Interstellar Extinction and Elemental Abundances

Zuo, W. B.; Li, Aigen; Zhao, Gang

doi:10.48550/arxiv.2011.09440

Cited by 2 publications

(2 citation statements)

References 68 publications

(106 reference statements)

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“…Li (2005) showed, based on the argument on the Kramers-Kronig relations, that the observed optical-UV extinction is still underproduced with the Galactic metal abundance derived from B stars. We should also keep in mind that recent dust models with updated extinction-to-column density ratios ( / H ) and the protosolar abundance with a correction for Galactic chemical evolution after the Sun formation indicate that the above severe metallicity constraint may not be an issue any more Zuo et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Evolution of dust porosity through coagulation and shattering in the interstellar medium

Hirashita,

Il'in,

Pagani

et al. 2021

Preprint

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The properties of interstellar grains, such as grain size distribution and grain porosity, are affected by interstellar processing, in particular, coagulation and shattering, which take place in the dense and diffuse interstellar medium (ISM), respectively. In this paper, we formulate and calculate the evolution of grain size distribution and grain porosity through shattering and coagulation. For coagulation, we treat the grain evolution depending on the collision energy. Shattering is treated as a mechanism of forming small compact fragments. The balance between these processes are determined by the dense-gas mass fraction dense , which determines the time fraction of coagulation relative to shattering. We find that the interplay between shattering supplying small grains and coagulation forming porous grains from shattered grains is fundamentally important in creating and maintaining porosity. The porosity rises to 0.7-0.9 (or the filling factor 0.3-0.1) around grain radii ∼ 0.1 m. We also find that, in the case of dense = 0.1 (very efficient shattering with weak coagulation) porosity significantly enhances coagulation, creating fluffy submicron grains with filling factors lower than 0.1. The porosity enhances the extinction by 10-20 per cent at all wavelengths for amorphous carbon and at ultraviolet wavelengths for silicate. The extinction curve shape of silicate becomes steeper if we take porosity into account. We conclude that the interplay between shattering and coagulation is essential in creating porous grains in the interstellar medium and that the resulting porosity can impact the grain size distributions and extinction curves.

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Section: Introductionmentioning

confidence: 99%

Evolution of dust porosity through coagulation and shattering in the interstellar medium

Hirashita,

Il'in,

Pagani

et al. 2021

Preprint

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“…(6) Here, we assume that all Si and Fe atoms, and 70 percent of carbon atoms are locked up in dust. For the iron oxides, we also assume that Fe atoms are equally shared among the three different iron oxides (Zuo et al 2020). The F factors for graphite, silicates, iron, and iron oxides are listed in Table 8 of Zuo et al (2020).…”

Section: Metallicity Inferred From the Kramers-kronig Relationmentioning

confidence: 99%

Constraining the Metallicities of Damped Lyα Systems Using Extinction Curves

Fathivavsari

2021

ApJ

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In this paper, we present a new method to constrain the metallicities of high redshift damped Ly α (DLA) absorbers using observed extinction curves. This is the first time such an approach is employed to constrain the metallicities of extragalactic absorbers. To demonstrate our method, we use the spectra of 13 quasars and one GRB with DLA absorbers detected along their sightlines. By using the Kramers-Kronig (KK) relation, which relates the wavelength-integrated extinction to the total volume occupied by dust per hydrogen nucleon, we set some robust lower limits on the metallicity of the DLAs. The resulting lower limits are all consistent with the DLA metallicities from the literature. The GRB extinction curve exhibits a very strong 2175 Å extinction bump. We try to constrain the metallicity of the GRB DLA by modeling the GRB extinction curve using dust models with two (graphite and silicates) and three (PAH, hydrogenated amorphous carbon, and silicates) dust components. The two-component model resulted in a metallicity of Z ∼ −0.45 while the threecomponent model gives Z ∼ −0.50. On the other hand, the lower limit from the KK approach for this DLA is Z ≥ −0.60. Modeling a large sample of extinction curves with 2175 Å extinction bump and measured DLA metallicities would allow a thorough comparison between the KK and the modeldependent approach. In cases where the precise measurement of the metallicity of a DLA is not possible (e.g. due to the saturation of important absorption lines), the approach presented in this paper can be used to constrain the metallicity.

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Interstellar Extinction and Elemental Abundances

Cited by 2 publications

References 68 publications

Evolution of dust porosity through coagulation and shattering in the interstellar medium

Evolution of dust porosity through coagulation and shattering in the interstellar medium

Constraining the Metallicities of Damped Lyα Systems Using Extinction Curves

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