Science.gov

Sample records for dust production mass

  1. Dust Production and Mass Loss in Cool Evolved Stars

    NASA Technical Reports Server (NTRS)

    Boyer, M. L.

    2013-01-01

    Following the red giant branch phase and the subsequent core He-burning phase, the low- to intermediate-mass stars (0.8mass <8) begin to ascend the asymptotic giant branch (AGB). Pulsations levitate material from the stellar surface and provide density enhancements and shocks, which can encourage dust formation and re-processing. The dust composition depends on the atmospheric chemistry (abundance of carbon relative to oxygen), which is altered by dredging up newly formed carbon to the surface of the star. I will briefly review the current status of models that include AGB mass loss and relate them to recent observations of AGB stars from the Surveying the Agents of Galaxy Evolution (SAGE) Spitzer surveys of the Small and Large Magellanic Clouds, including measures of the total dust input to the interstellar medium from AGB stars.

  2. DUST PRODUCTION AND MASS LOSS IN THE GALACTIC GLOBULAR CLUSTER NGC 362

    SciTech Connect

    Boyer, Martha L.; Gordon, Karl D.; Meixner, Margaret; Sewilo, Marta; Shiao, Bernie; Whitney, Barbara; McDonald, Iain; Van Loon, Jacco Th.; Oliveira, Joana M.; Babler, Brian; Bracker, Steve; Meade, Marilyn; Block, Miwa; Engelbracht, Charles; Misselt, Karl; Hora, Joe; Indebetouw, Remy

    2009-11-01

    We investigate dust production and stellar mass loss in the Galactic globular cluster NGC 362. Due to its close proximity to the Small Magellanic Cloud (SMC), NGC 362 was imaged with the Infrared Array Camera and Multiband Imaging Photometer cameras onboard the Spitzer Space Telescope as part of the Surveying the Agents of Galaxy Evolution (SAGE-SMC) Spitzer Legacy program. We detect several cluster members near the tip of the red giant branch (RGB) that exhibit infrared excesses indicative of circumstellar dust and find that dust is not present in measurable quantities in stars below the tip of the RGB. We modeled the spectral energy distribution (SED) of the stars with the strongest IR excess and find a total cluster dust mass-loss rate of 3.0{sup +2.0}{sub -1.2} x 10{sup -9} M{sub sun} yr{sup -1}, corresponding to a gas mass-loss rate of 8.6{sup +5.6}{sub -3.4} x 10{sup -6} M{sub sun} yr{sup -1}, assuming [Fe/H] =-1.16. This mass loss is in addition to any dustless mass loss that is certainly occurring within the cluster. The two most extreme stars, variables V2 and V16, contribute up to 45% of the total cluster dust-traced mass loss. The SEDs of the more moderate stars indicate the presence of silicate dust, as expected for low-mass, low-metallicity stars. Surprisingly, the SED shapes of the stars with the strongest mass-loss rates appear to require the presence of amorphous carbon dust, possibly in combination with silicate dust, despite their oxygen-rich nature. These results corroborate our previous findings in omega Centauri.

  3. Mass production of multi-wall carbon nanotubes by metal dusting process with high yield

    SciTech Connect

    Ghorbani, H.; Rashidi, A.M.; Rastegari, S.; Mirdamadi, S.; Alaei, M.

    2011-05-15

    Research highlights: {yields} Synthesis of carbon nanotubes over Fe-Ni nanoparticles supported alloy 304L. {yields} Production of carbon nanotubes with high yield (700-1000%) and low cost catalyst. {yields} Optimum growth condition is CO/H{sub 2} = 1/1, 100 cm{sup 3}/min, at 620 {sup o}C under long term repetitive thermal cycling. {yields} Possibility of the mass production by metal dusting process with low cost. -- Abstract: Carbon nanotube materials were synthesized over Fe-Ni nanoparticles generated during disintegration of the surface of alloy 304L under metal dusting environment. The metal dusting condition was simulated and optimized through exposing stainless steel samples during long term repetitive thermal cycling in CO/H{sub 2} = 1/1, total gas flow rate 100 cm{sup 3}/min, at 620 {sup o}C for 300 h. After reaction, surface morphology of the samples and also carbonaceous deposition which had grown on sample surfaces were examined by stereoscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results revealed that multi-wall carbon nanotubes could be formed over nanocatalyst generated on the alloy surface by exploiting metal dusting process. By optimization of reaction parameters the yields of carbon nanotube materials obtained were 700-1000%. Also it has been shown herein that the amount of carbon nanotube materials remarkably increases when the reaction time is extended up to 300 h, indicating a possibility of the mass production by this easy method.

  4. DUST PRODUCTION AND MASS LOSS IN THE GALACTIC GLOBULAR CLUSTER 47 TUCANAE

    SciTech Connect

    McDonald, I.; Zijlstra, A. A.; Boyer, M. L.; Van Loon, J. Th.

