Dust Mass Research Articles

Infrared Ejecta and Cold Dust in the Young Supernova Remnant N132D

We present Spitzer, Wide-field Infrared Survey Explorer (WISE), and Herschel observations of the young supernova remnant (SNR) N132D in the Large Magellanic Cloud, including 3–40 μm Spitzer Infrared Spectrograph (IRS) mapping, 12 μm WISE and 70, 100, 160, 250, 350, and 500 μm Herschel images. The high-velocity lines of [Ne ii] at 12.8 μm, [Ne iii] at 15.5 μm, and [O iv] 26 μm reveal infrared ejecta concentrated in a central ring and coincide with the optical and X-ray ejecta. Herschel images reveal far-IR emission coinciding with the central ejecta, which suggests that the IR emission is freshly formed, cold dust in the SN ejecta. The infrared spectra are remarkably similar to those of another young SNR of 1E0102 with Ne and O lines. Shock modeling of the Ne ejecta emission suggests a gas temperature of 300–600 K and densities in the range 1000–2 × 104 cm−3 in the postshock photoionized region. The IR continuum from the ejecta shows an 18 μm peak dust feature. We performed spectral fitting to the IRS dust continuum and Herschel photometry. The dust mass associated with the central ejecta is 1.25 ± 0.65 M ⊙, while the 18 μm dust feature requires forsterite grains. The dust mass of the central ejecta region in N132D is higher than those of other young SNRs, which is likely associated with its higher progenitor mass. We discuss the dust productivity in the ejecta of N132D and infer its plausible implications for dust in the early universe.

New constraints on the presence of debris disks around G 196-3 B and VHS J125601.92–125723.9 b

Context. The existence of warm (protoplanetary) disks around very young isolated planetary and brown dwarf mass objects is known based on near- and mid-infrared flux excesses and millimeter observations. These disks may later evolve into debris disks or rings, although none have been observed or confirmed so far. Little is known about circum(sub)stellar and debris disks around substellar objects. Aims. We aim to investigate the presence of debris disks around two of the closest (~20 pc), young substellar companions, namely G196-3 B and VHS J125601.92–125723.9 b (VHS J1256–1257 b), whose masses straddle the borderline between planets and brown dwarfs. Both are companions at wide orbits (≥100 au) of M-type dwarfs and their ages (50–100 Myr and 150–300 Myr, respectively) are thought to be adequate for the detection of second-generation disks. Methods. We obtained deep images of G196-3 B and VHS J1256–1257 b with the NOrthern Extended Millimeter Array (NOEMA) at 1.3 mm. These data were combined with recently published Atacama Large Millimeter Array (ALMA) and Very Large Array (VLA) data of VHS J1256–1257 b at 0.87 mm and 0.9 cm, respectively. Results. Neither G196-3 B nor VHS J1256–1257 b were detected in the NOEMA, ALMA, and VLA data. At 1.3 mm, we imposed flux upper limits of 0.108 mJy (G196-3 B) and 0.153 mJy (VHS J1256–1257 b) with a 3-σ confidence. Using the flux upper limits at the millimeter and radio wavelength regimes, we derived maximum values of 1.38×10−2 MEarth and 5.46 × 10−3 MEarth for the mass of any cold dust that might be surrounding G196-3 B and VHS J1256–1257 b, respectively. Conclusions. We put our results in the context of other deep millimeter observations of free-floating and companion objects with substellar masses smaller than 20 MJup and ages between approximately one and a few hundred million years. Only two very young (2–5.4 Myr) objects are detected out of a few tens of them. This implies that the disks around these very low-mass objects must have small masses, and possibly reduced sizes, in agreement with findings by other groups. If debris disks around substellar objects scale down (in mass and size) in a similar manner as protoplanetary disks do, millimeter observations of moderately young brown dwarfs and planets must be at least two orders of magnitude deeper to be able to detect and characterize their surrounding debris disks.

