Dust Distribution Research Articles

Variability of Airborne Dust Fallout and Associated Trace Metals around Industrial Sites in Esfahan, Iran

AbstractThe seasonal and spatial variability of airborne dust deposits and associated trace metals such as Pb, Co, Ni, Cd, Mn in 15 sites surrounding a heavily industrialized region in south Esfahan (central Iran) are investigated. Total deposit rates (TDR) of dusts and trace metals are analyzed, contamination factor (CF) and pollution load index (PLI) are also calculated. Furthermore, correlation and cluster analysis are performed to identify the source of the pollution. The highest dust‐TDR (15.97 g m−2 per season), the highest concentration of trace metals, CF and PLI are recorded in summer because of the lack of precipitation, high temperature, and drought conditions in this season. Pb and Cd show the highest CF values. In the towns near the two major steel mills in the region (i.e., Esfahan Steel Company and Mobarekeh Steel Complex), the CF values for Pb and Cd are about 13 and 12, respectively (i.e., 13 and 12 times higher than the pre‐industrial values, respectively). The spatial distribution maps of the dust deposit rate, dust‐borne trace metals, and the obtained PLI of the trace metals in the study area reveal that the two major industries in the region are the main sources of dust and trace metal distribution.

Revealing Impact Characteristics of the Cassava Dust Explosion Process: Experimental and Numerical Research

The combustion and explosion characteristics of cassava starch and the dispersive physical motion law of dust were systematically studied using a 20 L (=0.02 m3) spherical explosive test device and the numerical simulation method. The experimental results show that the explosion pressure first increases and then decreases with increasing ignition delay time, dust concentration, and spray pressure in the dust storage tank. The maximum explosion pressure was obtained with a dust concentration of 750 g/m3, while the maximum rate of pressure increase was obtained when the concentration was 250 g/m3. The calculated maximum explosion index was 22.3 MPa∙m∙s−1. The simulation results show that the physical movement law of the dust was as follows: high initial velocity → gradual decrease in diffusion velocity → upward linear movement of dust → outward diffusion motion → continuous disorder motion → free settlement → gradual reduction and disorder state → finally, complete settlement. With a powder diffusion time of 120 ms, the dust distribution in the round sphere was the most uniform, which was consistent with the experimental results. After dust ignition, the temperature first gradually increased and then decreased due to heat dissipation. The maximum pressure in the vessel was 46.7 MPa, and the turbulence was the most intense close to the ignition point.

Importance of different parameterization changes for the updated dust cycle modeling in the Community Atmosphere Model (version 6.1)

Abstract. The Community Atmosphere Model (CAM6.1), the atmospheric component of the Community Earth System Model (CESM; version 2.1), simulates the life cycle (emission, transport, and deposition) of mineral dust and its interactions with physio-chemical components to quantify the impacts of dust on climate and the Earth system. The accuracy of such quantifications relies on how well dust-related processes are represented in the model. Here we update the parameterizations for the dust module, including those on the dust emission scheme, the aerosol dry deposition scheme, the size distribution of transported dust, and the treatment of dust particle shape. Multiple simulations were undertaken to evaluate the model performance against diverse observations, and to understand how each update alters the modeled dust cycle and the simulated dust direct radiative effect. The model–observation comparisons suggest that substantially improved model representations of the dust cycle are achieved primarily through the new more physically-based dust emission scheme. In comparison, the other modifications induced small changes to the modeled dust cycle and model–observation comparisons, except the size distribution of dust in the coarse mode, which can be even more influential than that of replacing the dust emission scheme. We highlight which changes introduced here are important for which regions, shedding light on further dust model developments required for more accurately estimating interactions between dust and climate.

