Interstellar scintillation of radio sources as a probe for investigations of the local interstellar medium

Bochkarev, N. G.; Ryabov, M. I.

doi:10.1007/bfb0104722

Cited by 3 publications

(8 citation statements)

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“…In the most widespread media, the extinction maximum in a region of space occurs at a wavelength that coincides in order of magnitude with the mean dust grain diameter in this region (Bochkarev 2010). For example, the commonly considered extinction A V in the photometric V band with a wavelength of 0.55 microns and, in general, the visual extinction is produced predominantly by submicron sized dust grains, whereas the infrared (IR) one is produced by supermicron ones.…”

Section: Introductionmentioning

confidence: 99%

Some properties of dust outside the galactic disk

Gontcharov

2013

Astron. Lett.

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Pulkovo Astronomical Observatory, Russian Academy of Sciences, Pulkovskoe sh. 65, St. Petersburg, 196140 Russia Key words: interstellar dust grains; color-magnitude diagrams, giant and subgiant starsThe joint use of accurate near-and mid-infrared photometry from the 2MASS and WISE catalogues has allowed the variations of the extinction law and the dust grain size distribution in high Galactic latitudes (|b| > 50• ) at distances up to 3 kpc from the Galactic midplane to be analyzed. The modified method of extrapolation of the extinction law applied to clump giants has turned out to be efficient for separating the spatial variations of the sample composition, metallicity, reddening, and properties of the medium. The detected spatial variations of the coefficients E (H−W 1) /E (H−Ks) , E (H−W 2) /E (H−Ks) , and E (H−W 3) /E (H−Ks) are similar for all high latitudes and depend only on the distance from the Galactic midplane. The ratio of short-wavelength extinction to long-wavelength one everywhere outside the Galactic disk has been found to be smaller than that in the disk and, accordingly, the mean dust grain size is larger, while the grain size distribution in the range 0.5 − 11 microns is shifted toward coarse dust. Specifically, the mean grain size initially increases sharply with distance from the Galactic midplane, then decreases gradually, approaching a value typical of the disk at |Z| ≈ 2.4 kpc, and, further out, stabilizes or may increase again. The coefficients under consideration change with coordinate Z with a period of about 1312 ± 40 pc, coinciding every 656 ± 20 pc to the south and the north and showing a significant anticorrelation between their values * E-mail: georgegontcharov@yahoo.com 1 in the southern and northern hemispheres at intermediate Z. Thus, there exists a unified large-scale periodic structure of the interstellar medium at high latitudes within at least 5 kpc. The same periodic variations have also been found for the extinction coefficient R V within 600 pc of the Galactic midplane through the reduction of different photometric data for stars of different classes. 2 INTRODUCTIONThe wavelength dependence of interstellar extinction (extinction law) is related primarily to the dust grain size distribution in the absorbing medium. In the most widespread media, the extinction maximum in a region of space occurs at a wavelength that coincides in order of magnitude with the mean dust grain diameter in this region (Bochkarev 2010). For example, the commonly considered extinction A V in the photometric V band with a wavelength of 0.55 microns and, in general, the visual extinction is produced predominantly by submicron sized dust grains, whereas the infrared (IR) one is produced by supermicron ones. Conclusions about the physical properties of dust in the region of space under consideration and about the contribution of dust to the total mass of the matter can be reached by studying the wavelength dependence of extinction. Conversely, the extinction can be calculated by studying the properti...

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Section: Introductionmentioning

confidence: 99%

Some properties of dust outside the galactic disk

Gontcharov

2013

Astron. Lett.