Near-infrared and Optical Observations of Type Ic SN 2021krf: Luminous Late-time Emission and Dust Formation

We present near-infrared (NIR) and optical observations of the Type Ic supernova (SN Ic) SN 2021krf obtained between days 13 and 259 at several ground-based telescopes. The NIR spectrum at day 68 exhibits a rising K-band continuum flux density longward of ∼2.0 μm, and a late-time optical spectrum at day 259 shows strong [O i] 6300 and 6364 Å emission-line asymmetry, both indicating the presence of dust, likely formed in the SN ejecta. We estimate a carbon-grain dust mass of ∼2 × 10−5 M ⊙ and a dust temperature of ∼900–1200 K associated with this rising continuum and suggest the dust has formed in SN ejecta. Utilizing the one-dimensional multigroup radiation-hydrodynamics code STELLA, we present two degenerate progenitor solutions for SN 2021krf, characterized by C–O star masses of 3.93 and 5.74 M ⊙, but with the same best-fit 56Ni mass of 0.11 M ⊙ for early times (0–70 days). At late times (70–300 days), optical light curves of SN 2021krf decline substantially more slowly than those expected from 56Co radioactive decay. Lack of H and He lines in the late-time SN spectrum suggests the absence of significant interaction of the ejecta with the circumstellar medium. We reproduce the entire bolometric light curve with a combination of radioactive decay and an additional powering source in the form of a central engine of a millisecond pulsar with a magnetic field smaller than that of a typical magnetar.

Dust properties around NGC 7023 nebula in interstellar medium using IRIS, AKARI, and WISE survery


 
 
 
 We have studied the physical properties of dust around the nebula NGC 7023. The physical properties have been studied at 60 μm and 100 μm in the IRIS survey, 90 μm and 140 μm in the AKARI survey, and 12 μm and 22 μm in the WISE survey at the right ascension (R.A.) (J2000) = 21h01m35.60s, declination (J2000) = + 68o10m10.0s. The nebula is found at a distance of 335.82 pc from us. We found the dust color temperature is in the range between 36.19 K ± 0.03 K to 24.49 K ± 0.03 K with an average dust color temperature of 28.24 K ± 0.03 K in IRIS survey and a range between 38.80 K ± 0.25 K to 21.00 K ± 0.25 K with an average dust color temperature 26.39 K ± 0.25 K in AKARI survey. Similarly, in WISE, the dust color temperature was found in the range between 130.92 K ± 0.01 K to 88.71 K ± 0.01 K with an average of 104.76 K ± 0.25 K. The temperature in WISE is higher than that of the IRIS and AKARI survey. We have also calculated the dust mass, whose average value was found to be 1.18 x 1027 kg (5.93 x 10−4 M⊙) in IRIS, 1.06 x 1028 kg (5.33 x 10−3 M⊙) in AKARI, and 1.06 x 1027 kg (5.33 x 10−4 M⊙) in the WISE survey. We have also studied the visual extinction parameter due to such dust in infrared bands. This work will contribute to understanding infrared band emission from the dusty region around the nebular structure in the interstellar medium.
 
 
 

Simulated Observations of Star Formation Regions: Infrared Evolution of Globally Collapsing Clouds

A direct comparison between hydrodynamical simulations and observations is needed to improve the physics included in the former and to test biases in the latter. Post-processing radiative transfer and synthetic observations are now the standard way to do this. We report on the first application of the SKIRT radiative-transfer code to simulations of a star-forming cloud. The synthetic observations are then analyzed following traditional observational workflows. We find that in the early stages of the simulation, stellar radiation is inefficient in heating dust to the temperatures that are observed in Galactic clouds, thus the addition of an interstellar radiation field is necessary. The spectral energy distribution of the cloud settles rather quickly after ∼3 Myr of evolution from the onset of star formation, but its morphology continues to evolve for ∼8 Myr due to the expansion of H ii regions and the respective creation of cavities, filaments, and ridges. Modeling synthetic Herschel fluxes with one- or two-component modified blackbodies underestimates total dust masses by a factor of ∼2. However, spatially resolved fitting recovers up to about 70% of the intrinsic value. This “missing mass” is located in a very cold dust component with temperatures below 10 K, which does not contribute appreciably to the far-infrared flux. This effect could bias real observations if this dust exists in large amounts. Finally, we tested observational calibrations of the SFR based on infrared fluxes and concluded that they are in agreement when compared to the intrinsic SFR of the simulation averaged over ∼100 Myr.