    2011-04-01

    Dust production among post-main-sequence stars is investigated in the Galactic globular cluster 47 Tucanae (NGC 104) based on infrared photometry and spectroscopy. We identify metallic iron grains as the probable dominant opacity source in these winds. Typical evolutionary timescales of asymptotic giant branch stars suggest the mass-loss rates we report are too high. We suggest that this is because the iron grains are small or elongated and/or that iron condenses more efficiently than at solar metallicity. Comparison to other works suggests metallic iron is observed to be more prevalent toward lower metallicities. The reasons for this are explored, but remain unclear. Meanwhile, the luminosity at which dusty mass loss begins is largely invariant with metallicity, but its presence correlates strongly with long-period variability. This suggests that the winds of low-mass stars have a significant driver that is not radiation pressure, but may be acoustic driving by pulsations.

  5. Variable Stars and The Asymptotic Giant Branch: Stellar Pulsations, Dust Production, and Mass Loss

    NASA Astrophysics Data System (ADS)

    Speck, A. K.

    2014-09-01

    Low- and intermediate-mass stars (1-8 M⊙; LIMS) are very important contributors of material to the interstellar medium (ISM), and yet the mechanisms by which this matter is expelled remain a mystery. In this paper we discuss how interferometry plays a role in studying the interplay between pulsation, mass loss, dust formation, and evolution of these LIMS.

  6. Variable Stars and the Asymptotic Giant Branch: Stellar Pulsations, Dust Production, and Mass Loss

    NASA Astrophysics Data System (ADS)

    Speck, A. K.

    2012-06-01

    Low- and intermediate-mass stars (1-8 M⊙; LIMS) are very important contributors of material to the interstellar medium (ISM), and yet the mechanisms by which this matter is expelled remain a mystery. In this paper we discuss how interferometry plays a role in studying the interplay between pulsation, mass loss, dust formation and evolution of these LIMS.

  7. Stellar Dust Production in Chemically Primitive Environments: Infrared Lightcurves and Mass Loss in Extremely Metal-poor AGB Stars

    NASA Astrophysics Data System (ADS)

    Sonneborn, George

    In their final stage of evolution, asymptotic giant branch (AGB) stars inject a substantial amount of dust into the surrounding interstellar medium, potentially dominating the total stellar dust budgets of their host galaxies. However, stellar models conflict over whether metal-poor AGB stars can condense enough dust to drive a strong stellar wind, so it is unclear what role AGB stars play in the early Universe compared to other dust sources, e.g., in high-redshift quasars that show evidence for massive dust reservoirs. Empirically, AGB stars that are massive enough to contribute in the early Universe are only well studied in the Milky Way and the nearby Magellanic Clouds; all three environments are relatively metal-rich and thus unlikely to be representative of high-redshift AGB stars. This lack of observations of metal-poor AGB stars motivated the survey of DUST in Nearby Galaxies with Spitzer (DUSTiNGS), which imaged 50 nearby dwarf galaxies in the infrared and identified 526 dusty "extreme" AGB stars. The DUSTiNGS stars confirm that dust can form at metallicities as low as 0.008 solar, more than an order of magnitude lower than had been previously observed. However, very little is known about the DUSTiNGS stars; among the unknowns are the photospheric chemistries, stellar masses, temperatures, luminosities, pulsation periods and amplitudes, dust-production rates, and even their statuses as bona fide AGB stars. To eliminate these unknowns, we were awarded 56 hours of Priority 1 observing time in Spitzer's cycle 11 to obtain 6 new epochs of imaging for a subset of the DUSTiNGS variables over an 18 month baseline. These will be the first infrared light curves of metal-poor, dust-producing AGB stars, allowing us to study the influence of metallicity on pulsation and dust production. Combined with additional archival data, our cycle-11 Spitzer program will allow estimates of all of the parameters listed above, enabling the first direct comparisons to models of AGB

  8. FUNDAMENTAL PARAMETERS, INTEGRATED RED GIANT BRANCH MASS LOSS, AND DUST PRODUCTION IN THE GALACTIC GLOBULAR CLUSTER 47 TUCANAE

    SciTech Connect

    McDonald, I.; Zijlstra, A. A.; Boyer, M. L.; Gordon, K.; Meixner, M.; Sewilo, M.; Shiao, B.; Whitney, B.; Van Loon, J. Th.; Hora, J. L.; Robitaille, T.; Babler, B.; Meade, M.; Block, M.; Misselt, K.