KNOWLEDGE IMPROVEMENT OF SANDSTONE’S CRAFTSMEN IN A OCCUPATIONAL LUNG DISEASE PREVETION AT GAMPING VILLAGE

Health education in sandstone’s craftsmen at Gamping Village is one form of community service in the form of counseling to increasing understanding of the potential hazards and health impacts, especially on the lung function of craftsmen caused by exposure to sandstone dust that was inhaled during the production process. In addition to counseling, free health checks were also carried out, distribution of special respirable dust masks and simulations on how to use masks properly. The activity was carried out on June 17, 2022 at the Gamping Village, Tulungagung. The target of this activity was the sandstone craftsmen of Gamping Village. Before the activity was carried out, the activity preparation process was carried out for approximately 1 month starting from determining the extension theme to submitting permits to related parties. As a form of evaluation, the activity was attended by 32 participants consisting of sandstone craftsmen, village ministers and village officials. All participants participated in the activity with great enthusiasm. Counseling activities could run on time and smoothly.

Protostellar collapse simulations in spherical geometry with dust coagulation and fragmentation

ABSTRACT We model the coagulation and fragmentation of dust grains during the protostellar collapse with our newly developed shark code. It solves the gas-dust hydrodynamics in a spherical geometry and the coagulation/fragmentation equation. It also computes the ionization state of the cloud and the Ohmic, ambipolar, and Hall resistivities. We find that the dust size distribution evolves significantly during the collapse, large grain formation being controlled by the turbulent differential velocity. When turbulence is included, only ambipolar diffusion remains efficient at removing the small grains from the distribution, brownian motion is only efficient as a standalone process. The macroscopic gas-dust drift is negligible for grain growth and only dynamically significant near the first Larson core. At high density, we find that the coagulated distribution is unaffected by the initial choice of dust distribution. Strong magnetic fields are found to enhance the small grains depletion, causing an important increase of the ambipolar diffusion. This hints that the magnetic field strength could be regulated by the small grain population during the protostellar collapse. Fragmentation could be effective for bare silicates, but its modeling relies on the choice of ill-constrained parameters. It is also found to be negligible for icy grains. When fragmentation occurs, it strongly affects the magnetic resistivities profiles. Dust coagulation is a critical process that needs to be fully taken into account during the protostellar collapse. The onset and feedback of fragmentation remains uncertain and its modeling should be further investigated.

Geometric Proca with matter in metric-Palatini gravity

In the present work, we study linear, torsion-free metric-Palatini gravity, extended by the quadratics of the antisymmetric part of the Ricci tensor and extended also by the presence of the affine connection in the matter sector. We show that this extended metric-Palatini gravity reduces dynamically to the general relativity plus a geometrical massive vector field corresponding to non-metricity of the connection. We also show that this geometric Proca field couples to fermions universally. We derive static, spherically symmetric field equations of this Einstein-geometric Proca theory. We study possibility of black hole solutions by taking into account the presence of a dust distribution that couples to the geometric Proca. Our analytical and numerical analyses show that the presence of this dust worsens the possibility of horizon formation. We briefly discuss possible roles of this universally-coupled geometric Proca in the astrophysical and collider processes.

Temporal and spatial pattern of dust storms, their polycyclic aromatic hydrocarbons, and human health risk assessment in the dustiest region of the world.

This study evaluated the concentration and health risks of polycyclic aromatic hydrocarbons (PAHs) in Abadan City under 4 different climatic conditions: normal days, dusty days, dust with northwesterly winds, and dust with southeasterly winds. It also determined the sources of aromatics and discussed the relationship between meteorological parameters and PAH concentrations. The spatiotemporal distribution of dust in the area was determined using the HYSPLIT (hybrid single-particle Lagrangian integrated trajectory) back trajectory model, moderate resolution imaging spectroradiometer (MODIS) images. For this purpose, sampling was performed for 70days using an Omni device. The concentrations of 16 PAHs (USEPA) ranged from 46.22 to 90.96ng/m3. The highest concentration of high molecular weight (HMW) PAHs was 4-6 rings, of which 4 rings were predominant in all samples. PAH sources were identified using diagnostic ratios and principal component analysis (PCA), and it was shown that PAHs mainly originate from a mixture of sources, including vehicular emissions, petrol emissions, and traffic. Wind speed was negatively correlated with dust, except on dusty days. This result indicates a decrease in PAH concentrations when wind speed increases. On the other hand, the dust correlation with PAH was positive on normal days, but a negative correlation was observed on dusty days. This result was due to the lower concentration of PAHs from natural resources (such as dust source areas) vs. human resources (such as traffic and industry). PAH health risk assessment in Abadan City showed that the risk of carcinogenesis was higher on normal days and through skin contact. The probability of incremental lifetime cancer risk (ILCR) in all sampling conditions was potential in terms of carcinogenic risk (10-4-10-6). As a critical risk factor, relevant authorities should prevent, control, and reduce it.