Cosmic Sands: The Origin of Dusty, Star-forming Galaxies in the Epoch of Reionization

We present the Cosmic Sands suite of cosmological zoom-in simulations based on the simba galaxy formation model in order to study the buildup of the first massive and dusty galaxies in the early universe. Residing in the most massive halos, we find that the compact proto-massive galaxies undergo nearly continuous mergers with smaller subhalos, boosting star formation rates (SFRs) and the buildup of stellar mass. The galaxies are already appreciably chemically evolved by z = 7, with modeled dust masses comparable to those inferred from observations in the same epoch, except for the most extreme systems. We track gas accretion onto the galaxies to understand how extreme SFRs can be sustained by these early systems. We find that smooth gas accretion can maintain SFRs above 250 M ⊙ yr−1, but to achieve SFRs that boost galaxies well above the main sequence, a larger perturbation like a gas-rich major merger is necessary to trigger a starburst episode. Post-processing the Cosmic Sands simulations with dust RT, we find that, while the infrared luminosities of the most-dust-rich galaxies are comparable to local ULIRGs, they are substantially dimmer than classical z = 2 submillimeter galaxies. We end with a discussion on the possible reasons for this discrepancy at the highest masses and the future work we intend to carry out to study the chemical enrichment of the earliest dusty galaxies.

Energy output characteristics and safety design of Al-AlH3 composite dust for energetic material additive

Aluminum (Al) is the most widely used metal additive in energetic materials, but its application is limited due to its oxidizable nature. However, aluminum hydride (AlH3) could disrupt the oxide film structure and improve applications of the Al additive in energetic materials by releasing hydrogen. Therefore, this paper explored the explosion characteristics of the Al-AlH3 composite dust by conducting composite dust explosion venting experiments. The influences of composite dust concentrations and mass ratios on the explosion pressure and flame were evaluated. The consequences indicated that when the composite dust concentration was constant, the explosion pressure and the reduction rate of explosion pressure gradually decreased as increasing the mass ratio, which confirmed that the explosion intensity of AlH3 was greater than that of Al. When the composite dust mass ratio was the same, the increase in dust concentration caused the explosion pressure, the pressure rise rate, the flame front propagation distance, and velocity to increase first and then attenuate. 750 g/m3 was the best dust explosion concentration. On this basis, the safety design applicability of composite dust was conducted based on the NFPA 68 explosion venting design standard, which was verified to be suitable for Al dust. Notably, the safety margin should be taken into account when carrying out a safety design for composite dust using NFPA 68. In the paper, the composite dust explosion characteristics were obtained through experiments and mechanism analysis, which provided data support for the research of Al-AlH3 composite dust for energetic material additives.

An empirical study of dust properties at the earliest epochs

ABSTRACT We present an empirical analysis of the properties of dust-continuum emission in a sample of 17 galaxies in the early Universe (4 < z < 8) with well-sampled far-infrared spectral energy distributions (SEDs) compiled from the literature. We place our results into context by self-consistently comparing to samples of nearby star-forming galaxies, luminous infrared galaxies (LIRGs), and quasars. With the exception of two sources, we find no significant evolution in the dust emissivity index across cosmic time, measuring a consistent value of βIR = 1.8 ± 0.3 at z > 4, suggesting that the effective dust properties do not change dramatically for most galaxies. Despite having comparable stellar masses, we find the high-redshift galaxies to be similar to, or even more extreme than, LIRGs in the Herschel (U)LIRG Survey, where (U)LIRG refers to (ultra-)LIRG, sample in terms of dust temperature ($T_\text{dust} \gt 40 \, \mathrm{K}$) and infrared (IR) luminosity ($L_\text{IR} \gt 10^{11} \, \mathrm{L_\odot }$). We find that the dust temperature evolves mildly towards high redshift, though the LIRGs and quasars exhibit elevated temperatures indicating a more efficient and/or additional heating mechanism. Where available, we compare stellar mass estimates to our inferred dust masses, whose degeneracy with dust temperature can only be mitigated with a well-constrained SED. In merely half of the cases, the dust yield may be explained by supernovae alone, with four sources ($44{{\ \rm per\ cent}}$) significantly exceeding a highly optimistic yield where Mdust ≈ 0.01M*. We discuss possible explanations for this apparent inconsistency and potential observational biases in the measurements of the dust properties of high-redshift galaxies, including in the current IR-bright sample.

