dust formation
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2022 ◽  
Vol 6 (1) ◽  
pp. 12
Author(s):  
Thinh H. Nguyen ◽  
Edward F. Guinan

Abstract VY Canis Majoris (VY CMa) is one of the largest, most luminous red supergiant (RSG) stars in the Galaxy. This huge oxygen-rich RSG may be on the verge of becoming a bright core-collapse Type-II supernova. Over the 20th century, VY CMa has been undergoing episodic large quasi-periodic light variations. It has experienced two “great dimming” episodes during ∼1920–1950 and ∼1985–1995. During these, the star underwent large (1–2.5 mag) quasi-periodic light variations with dominant periods ranging between ∼1415 and 1565 days. In addition to experiencing large quasi-periodic light variations, VY CMa became fainter by 1.0–1.5 mag during the 1920–1950 episode. There is evidence that the star’s brightness decreased from ∼6.5–7.0 to ∼8.0–8.5 mag from 1850 to after 1900. These long-term dimming events may arise from dust formation from previously expelled gas. The light variations and the “dimmings” of VY CMa far surpass the recent “great dimming” of Betelgeuse.


2021 ◽  
Author(s):  
Juri Romazanov ◽  
Andreas Kirschner ◽  
Sebastijan Brezinsek ◽  
Richard A Pitts ◽  
Dmitriy V. Borodin ◽  
...  

Abstract The Monte-Carlo code ERO2.0 was used to simulate steady-state erosion and transport of beryllium (Be) in the ITER main chamber. Various plasma scenarios were tested, including a variation of the main species (hydrogen, deuterium, helium), plasma conditions (density, temperature, flow velocity) and magnetic configurations. The study provides valuable predictions for the Be transport to the divertor, where it is expected to be an important contributor to dust formation and fuel retention due to build-up of co-deposited layers. The Be gross and net erosion rates provided by this study can help identifying first wall regions with potentially critical armour lifetime.


2021 ◽  
Vol 5 (11) ◽  
pp. 273
Author(s):  
Richard J. Rudy ◽  
Ray W. Russell ◽  
Michael L. Sitko

Abstract Infrared spectra of the dusty nova V1112 Persei (Nova Persei 2020) are presented from 29 and 48 days after the onset of dust formation, the later epoch corresponding to when obscuration by the nova dust was at a maximum. The dust emission was featureless and had temperatures of approximately 880 K and 690 K for the two epochs, respectively. Some dust formed along the line of sight and the total extinction for V1112 Per increased from E(B-V) = 0.8 prior to dust formation, to 1.2 on February 3, to 1.4 by February 22. Emission lines of both carbon and oxygen were present along with the dust emission indicating that the dust did not consume all of either of these element.


Author(s):  
A. S. Seminenko ◽  
K. I. Logachev ◽  
A. V. Goltsov ◽  
O. A. Averkova

On the basis of the obtained analytical dependencies, the expediency of fan loading of bunkers with powdery bulk material has been proved. The design of an annular charging device, which reduces dust formation, using the Coanda effect is proposed. The rational design and technological parameters of the developed device are numerically and experimentally determined.


Author(s):  
Thomas P. Mangan ◽  
Kevin M. Douglas ◽  
Rachel E. Lade ◽  
David Gobrecht ◽  
Leen Decin ◽  
...  

Author(s):  
V.I. Golik ◽  
◽  
Z.A. Gashimova ◽  
M.Yu. Liskova ◽  
Ch.B. Kongar-Syuryun ◽  
...  

Technogenic factors that have a negative effect on the environment and humans are analyzed. The integrated effect of negative impact on the environment aggravated by the number of factors is revealed. These factors include the following: gorges, river valleys and mountain landscapes. From the previously conducted studies it was concluded that the main source of negative effects on living organisms is the mineralized dust. The actual task of the study is determined, which consists in detailing the mechanisms and methods of the mineralized dust formation for improving the methods of minimizing its formation. Using the example of an open pit development of a dolomite deposit the relationship is established between the indicators of atmospheric dusting by the products of rock technological crushing and grinding. Dependence is established related to the dust emission intensity on the air flow velocity and dust concentration. It is proved that all the dust-like products formed as the result of mining and processing of the mineral raw materials have dimensions that allow them to move with the help of air masses. The results of the experiments on solving the problem of reducing dust by minimizing the output of mobile dust classes are presented (studies of the granulometric composition of rocks of various types with differentiation by type of the dust source, the mechanism of pollution using trapping screens and the development of directions for minimizing dusting of the atmosphere of the quarry and the surrounding area). The measures to reduce dust formation are proposed. The model for assessing the potential of environmental pollution by gas and dust products is developed. The proposed measures and the developed model will allow to minimize the effect of mining production on the environment of the region and the health of the workers of the mining enterprise and the residents of the region. The results obtained may be in demand when improving existing and developing new methods for improving occupational safety in the mining industry.