A Radio-selected Population of Dark, Long Gamma-Ray Bursts: Comparison to the Long Gamma-Ray Burst Population and Implications for Host Dust Distributions

We present centimeter-band and millimeter-band afterglow observations of five long-duration γ-ray bursts (GRBs; GRB 130131A, 130420B, 130609A, 131229A, 140713A) with dust-obscured optical afterglow emission, known as “dark” GRBs. We detect the radio afterglow of two of the dark GRBs (GRB 130131A and 140713A), along with a tentative detection of a third (GRB 131229A) with the Karl G. Jansky Very Large Array (VLA). Supplemented by three additional VLA-detected dark GRBs from the literature, we present uniform modeling of their broadband afterglows. We derive high line-of-sight dust extinctions of A V,GRB ≈ 2.2– ≳ 10.6 mag. Additionally, we model the host galaxies of the six bursts in our sample, and derive host galaxy dust extinctions of A V,Host ≈ 0.3–4.7 mag. Across all tested γ-ray (fluence and duration) and afterglow properties (energy scales, geometries, and circumburst densities), we find dark GRBs to be representative of more typical unobscured long GRBs, except in fluence, for which observational biases and inconsistent classification may influence the dark GRB distribution. Additionally, we find that A V,GRB is not related to a uniform distribution of dust throughout the host, nor to the extremely local environment of the burst, indicating that a larger-scale patchy dust distribution is the cause of the high line-of-sight extinction. Since radio observations are invaluable to revealing heavily dust-obscured GRBs, we make predictions for the detection of radio emission from host star formation with the next-generation VLA.

A method of regulating the wind field to reduce safety hazards of gas and dust in fully mechanized heading face based on dynamic data

Accumulation of gas and dust in excavation work is a safety risk that remains to be solved. A substantial amount of gas and dust accumulate in fully mechanized heading face outlets, and the press-in tube jet cannot be adjusted dynamically based on the actual physical conditions. To solve the problem, a dynamic data-driven method for optimising gas and dust distribution by regulating the wind field is proposed. This method is based on the immune genetic algorithm and uses dynamic data as the incremental data with the historical data from the mine regulation rules to obtain the optimal incremental regulation rules (IRRs) for the wind field. The experiment was performed in Ningtiaota coal mine, Yulin city, northern Shaanxi, China. The observed wind velocity and gas concentrations were within the specification range when regulated by IRRs. The dust concentrations at the position of the driver and the average concentrations on the return air side decreased by 64.6 % and 56.5 %, respectively, when the outlet was 5 m from the head-on. When the distance of the outlet from the head-on was 10 m, the dust concentrations at the position of the driver and the average concentrations on the return air side dropped by 42.9 % and 68.6 %, respectively. The results from this study provide measures that would improve safety and efficiency during excavation of fully mechanized heading faces.