Laser Attenuation and Ranging Correction in the Coal Dust Environment Based on Mie Theory and Phase Ranging Principle

The inadequate ventilation and complex environments in underground coal mines lead to a high concentration of dust particles. As a result, the health of the miners and the accuracy of laser rangefinder measurements are endangered. It is crucial to enhance the laser rangefinder’s efficiency to mitigate health risks and reduce labor intensity. In this study, we propose a laser power attenuation model and a ranging correction model to address the issues of laser power attenuation and inaccurate ranging in coal dust environments. The proposed models are based on theoretical analysis and practical experiments, and both are dependent on the dust particle size (<250 μm) and mass concentration. Firstly, we assessed the factors that caused laser power attenuation and demonstrated that our proposed model could accurately predict them (maximum residual of 0.06). Secondly, we obtained the connection between the attenuation coefficient and dust concentration by applying the Lambert–Beer law. Lastly, we established the ranging correction model by collecting laser wavelength information. The outcomes show that the root mean square error of the corrected values ranges between 0.27 and 0.47 mm. To summarize, our suggested model and correction technique can efficiently enhance the precision of laser rangefinder measurements, thus improving underground work in coal mines.

Observed dust surface density across cosmic times

ABSTRACT Our ability to interpret observations of galaxies and trace their stellar, gas, and dust content over cosmic time critically relies on our understanding of how the dust abundance and properties vary with environment. Here, we compute the dust surface density across cosmic times to put novel constraints on simulations of the build-up of dust. We provide observational estimates of the dust surface density consistently measured through depletion methods across a wide range of environments, going from the Milky Way up to z = 5.5 galaxies. These conservative measurements provide complementary estimates to extinction-based observations. In addition, we introduce the dust surface density distribution function – in analogy with the cold gas column density distribution functions. We fit a power law of the form log f(ΣDust) = −1.92 × log ΣDust − 3.65, which proves slightly steeper than that for neutral gas and metal absorbers. This observed relation, which can be computed by simulations predicting resolved dust mass functions through 2D projection, provides new constraints on modern dust models.

Disc population synthesis: Decrease in the solid mass reservoir through pebble drift

Surveys of star-forming regions reveal that the dust mass of protoplanetary discs decreases by several orders of magnitude on timescales of a few million years. This decrease in the mass budget of solids is likely due to the radial drift of millimetre (mm) sized solids, called pebbles, induced by gas drag. However, quantifying the evolution of this dust component in young stellar clusters is difficult due to the inherent large spread in stellar masses and formation times. Therefore, we aim to model the collective evolution of a cluster to investigate the effectiveness of radial drift in clearing the discs of mm-sized particles. We use a protoplanetary disc model that provides a numerical solution for the disc formation, as well as the viscous evolution and photoevaporative clearing of the gas component, while also including the drift of particles limited in size by fragmentation. We find that discs are born with dust masses between 50 M⊕ and 1000 M⊕, for stars with masses, respectively, between 0.1 M⊙ and 1 M⊙. The majority of this initial dust reservoir is typically lost through drift before photoevaporation opens a gap in the gas disc for models both with and without strong X-ray-driven mass-loss rates. We conclude that the decrease in time of the mass locked in fragmentation-limited pebbles is consistent with the evolution of dust masses and ages inferred from nearby star-forming regions, when assuming viscous evolution rates corresponding to mean gas disc lifetimes between 3 Myr and 8 Myr.

Morphology of the gas-rich debris disk around HD 121617 with SPHERE observations in polarized light

Context. Debris disks are the signposts of collisionally eroding planetesimal circumstellar belts, whose study can put important constraints on the structure of extrasolar planetary systems. The best constraints on the morphology of such disks are often obtained from spatially resolved observations in scattered light. In this paper, we investigate the young (~16 Myr) bright gas-rich debris disk around HD 121617. Aims. We use new scattered light observations from VLT/SPHERE to characterize the morphology and the dust properties of the debris disk. From these properties, we can then derive constraints on the physical and dynamical environment of this system, for which significant amounts of gas have been detected. Methods. The disk morphology is constrained by linear polarimetric observations in the J band. Based on our modeling results and archival photometry, we also model the spectral energy distribution (SED) to put constraints on the total dust mass and dust size distribution. Finally, we explore different scenarios that could explain these new constraints. Results. We present the first resolved image in scattered light of the debris disk around HD 121617. We fit the morphology of the disk, finding a semi-major axis of 78.3 ± 0.2 au, an inclination of 43.1 ± 0.2°, and a position angle of the major axis with respect to north of 239.8 ± 0.3°, which is compatible with the previous continuum and CO detection with ALMA. Our analysis shows that the disk has a very sharp inner edge, possibly sculpted by a yet-undetected planet or gas drag. While less sharp, its outer edge is steeper than expected for an unperturbed disk, which could also be due to a planet or gas drag, but future observations probing the system farther from the main belt would help explore this possibility further. The SED analysis leads to a dust mass of 0.21 ± 0.02 M⊕ and a minimum grain size of 0.87 ± 0.12 μm, smaller than the blowout size by radiation pressure, which is not unexpected for very bright collisionally active disks.