2021 ◽  
Vol 922 (1) ◽  
pp. 5
Author(s):  
Ryan M. Lau ◽  
Samaporn Tinyanont ◽  
Matthew J. Hankins ◽  
Michael C. B. Ashley ◽  
Kishalay De ◽  
...  

Abstract We present optical and infrared (IR) light curves of NaSt1, also known as Wolf–Rayet 122, with observations from Palomar Gattini-IR (PGIR), the Zwicky Transient Facility (ZTF), the Katzman Automatic Imaging Telescope, the Asteroid Terrestrial-impact Last Alert System, and the All-Sky Automated Survey for Supernovae (ASAS-SN). We identify a P = 309.7 ± 0.7 day photometric period from the optical and IR light curves that reveal periodic, sinusoidal variability between 2014 July and 2021 July. We also present historical IR light curves taken between 1983 July and 1989 May, which show variability consistent with the period of the present-day light curves. In the past, NaSt1 was brighter in the J band with larger variability amplitudes than the present-day PGIR values, suggesting that NaSt1 exhibits variability on longer (≳decade) timescales. Sinusoidal fits to the recent optical and IR light curves show that the amplitude of NaSt1's variability differs at various wavelengths and also reveal significant phase offsets of 17.0 ± 2.5 day between the ZTF r and PGIR J light curves. We interpret the 310 day photometric period from NaSt1 as the orbital period of an enshrouded massive binary. We suggest that the photometric variability of NaSt1 may arise from variations in the line-of-sight optical depth toward circumstellar optical/IR-emitting regions throughout its orbit due to colliding-wind dust formation. We speculate that past mass transfer in NaSt1 may have been triggered by Roche-lobe overflow (RLOF) during an eruptive phase of an Ofpe/WN9 star. Lastly, we argue that NaSt1 is no longer undergoing RLOF mass transfer.


2021 ◽  
Vol 2057 (1) ◽  
pp. 012035
Author(s):  
AG Matveeva ◽  
TS Skripkina ◽  
UE Bulanova ◽  
VA Bukhtoyarov ◽  
AL Bychkov ◽  
...  

Abstract Energy efficiency – a compromise between reaction depth and expended energy - is an actual question for any technology implementation. Mechanochemical technology for brown coal deep processing has one more compromise - between reaction depth and dust formation. Indeed, the depth of mechanochemical reactions usually correlates with grinding efficiency, but for coal cases dust formation is an unwanted process. Here we consider a solid-state mechanochemical reaction of humic acid oxidation by sodium percarbonate in one laboratory mill at different conditions. The ratio between the grinding bodies load and the payload was varied, the reaction yield and the ground samples characteristics were controlled.


2021 ◽  
Vol 2057 (1) ◽  
pp. 012136
Author(s):  
Yu A Geller ◽  
I S Antanenkova ◽  
M A Aparushkina

Abstract Possible methods of dust formation during the production of polyethylene terephthalate granulate and its preparation for molding are considered. The features and patterns of dust formation during drying in an active hydrodynamic layer at different speeds and temperatures are revealed.


2021 ◽  
Author(s):  
Ting-Wan Chen ◽  
Seán Brennan ◽  
Roger Wesson ◽  
Morgan Fraser ◽  
Tassilo Schweyer ◽  
...  

Abstract We investigate the thermal emission and extinction from dust associated with the nearby superluminous supernova (SLSN) 2018bsz. Our dataset has daily cadence and simultaneous optical and near-infrared coverage up to ~ 100 days, together with late time (+1.7 yr) MIR observations. At 230 days after light curve peak the SN is not detected in the optical, but shows a surprisingly strong near-infrared excess, with r - J > 3 mag and r - Ks > 5 mag. The time evolution of the infrared light curve enables us to investigate if the mid-infrared emission is from newly formed dust inside the SN ejecta, from a pre-existing circumstellar envelope, or interstellar material heated by the radiation from the SN. We find the latter two scenarios can be ruled out, and a scenario where new dust is forming in the SN ejecta at epochs > 200 days can self-consistently reproduce the evolution of the SN flux. We can fit the spectral energy distribution well at +230d with 5x10-4 solar mass of carbon dust, increasing over the following several hundred days to 10-2 solar mass by +535d. SN 2018bsz is the first SLSN showing evidence for dust formation within the SN ejecta, and appears to form ten times more dust than normal core-collapse SNe at similar epochs. Together with their preference for low mass, low metallicity host galaxies, we suggest that SLSNe may be a significant contributor to dust formation in the early Universe.


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