Magnetised winds in transition discs

Context. Protoplanetary discs are cold, dense, and weakly ionised environments that witness planetary formation. Among these discs, transition discs (TDs) are characterised by a wide cavity (up to tens of au) in the dust and gas distribution. Despite this lack of material, a considerable fraction of TDs are still strongly accreting onto their central star, possibly indicating that a mechanism is driving fast accretion in TD cavities. Aims. The presence of radially extended ‘dead zones’ in protoplanetary discs has recently revived interest in magnetised disc winds (MDWs), where accretion is driven by a large magnetic field extracting angular momentum from the disc. We propose that TDs could be subject to similar disc winds, and that these could naturally explain the fast-accreting and long-lived cavities inferred in TDs. Methods. We present the results of the first 2.5D global numerical simulations of TDs harbouring MDWs using the PLUTO code. We imposed a cavity in the gas distribution with various density contrasts, and considered a power-law distribution for the large-scale magnetic field strength. We assume the disc is weakly ionised and is therefore subject to ambipolar diffusion, as expected in this range of densities and temperatures. Results. We find that our simulated TDs always reach a steady state with an inner cavity and an outer ‘standard’ disc. These models also maintain an approximately constant accretion rate through the entire structure, reaching 10−7 M⊚ yr−1 for typical surface density values. The MDW launched from the cavity is more magnetised and has a significantly larger lever arm (up to 10) than the MDW launched from the outer disc. The material in the cavity is accreted at sonic velocities, and the cavity itself is rotating at 70% of the Keplerian velocity due to the efficient magnetic braking imposed by the MDW. Overall, our cavity matches the dynamical properties of an inner jet emitting disc (JED) and of magnetically arrested discs (MADs) in black-hole physics. Finally, we observe that the cavity is subject to recurring accretion bursts that may be driven by a magnetic Rayleigh-Taylor instability of the cavity edge. Conclusions. Some strongly accreting TDs could be the result of magnetised wind sculpting protoplanetary discs. Kinematic diagnostics of the disc or the wind (orbital velocity, wind speeds, accretion velocities) could disentangle classic photo-evaporation from MDW models.

OMC-2 FIR 4 under the microscope: Shocks, filaments, and a highly collimated jet at 100 au scales

Context. Star-forming molecular clouds are characterised by the ubiquity of intertwined filaments. The filaments have been observed in both high- and low-mass star-forming regions, and they are thought to split into collections of sonic fibres. The locations where filaments converge are termed hubs, and these are associated with the young stellar clusters. However, the observations of filamentary structures within hubs at distances of 75–300 pc require a high angular resolution <2″ (~ 150–600 au) that limits the number of such studies conducted so far. Aims. The integral shaped filament (ISF) of the Orion A molecular cloud is noted for harbouring several hubs within which no filamentary structures have been observed so far. The goal of our study is to investigate the nature of the filamentary structures within one of these hubs, which is the chemically rich hub OMC-2 FIR 4, and to analyse their emission with high density and shock tracers. Methods. We observed the OMC-2 FIR 4 proto-cluster using Band 6 of the Atacama Large (sub-)Millimetre Array (ALMA) in Cycle 4 with an angular resolution of ~0.26″ (100 au). We analysed the spatial distribution of dust, the shock tracer SiO, and dense gas tracers (i.e., CH3OH, CS, and H13CN). We also studied the gas kinematics using SiO and CH3OH maps. Results. Our observations for the first time reveal interwoven filamentary structures within OMC-2 FIR 4 that are probed by several tracers. Each filamentary structure is characterised by a distinct velocity as seen from the emission peak of CH3OH lines. They also show transonic and supersonic motions. SiO is associated with filaments and also with multiple bow-shock features. The bow-shock features have sizes between ~500 and 2700 au and are likely produced by the outflow from HOPS-370. Their dynamical ages are <800 yr. In addition, for the first time, we reveal a highly collimated SiO jet (~1°) with a projected length of ~5200 au from the embedded protostar VLA 15. Conclusions. Our study unveiled the previously unresolved filamentary structures as well as the shocks within OMC-2 FIR 4. The kinematics of the filamentary structures might be altered by external and/or internal mechanisms such as the wind from H II regions, the precessing jet from the protostellar source HOPS-370, or the jet from VLA 15. While the complexity of the region, coupled with the limited number of molecular lines in our dataset, makes any clear association with these mechanisms challenging, our study shows that multi-scale observations of these regions are crucial for understanding the accretion processes and flow of material that shape star formation.