The ALMA view of MP Mus (PDS 66): A protoplanetary disk with no visible gaps down to 4 au scales

Aims. We aim to characterize the protoplanetary disk around the nearby (d ~ 100 pc), young solar analog MP Mus (PDS 66) and to reveal any signs of planets or ongoing planet formation in the system. Methods. We present new ALMA observations of MP Mus at 0.89 mm, 1.3 mm, and 2.2 mm with angular resolutions of ~1″, 0.05″, and 0.25″, respectively. These data probe the dust and gas in the disk with unprecedented detail and sensitivity. Results. The disk appears smooth down to the 4 au resolution of the 1.3 mm observations, in contrast with most disks observed at comparable spatial scales. The dust disk has a radius of 60±5 au, a dust mass of 0.14-0.06+0.11 MJup, and a millimeter spectral index <2 in the inner 30 au, suggesting optically thick emission from grains with a high albedo in this region. Several molecular gas lines are also detected extending up to 130±15 au, similar to small grains traced by scattered light observations. Comparing the fluxes of different CO isotopologues with previous models yields a gas mass of 0.1–1 MJup, implying a gas-to-dust ratio of 1–10. We also measured a dynamical stellar mass of Mdyn = 1.30±0.08 M⊙ and derived an age of 7–10 Myr. Conclusions. The survival of large grains in an evolved disk without gaps or rings is surprising, and it is possible that existing substructures remain undetected due to optically thick emission at 1.3 mm. Alternatively, small structures may still remain unresolved with the current observations. Based on simple scaling relations for gap-opening planets and gap widths, this lack of substructures places upper limits to the masses of planets in the disk as low as 2 M⊕−0.06 MJup at r > 40 au. The lack of millimeter emission at radii r > 60 au also suggests that the gap in scattered light between 30 and 80 au is likely not a gap in the disk density, but a shadow cast by a puffed-up inner disk.

The Rest-frame Submillimeter Spectrum of High-redshift, Dusty, Star-forming Galaxies from the SPT-SZ Survey

We present the average rest-frame spectrum of the final catalog of dusty star-forming galaxies (DSFGs) selected from the South Pole Telescope's SPT-SZ survey and measured with Band 3 of the Atacama Large Millimeter/submillimeter Array. This work builds on the previous average rest-frame spectrum, given in Spilker et al. (2014) for the first 22 sources, and is comprised of a total of 78 sources, normalized by their respective apparent dust masses. The spectrum spans 1.9 < z < 6.9 and covers rest-frame frequencies of 240–800 GHz. Combining this data with low-J CO observations from the Australia Telescope Compact Array, we detect multiple bright line features from 12CO, [C i], and H2O, as well as fainter molecular transitions from 13CO, HCN, HCO+, HNC, CN, H2O+, and CH. We use these detections, along with limits from other molecules, to characterize the typical properties of the interstellar medium (ISM) for these high-redshift DSFGs. We are able to divide the large sample into subsets in order to explore how the average spectrum changes with various galaxy properties, such as effective dust temperature. We find that systems with hotter dust temperatures exhibit differences in the bright 12CO emission lines, and contain either warmer and more excited dense gas tracers or larger dense gas reservoirs. These observations will serve as a reference point to studies of the ISM in distant luminous DSFGs (L IR > 1012 L ⊙), and will inform studies of chemical evolution before the peak epoch of star formation at z = 2–3.

