Very Large Interstellar Grains as Evidenced by the Mid-Infrared Extinction

Wang, Shu; Li, Aigen; Jiang, Biwei

doi:10.1088/0004-637x/811/1/38

Cited by 72 publications

(74 citation statements)

References 66 publications

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“…The IR extinction law has been investigated by many authors. An overview of the observations was given by Wang et al (2014), while an overview of the corresponding models was given by Wang et al (2015). Their comparison suggests the presence of carbon grains with a radius of more than one micron in the medium.…”

Section: Discussionmentioning

confidence: 99%

Extinction law at a distance up to 25 kpc toward the Galactic poles

Gontcharov

2016

Astron. Lett.

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characteristics and properties of the Milky Way Galaxy, interstellar medium. Photometry from the Tycho-2, 2MASS, and WISE catalogues for clump and branch giants at a distance up to 25 kpc toward the Galactic poles has allowed the variations of various characteristics of the infrared interstellar extinction law with distance to be analyzed. The results obtained by the extinction law extrapolation method are consistent for different classes of stars and different characteristics as well as with previous studies. The conventional extinction law with a low infrared extinction is characteristic of only a thin layer no farther than 100 pc from the Galactic plane and of two thin layers near Z = −600 and +500 pc. Far from the Galactic plane, in the Galactic halo, the infrared extinction law is different: the extinction in the Ks, W 1, W 2, W 3, and W 4 bands is, respectively, 0.17, 0.16, 0.16, 0.07, and 0.03 of the extinction in the V band. The accuracy of these coefficients is 0.03. If the extinction law reflects primarily the grain size distribution, then the fraction of large dust grains far from the Galactic plane is greater than that in the circumsolar interstellar medium.

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Section: Discussionmentioning

confidence: 99%

Extinction law at a distance up to 25 kpc toward the Galactic poles

Gontcharov

2016

Astron. Lett.

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“…The actual dust size distribution however could differ from the MRN one. For example, Wang, Li & Jiang (2015) reported that the existence of the very large (0.5 − 6 µm) dust grains in the ISM is confirmed by several independent observational evidences (see also Lehtinen & Mattila 1996;Pagani et al 2010;Steinacker et al 2015). Moreover, Wang et al (2015) noted that "if a substantial fraction of interstellar dust is from supernova condensates, then µm-sized grains may be prevalent in the ISM".…”

Section: Combining This Equation With Equation (1) One Hasmentioning

confidence: 92%

An astrosphere around the blue supergiant κ Cas: possible explanation of its filamentary structure

Katushkina

Alexashov

Gvaramadze

et al. 2017

Monthly Notices of the Royal Astronomical Society

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High-resolution mid-infrared observations carried out by the Spitzer Space Telescope allowed one to resolve the fine structure of many astrospheres. In particular, they showed that the astrosphere around the B0.7 Ia star κ Cas (HD 2905) has a clear-cut arc structure with numerous cirrus-like filaments beyond it. Previously, we suggested a physical mechanism for the formation of such filamentary structures. Namely, we showed theoretically that they might represent the non-monotonic spatial distribution of the interstellar dust in astrospheres (viewed as filaments) caused by interaction of the dust grains with the interstellar magnetic field disturbed in the astrosphere due to colliding of the stellar and interstellar winds. In this paper, we invoke this mechanism to explain the structure of the astrosphere around κ Cas. We performed 3D magnetohydrodynamic modelling of the astrosphere for realistic parameters of the stellar wind and space velocity. The dust dynamics and the density distribution in the astrosphere were calculated in the framework of a kinetic model. It is found that the model results with the classical MRN size distribution of dust in the interstellar medium do not match the observations, and that the observed filamentary structure of the astrosphere can be reproduced only if the dust is composed mainly of big (µm-sized) grains. Comparison of the model results with observations allowed us to estimate parameters (number density and magnetic field strength) of the surrounding interstellar medium.

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“…There has been considerable progress in the measurements of the interstellar extinction (e.g., see Valencic et al 2004) and DIBs (see Cami & Cox 2014). There is also an improved understanding of the interstellar extinction models (Weingartner & Draine 2001, Draine & Li 2007, Jones et al 2013, Wang, Li & Jiang 2015a and of the possible carrier candidates of DIBs (e.g., see Jones 2014, Omont 2016. Making use of these advances, we aim at an extensive revisit of the possible "missing link" between the UV extinction and DIBs.…”

Section: Introductionmentioning

confidence: 99%

Diffuse Interstellar Bands and the Ultraviolet Extinction Curves: The Missing Link Revisited

Xiang

Zhong

2017

ApJ

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A large number of interstellar absorption features at ∼ 4000Å-1.8 µm, known as the "diffuse interstellar bands" (DIBs), remains unidentified. Most recent works relate them to large polycyclic aromatic hydrocarbon (PAH) molecules or ultrasmall carbonaceous grains which are also thought to be responsible for the 2175Å extinction bump and/or the far ultraviolet (UV) extinction rise at λ −1 > 5.9 µm −1 . Therefore, one might expect some relation between the UV extinction and DIBs. Such a relationship, if established, could put important constraints on the carrier of DIBs. Over the past four decades, whether DIBs are related to the shape of the UV extinction curves has been extensively investigated. However, the results are often inconsistent, partly due to the inconsistencies in characterizing the UV extinction. Here we re-examine the connection between the UV extinction curve and DIBs. We compile the extinction curves and the equivalent widths of 40 DIBs along 97 slightlines. We decompose the extinction curve into three Drude-like functions composed of the visible/near-infrared component, the 2175Å bump, and the far-UV extinction at λ −1 > 5.9 µm −1 . We argue that the wavelength-integrated far-UV extinction derived from this decomposition technique best measures the strength of the far-UV extinction. No correlation is found between the far-UV extinction and most (∼ 90%) of the DIBs. We have also shown that the color excess E(1300 − 1700), the extinction difference at 1300Å and 1700Å often used to measure the strength of the far-UV extinction, does not correlate with DIBs. Finally, we confirm the earlier findings of no correlation between the 2175Å bump and DIBs or between the 2175Å bump and the far-UV extinction.

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Very Large Interstellar Grains as Evidenced by the Mid-Infrared Extinction

Cited by 72 publications

References 66 publications

Extinction law at a distance up to 25 kpc toward the Galactic poles

Extinction law at a distance up to 25 kpc toward the Galactic poles

An astrosphere around the blue supergiant κ Cas: possible explanation of its filamentary structure

Diffuse Interstellar Bands and the Ultraviolet Extinction Curves: The Missing Link Revisited

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