Assessing Air Pollution and Determining the Composition of Airborne Dust in Urbanized Areas: Granulometric Characteristics

The article focuses on the problem of atmospheric pollution in urban areas caused by particulate matter, which is a problem for most industrial cities. The work aims to assess air pollution by particulate matter PM10 and PM2.5; determine the composition of airborne dust in a zone free of any industrial activity; obtain statistical characteristics of dust distribution in the atmospheric air of urbanized areas according to granulometric characteristics. The issues of PM10 and PM2.5 presence in the atmospheric air of urban and industrial centers in major European cities were analyzed. The degree of air pollution by PM10 and PM2.5 in the autumn-winter season 2020–2021 in Chelyabinsk city was assessed by gravimetry, considering the air quality standards valid in Russia and the European Union. It was found that the average concentration of particulate matter in the air of the urbanized areas of Chelyabinsk in the six months of the autumn-winter period 2020–2021 was 83 µg/m3 and exceeded the MPC (maximum permissible concentration) 2.1 times. The average value of the concentration of fine dust fractions for six months of the study period was 67 µg/m3, exceeding the MPC by 2.7 times. The obtained results indicate that there is a big problem of pollution, therefore it is important to apply the necessary actions to restore the state of air quality standards, which do not cause health risks to the population exposed to ultrafine particulate matter.

Radiation pressure-driven outflows from dusty AGN

ABSTRACT Radiation pressure-driven outflows from luminous accreting supermassive black holes are an important part of active galactic nucleus (AGN) feedback. The effective Eddington limit, based on absorption of radiation by dust, not electron scattering, is revealed in the plane of AGN absorption column density NH as a function of Eddington fraction λEdd = Lbol/LEdd, where a lack of objects is seen in the region where the effective limit is exceeded. Here, we conduct radiation simulation using the cloudy code to deduce the radiative force applied on to dusty gas at the nucleus and compare to the gravitational force to reveal the outflow region and its boundary with long-lived absorption clouds. We also investigate how the outflow condition is affected by various AGN and dust properties and distribution. As expected, the dust abundance has the largest effect on the NH–λEdd diagram since the higher the abundance, the more effective the radiative feedback, while the impact of the inner radius of the dusty gas shell, the shell width, and the AGN spectral shape are relatively negligible. The presence of other central masses, such as a nuclear star cluster, can also make the feedback less effective. The AGN spectral energy distribution depends on the mass of the black hole and its spin. Though the effects of the AGN spectral energy distribution on the diagram are relatively small, the fraction of ionizing ultraviolet photons from the blackbody accretion disc is affected more by black hole mass than spin, and can influence the efficiency of radiation pressure.

Dust extinction map of the Galactic plane based on the VVV survey data

ABSTRACT Dust extinction is one of the most reliable tracers of the gas distribution in the Milky Way. The near-infrared (NIR) Vista Variables in the Vía Láctea (VVV) survey enables extinction mapping based on stellar photometry over a large area in the Galactic plane. We devise a novel extinction mapping approach, XPNICER, by bringing together VVV photometric catalogues, stellar parameter data from StarHorse catalogues, and previously published X percentile and PNICER extinction mapping techniques. We apply the approach to the VVV survey area, resulting in an extinction map that covers the Galactic disc between 295° ≲ l ≲ 350° and −2° ≲ b ≲ 2°, and the Galactic bulge between −10° ≲ b ≲ 5°. The map has 30 arcsec spatial resolution and it traces extinctions typically up to AV ∼ 10–20 mag and maximally up to AV ∼ 30 mag. We compare our map to previous dust-based maps, concluding that it provides a high-fidelity extinction-based map, especially in its ability to recover both the diffuse dust component of the Galaxy and moderately extincted giant molecular cloud regions. The map is especially useful as independent, extinction-based data on the Galactic dust distribution and applicable for a wide range of studies from individual molecular clouds to the studies of the Galactic stellar populations.

Evaluation of WRF-Chem-RTFDDA dust forecasts over the MENA region using in-situ and remote-sensing observations