An SMA Survey of Chemistry in Disks Around Herbig AeBe Stars

Protoplanetary disks around Herbig AeBe stars are exciting targets for studying the chemical environments where giant planets form. Save for a few disks, however, much of Herbig AeBe disk chemistry is an open frontier. We present a Submillimeter Array ∼213–268 GHz pilot survey of millimeter continuum CO isotopologs and other small molecules in disks around five Herbig AeBe stars (HD 34282, HD 36112, HD 38120, HD 142666, and HD 144432). We detect or tentatively detect 12CO 2–1 and 13CO 2–1 from four disks, C18O 2–1 and HCO+ 3–2 from three disks, HCN 3–2, CS 5–4, and DCO+ 3–2 from two disks, and C2H 3–2 and DCN 3–2 from one disk each. H2CO 3–2 is undetected at the sensitivity of our observations. The millimeter continuum images of HD 34282 suggest a faint, unresolved source ∼5.″0 away, which could arise from a distant orbital companion or an extended spiral arm. We fold our sample into a compilation of T Tauri and Herbig AeBe/F disks from the literature. Altogether, most line fluxes generally increase with millimeter continuum flux. Line flux ratios between CO 2–1 isotopologs are nearest to unity for the Herbig AeBe/F disks. This may indicate emitting layers with relatively similar, warmer temperatures and more abundant CO relative to the disk dust mass. Lower HCO+ 3–2 flux ratios may reflect lower ionization in Herbig AeBe/F disks. Lower detection rates and flux ratios for DCO+ 3–2, DCN 3–2, and H2CO 3–2 suggest smaller regimes of cold chemistry around the luminous Herbig AeBe/F stars.

Experimental Study of a PowerCore Filter Bed Operating in a Two-Stage System for Cleaning the Inlet Air of Internal Combustion Engines

Small dust grains cause a higher intensity of increase in the flow resistance of the fibrous filter bed, which, due to the established value of the permissible resistance, results in a shorter period of operation of the air filter and the vehicle. At the same time, the mass of dust per unit of filtration area takes on smaller values. Such a phenomenon occurs in the two-stage “multicyclone-baffle filter” engine inlet air filtration system. The main objective of this study was to experimentally determine the mass of dust retained per unit of filtration area (dust absorption coefficient km) of the PowerCore filter bed operating under two-stage filtration conditions, which cannot be found in the available literature. The original methodology and conditions for determining the dust absorption coefficient km of a PowerCore filter bed operating under two-stage filtration conditions are presented. Tests were carried out on the characteristics of filtration efficiency and accuracy, as well as on the flow resistance of a filtration unit consisting of a single cyclone and a PowerCore test filter with an appropriately selected surface area of filter material. During the tests, conditions corresponding to the actual conditions of vehicle use and air filter operation were maintained, including filtration speed and the dust concentration in the air. The experimentally determined dust absorption coefficient of the PowerCore research filters operating in a two-stage filtration system took on values in the range of km = 199–219 g/m2. The dust absorption coefficient km of the PowerCore research filter operating under single-stage filtration conditions reached a value of km = 434 g/m2, which is twice as high. Prediction of the mileage of a car equipped with a single-stage and two-stage “multi-cyclone-partition” filtration system was carried out, showing the usefulness of the experimentally determined dust absorption coefficients km.

PROTECTION OF THE ATMOSPHERE OF URBANIZED AREAS FROM DUST EMISSIONS DURING THE MANUFACTURE OF AERATED CONCRETE STRUCTURES

The article provides a solution to the urgent task of ensuring the protection of the natural environment and vital human interests from the negative effects of dust emissions generated during the production of aerated concrete and construction products based on it. It has been established that when traditional dust emission cleaning systems with cyclones is used, dust is emitted into the atmospheric air, and up to 100 % of the mass of dust is represented with particles of up to 20 microns in size. At the same time their median diameter is 12 microns, the percentage of particles with sizes less than 10 microns (PM10) is 40 %, the percentage of particles with sizes less than 2,5 microns (PM2,5) is 0.5 %. The percentage of particles in the atmospheric air near the industrial site in the summer varies: for PM10 – from 12 % to 40 %; for PM2,5 – from 0.3 % to 0.5 %. At the border of the sanitary protection zone these values are 80 % and 0.5 %, respectively. In order to reduce dust entering the atmosphere during the production of aerated concrete and construction products based on it, two options for the layout of emission dust removal systems with two consecutively installed dust collectors with counter-rotating flows, two additional devices of smaller sizes, with the organization of suction from the hopper of the main dust collector of the second stage are proposed and from the bunker of one of the additional devices. The use of the proposed dust cleaning system showed that the content of PM10 particles in the stream, emitted into the atmosphere, was decreased by 40 %, the content of PM2,5 particles – by 20 %. At the same time, the emission of dust into the atmosphere was decreased by 8.9 times. Dependencies characterizing the degree of reduction of dust emissions into the atmosphere were established, as well as the ranges of changes in the regime and design parameters of the proposed dust cleaning systems, which ensure the least amount of dust entering the environment and the least energy costs for carrying out dust removal processes during the production of aerated concrete and building structures based on it.

