and a ave,∞ are uniquely determined by Λ on at the onset time t on of dust formation. The approximation formulae for f con,∞ and a ave,∞ as a function of Λ on could be useful in estimating the mass and typical size of newly formed grains from observed or model-predicted physical properties not only in supernova ejecta but also in mass-loss winds from evolved stars.

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FORMATION OF DUST IN THE EJECTA OF TYPE Ia SUPERNOVAE

Cited by 92 publications

References 104 publications

Iron: A Key Element for Understanding the Origin and Evolution of Interstellar Dust

Iron: A Key Element for Understanding the Origin and Evolution of Interstellar Dust

AN EXCESS OF MID-INFRARED EMISSION FROM THE TYPE Iax SN 2014dt

Formulation of Non-Steady-State Dust Formation Process in Astrophysical Environments

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