We employed the combined WRF-Chem-RTFDDA model to forecast dust storms in the Middle East and North Africa (MENA). WRF-Chem simulates the emission, transport, mixing, and chemical transformation of trace gases and aerosols simultaneously with the meteorology. RTFDDA continuously assimilates both conventional and nonconventional meteorological observations and provides improved initial conditions for dust analyses and forecasts. WRF-Chem-RTFDDA was run at a horizontal resolution of 9 km using the dust only option without inclusion of anthropogenic aerosols and chemical reactions. The synoptic conditions of the dust events were characterized by a cold front at the low level and an upper-level low-pressure system over the Western Mediterranean. WRF-Chem-RTFDDA was run in continuous assimilation mode, assimilating meteorological observations only, and launching 48-h free forecasts (FF) every 6 h. Two cold starts (CSs) for data assimilation and dust emissions initiation were performed during the study period. NCEP/GFS global analyses and forecasts provided initial and lateral boundary conditions. No global dust model was used for initialization and no dust observations were assimilated. We analyzed the skill of the WRF-Chem-RTFDDA system in reproducing the horizontal and vertical distributions of dust by comparing the FF to Meteosat SEVIRI dust images, MODIS AOD retrievals, CALIPSO extinction coefficients and CAMS aerosols-reanalysis AOD calculations. The skill was analyzed as a function of FF lead time and of the period of time from the CSs. RMSE, bias and correlation between the modeled and CALIPSO measured extinction coefficients were also examined. WRF-Chem-RTFDDA reproduced the main features of the studied dust storms reasonably well. The time distance from the CSs played a more significant role in determining the dust-forecast skill than free-forecast lead time. Since no external dust information was provided to the model, dust emissions and dust spin-up by WRF-Chem played a critical role in dust forecasts. The vertical extent of the CALIPSO extinction coefficients were reasonably well reproduced once model emissions were spun-up. False alarms rates range from 0.03 to 0.26, with many below 0.15, indicating satisfactory performance as a warning system. This study shows the feasibility of dust forecasts using minimal input data over the MENA region.

Creation field cosmological models for dust distribution and time-dependent cosmological term (Λ) in Bianchi type II space-time

In this paper, we present solution of Einstein field equations which admit dust distribution and negative energy massless scalar field as a source with cosmological term ([Formula: see text]) in the frame work of Bianchi type II space-time. The models satisfy conservation equation and creation field increases with time satisfying the result as investigated by Hoyle and Narlikar [A new theory of gravitation, Proc. Roy. Soc. A 282 (1964) 191]. The deceleration parameter ([Formula: see text]) for the model (22) shows a transition from decelerating to accelerating regime with creation. A comparison with other cosmological models shows a transition from decelerating to accelerating regime with and without creation is mentioned. The present model is free from singularity, particle horizon and provides a natural explanation for inflationary scenario and isotropization. These features make the creation field cosmological models theoretically superior to the Big Bang models. Creation field and Einstein field equation are derived using principle of least action and the Lagrangian formulation of variable cosmological term is derived as mentioned by Moffat [Lagrangian formulation of a solution to the cosmological constant problem (1996), arXiv:astro-ph/9608202v1]. The current creation rate with other physical consequences is also discussed. For illustrative purposes, evolutionary behaviors of some cosmological parameters are shown graphically. In the figures, the cosmic time [Formula: see text] is given in gravitational units assuming the velocity of light [Formula: see text]. This [Formula: see text] and [Formula: see text]. Therefore, by multiplying cosmic time [Formula: see text] by (light years)−1, we obtain the coordinate time in years.

The Effect of Gas and Surface Temperature on Cold-Side and Hot-Side Turbine Deposition

Abstract Deposition studies were conducted using two impingement jet facilities: a 60 m/s cold jet (830–950 K) impinging on a heated Hastelloy-X surface (1033–1255 K) and a 215 m/s hot jet (1450–1625 K) impinging on an uncooled ceramic target or a cooled thermal barrier coated (TBC) surface (1090–1400 K). These can be considered analogs for an internal impingement cooling jet flow and an external nozzle guide vane leading edge flow respectively. Airflows were seeded with 0–10 µm Arizona road dust and deposition accumulated over a period of 5–10 min. Selected tests were completed with other size distributions. Studies were conducted by varying flow temperature at constant surface temperature and vice-versa. For both hot and cold impingement jets, the sensitivity of capture efficiency to fluid (and thus particle) temperature was found to be roughly double the sensitivity to surface temperature. Hot jet tests with three different size distributions of dust (0–5, 0–10, and 5–10 µm) allowed particle size sensitivity to be evaluated. For both target types (ceramic and cooled TBC), the 0–10 µm test dust produced the highest deposition rate of the three size distributions. Possible explanations for the observed behavior are proposed. Companion CFD studies modeling both impinging jets with particle deposition demonstrate that temperature induced variations in particle trajectories alone are not sufficient to explain observed deposition trends with temperature. Implications for the development of a universal sticking model relevant to gas turbine deposition are discussed.