Survey of Orion Disks with ALMA (SODA)

Context. External far-ultraviolet (FUV) irradiation of protoplanetary disks has an important impact on their evolution and ability to form planets. However, nearby (&lt; 300 pc) star-forming regions lack sufficiently massive young stars, while the Trapezium cluster and NGC 2024 have complicated star-formation histories and their O-type stars’ intense radiation fields (&gt; 104 G0) destroy disks too quickly to study this process in detail. Aims. We study disk mass loss driven by intermediate (10 − 1000 G0) FUV radiation fields in L1641 and L1647, where it is driven by more common A0- and B-type stars. Methods. Using the large (N = 873) sample size offered by the Survey of Orion Disks with ALMA (SODA), we searched for trends in the median disk dust mass with FUV field strength across the region as a whole and in two separate regions containing a large number of irradiated disks. Results. For radiation fields between 1 − 100 G0, the median disk mass in the most irradiated disks drops by a factor ∼2 over the lifetime of the region, while the 95th percentile of disk masses drops by a factor 4 over this range. This effect is present in multiple populations of stars, and localized in space, to within 2 pc of ionizing stars. We fitted an empirical irradiation – disk mass relation for the first time: Mdust,median = −1.3−0.13+0.14 log10(FFUV/G0) + 5.2−0.19+0.18. Conclusions. This work demonstrates that even intermediate FUV radiation fields have a significant impact on the evolution of protoplanetary disks.

Eccentric Dust Ring in the IRS 48 Transition Disk

Crescent-shaped structures in transition disks hold the key to studying the putative companions to the central stars. The dust dynamics, especially that of different grain sizes, is important to understanding the role of pressure bumps in planet formation. In this work, we present deep dust continuum observation with high resolution toward the Oph IRS 48 system. For the first time, we are able to significantly trace and detect emission along 95% of the ring crossing the crescent-shaped structure. The ring is highly eccentric with an eccentricity of 0.27. The flux density contrast between the peak of the flux and its counterpart along the ring is ∼270. In addition, we detect a compact emission toward the central star. If the emission is an inner circumstellar disk inside the cavity, it has a radius of at most a couple of astronomical units with a dust mass of 1.5 × 10−8 M ⊙, or 0.005 M ⊕. We also discuss the implications of the potential eccentric orbit on the proper motion of the crescent, the putative secondary companion, and the asymmetry in velocity maps.

Can Saharan dust deposition impact snowpack stability in the French Alps?

Abstract. Saharan dust deposits can turn snow-covered mountains into a spectacular orange landscape. When avalanches release, a formerly buried dust layer can become apparent, possibly marking the failure plane. This appearance may suggest a relation between avalanche release and the previously deposited dust, which found mention among recreationists and avalanche professionals alike. While dust deposition affects the absorption of solar energy altering snowpack temperatures and melt rates, to date, there is no clear scientific evidence that dust deposition can significantly modify snow stability. Here we investigate, using an ensemble snow cover model, the impact of dust deposition on snow properties and mechanical stability by comparing simulations with and without dust deposition for synthetic and observed dust deposition events. The study focuses on two typical avalanche situations: artificial triggering on persistent weak layers and natural release of wet-snow avalanches. We study several situations with and without dust deposition and demonstrate how sensitive the impact of dust deposition is to the deposited dust mass, the slope aspect, the elevation and the meteorological conditions following the dust deposition. The additional energy absorbed by the dust layer speeds up warming and may advance surface wetting to ease the formation of a melt-freeze crust. If the crust is buried, the phenomenon of a strong temperature gradient close to the crust may promote the formation of persistent weak layers inside the snowpack. On the other hand, the melt-freeze crust may also lead to an increase in snowpack stability by redistributing the stress applied to weak layers buried below. Regarding wet-snow instability, we show that dust deposition can advance the onset of wet-snow avalanche activity by up to 1 month in spring, as hypothesized in previous studies. Thus, the impact of Saharan dust deposition on snowpack stability can be either neutral, positive or negative, depending on the topographical, snow and meteorological conditions. Even though not all physical processes are implemented, state-of the art snow cover models are able to mimic the speed-up of crust formation, and snow instability models can point out relevant situations for avalanche forecasting.