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“…As shown before, the bulk of the mass of interstellar dust clearly is contained in dust particles that cause extinction in the 0.6 − 5 µm range (in the WD2001 model with R V = 5.5, at 1.5 µm). Within this range, n ′ ≈ 1 (Bochkarev, 2009). But n ′′ varies over wide limits, for example from n ≪ 1 for water ice to n ′′ ≈ 1 for carbon (Bohren and Huffman, 1986).…”

Section: Dust Inside and Outside The Solar Systemmentioning

confidence: 88%

“…According to modern ideas, dust is formed in the shells of red giants, supergiants, novae and supernovae and is transported from them into the interstellar medium (Bochkarev (2009)). But for a long time, observational data on the dust mass produced this way differed by several orders of magnitude from theoretical estimates ).…”

Section: Coarse Dust Outside the Galactic Diskmentioning

confidence: 99%

“…For R V = 5.5, the maximum of the WD2001 distribution at 3·10 −27 g/cm 3 applies to grains with a mass of 2 · 10 −13 g, i.e., a radius of 0.25 µm. Carbon grains of this size have maximal extinction at 1.5 µm (Bohren and Huffman, 1986;Bochkarev, 2009). But if the grains consist predominantly of water ice and have an average density of 1 g/cm 3 , the peak extinction wavelength over the size distribution of the grains is different.…”

Section: Dust Inside and Outside The Solar Systemmentioning

confidence: 99%

“…They are described by the real n ′ and imaginary n ′′ parts of the complex refractive index n = n ′ − i · n ′′ . n ′ and n ′′ can be complicated functions of λ that depend on chemical composition and other characteristics of dust particles (Bochkarev, 2009). As shown before, the bulk of the mass of interstellar dust clearly is contained in dust particles that cause extinction in the 0.6 − 5 µm range (in the WD2001 model with R V = 5.5, at 1.5 µm).…”

Section: Dust Inside and Outside The Solar Systemmentioning

confidence: 99%

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Interstellar extinction

AccessScience

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Key words: interstellar extinction: reddening: interstellar dust particles: characteristics and properties of the Milky Way galaxy.This review describes our current understanding of interstellar extinction. This differ substantially from the ideas of the 20th century. With infrared surveys of hundreds of millions of stars over the entire sky, such as 2MASS, SPITZER-IRAC, and WISE, we have looked at the densest and most rarefied regions of the interstellar medium at distances of a few kpc from the sun. Observations at infrared and microwave wavelengths, where the bulk of the interstellar dust absorbs and radiates, have brought us closer to an understanding of the distribution of the dust particles on scales of the Galaxy and the Universe. We are in the midst of a scientific revolution in our understanding of the interstellar medium and dust. Progress in, and the key results of, this revolution are still difficult to predict. Nevertheless, (a) a physically justified model has been developed for the spatial distribution of absorbing material over the nearest few kiloparsecs, including the Gould belt as a dust container, which gives an accurate estimate of the extinction for any object just in terms of its galactic coordinates. It is also clear that (b) the interstellar medium makes up roughly half the mass of matter in the galactic vicinity of the solar system (the other half is made up of stars, their remnants, and dark matter) and (c) the interstellar medium and, especially, dust, differ substantially in different regions of space, and deep space cannot be understood by only studying nearby space. *

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Explosive magnetic hypothesis of the Galaxy spiral structure in the history of the Earth.

Raf

2023

Preprint

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The possibility of the formation of a triplet six-armed spiral structure of the Galaxy as a result of the impact on the stellar population of the Milky Way disk of concentrated ionized explosive supernova ejections (with different velocity extrema) from the central region is considered. A mechanism is proposed for concentration and acceleration by the magnetic field of the Galaxy R<3-5 kpc of ionized gas and dust emissions, with their further canalization along the magnetic axis of the dipole of a close binary system of supermassive objects at R<0.1 kpc, rotating with acceleration. The hypothesis is confirmed by the periodicity of pulses of electrically conductive cosmic dust entering the Earth, as well as by the presence of anisotropies of ultrahigh-energy cosmic rays >1014eV from the calculated directions. Thus, the triplet view of the boundaries of the geochronological scale is substantiated as the consequences of different-scale effects of heterogeneities in the triplet structure of the Spiral arms.

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Interstellar scintillation of radio sources as a probe for investigations of the local interstellar medium

Cited by 3 publications

References 6 publications

Some properties of dust outside the galactic disk

Some properties of dust outside the galactic disk

Interstellar extinction

Explosive magnetic hypothesis of the Galaxy spiral structure in the history of the Earth.

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