Determining the dust environment of an unknown comet for a spacecraft flyby: The case of ESA’s Comet Interceptor mission

Context.An assessment of the dust environment of a comet is needed for data analysis and planning spacecraft missions, such as ESA’s Comet Interceptor (CI) mission. The distinctive feature of CI is that the target object will be defined shortly before (or even after) launch; as a result, the properties of the nucleus and dust environment are poorly constrained, and therefore make the assessment of the dust environment challenging.Aims.The main goal of the work is to provide realistic estimations of a dust environment based on very general parameters of possible target objects.Methods.Contemporary numerical models of a dusty-gas coma were used to obtain spatial distribution of dust for a given set of parameters. By varying parameters within a range of possible values, we obtained an ensemble of possible dust distributions. Then, this ensemble was statistically evaluated in order to define the most probable cases and hence reduce the dispersion. This ensemble can not only be used to estimate the likely dust abundance along a flyby trajectory of a spacecraft, for example, but also to quantify the associated uncertainty.Results.We present a methodology of the dust environment assessment for the case when the target comet is not known beforehand (or when its parameters are known with large uncertainty). We provide an assessment of dust environment for the CI mission. We find that the lack of knowledge of any particular comet results in very large uncertainties (~3 orders of magnitude) for the dust densities within the coma. The most sensitive parameters affecting the dust densities are the dust size distribution, the dust production rate, and coma brightness, often quantified by Afρ. Further, the conversion of a coma’s brightness (Afρ) to a dust production rate is poorly constrained. The dust production rate can only be estimated down to an uncertainty of ~0.5 orders of magnitude if the dust size distribution is known in addition to the Afρ.Conclusions.To accurately predict the dust environment of a poorly known comet, a statistical approach needs to be taken to properly reflect the uncertainties. This can be done by calculating an ensemble of comae covering all possible combinations within parameter space as shown in this work.

A Three-Dimensional Analytical Model of the Interstellar Extinction within the Nearest Kiloparsec

We present a new version of our analytical model of the spatial interstellar extinction variations within the nearest kiloparsec. This model treats the 3D dust distribution as a superposition of three overlapping layers: (1) the layer along the Galactic midplane, (2) the layer in the Gould Belt, and (3) the layer passing through the Cepheus and Chamaeleon dust cloud complexes. In each layer the dust density decreases exponentially with increasing distance from the midplane of the layer. In addition, there are sinusoidal longitudinal extinction variations along the midplane of each layer. We have found the most probable values of 29 parameters of our model using four data sets: the 3D stellar reddening maps by Gontcharov (2017), Lallement et al. (2019), and Green et al. (2019) and the extinctions inferred by Anders et al. (2022) for 993291 giants from the Gaia EDR3. All of the data give similar estimates of the model parameters. The extinction for a star or a point in space is predicted by our model with an accuracy from $\sigma(A_\mathrm{V})=0.07$ to 0.37 for high and low Galactic latitudes, respectively. The natural fluctuations of the dust medium dominate in these values. When ignoring the fluctuations of the medium, the average extinction for an extended object (a galaxy, a star cluster, a dust cloud) or a small region of space is predicted by our model with an accuracy from $\sigma(A_\mathrm{V})=0.04$ to 0.15 for high and low Galactic latitudes, respectively. Green et al. (2019) and Anders et al. (2022) give in unison an estimate of $A_\mathrm{V}=0.12^m$ for the extinction at high latitudes across the whole Galactic dust half-layer above or below the Sun with the natural fluctuations of the medium $\sigma(A_\mathrm{V})=0.06^m$. Our model is a step to explain how a substantial amount of dust ended up far from the Galactic midplane.

Distribution of fine dust and black carbon indoors and outdoors of an elementary school adjacent to high traffic road

Distribution of fine dust and black carbon indoors and outdoors of an elementary school adjacent to high traffic road