    2011-04-01

    Fundamental parameters and time evolution of mass loss are investigated for post-main-sequence stars in the Galactic globular cluster 47 Tucanae (NGC 104). This is accomplished by fitting spectral energy distributions (SEDs) to existing optical and infrared photometry and spectroscopy, to produce a true Hertzsprung-Russell diagram. We confirm the cluster's distance as d = 4611{sup +213}{sub -200} pc and age as 12 {+-} 1 Gyr. Horizontal branch models appear to confirm that no more red giant branch mass loss occurs in 47 Tuc than in the more metal-poor {omega} Centauri, though difficulties arise due to inconsistencies between the models. Using our SEDs, we identify those stars that exhibit infrared excess, finding excess only among the brightest giants: dusty mass loss begins at a luminosity of {approx}1000 L{sub sun}, becoming ubiquitous above L = 2000 L{sub sun}. Recent claims of dust production around lower-luminosity giants cannot be reproduced, despite using the same archival Spitzer imagery.

  9. A mass spectrometry-based method to measure dialkylphosphate degradation products of organophosphorous insecticides in dust and orange juice.

    PubMed

    Weerasekera, Gayanga; Smith, Kimberly D; Quirós-Alcalá, Lesliam; Fernandez, Carolina; Bradman, Asa; Eskenazi, Brenda; Needham, Larry L; Barr, Dana B

    2009-07-01

    Dialkylphosphates (DAPs) are urinary metabolites and breakdown products of organophosphorous (OP) pesticides. Urinary DAPs are widely used to assess exposure to OP pesticides in epidemiologic studies. Recent evidence suggests that preformed DAPs are present in food and that they may also be present in other parts of the environment. Thus, DAP concentrations observed in urine may reflect a person's exposure to both parent OP pesticides and preformed DAPs in food and other environmental media. The presence of preformed DAPs in multiple media may indicate that previous studies have overestimated exposure to OP pesticides and that the use of urinary DAPs as biomarkers of exposure for OP pesticides may not accurately characterize exposure in non-acute settings. To establish the presence of DAPs in environmental and food media, we developed analytical methods to measure six DAPs in dust and orange juice. The limits of detection (LOD) for the dimethyl phosphates (dimethylphosphate (DMP), dimethylthiophosphate, and dimethyldithiophosphate) ranged from 2.8-9.9 ng g(-1) and 0.2-0.4 ng mL(-1) in dust and juice, respectively. The LODs for the diethyl phosphates (diethylphosphate (DEP), diethylthiophosphate, diethyldithiophosphate) ranged from 5.2-10.4 ng g(-1) and 0.5-3.0 ng mL(-1) in dust and juice, respectively. The extraction efficiencies for the analytes ranged from 23% to 91% and from 41% to 85% in dust and orange juice, respectively. DMP was detected in about half of the dust samples whereas DEP was detected in 80% of the dust samples tested. Other DAPs were less frequently detected in dust. Less than 3% of intact pesticide present in the matrices was converted to their respective DAPs during the pre-analytic and analytic process. Evaluation of the conversion of intact pesticides in the samples to DAPs will help us to better understand the contribution of preformed DAPs to urinary DAP concentrations. PMID:20449223

  10. Mass Loss in Massive Stars Across the H-R Diagram: Transients, Dust Production, and the End Stages of Stellar Evolution

    NASA Astrophysics Data System (ADS)

    Levesque, Emily

    2015-08-01

    Mass loss is a critical ingredient in the evolution of massive stars. Effects on massive stellar evolution from parameters such as metallicity and rotation are often the consequence of these parameters’ direct impact on mass loss mechanisms. For moderately massive (10-25Mo) stars, mass loss processes are vital to their late-time evolution as red supergiants and Wolf-Rayet stars as well as the nature and classification of their core-collapse deaths. For more massive stars, extreme or eruptive mass loss episodes can be observed as transient phenomena in their own right and are a defining characteristic of luminous blue variables (LBVs). Mass loss is also vital to our understanding of dust production by massive stars, which can dominate the dust content of the ISM in young galaxies and give rise to objects such as OH/IR stars. In this talk I will discuss recent observational and theoretical work on mass loss in massive stars, including its critical role in transient astronomy, dust production, and stellar evolution.

  11. Modeling of asteroidal dust production rates

    NASA Technical Reports Server (NTRS)

    Durda, Daniel D.; Dermott, Stanley F.; Gustafson, Bo A. S.

    1992-01-01

    The production rate of dust associated with the prominent Hirayama asteroid families and the background asteroidal population are modeled with the intent of using the families as a calibrator of mainbelt dust production. However, the dust production rates of asteroid families may be highly stochastic; there is probably more than an order of magnitude variation in the total area of dust associated with a family. Over 4.5 x 10(exp 9) years of collisional evolution, the volume (mass) of a family is ground down by an order of magnitude, suggesting a similar loss from the entire mainbelt population. Our collisional models show that the number of meteoroids deliverable to Earth also varies stochastically, but only by a factor of 2 to 3.

  12. SHAPING THE DUST MASS-STAR-FORMATION RATE RELATION

    SciTech Connect

    Hjorth, Jens; Gall, Christa; Michałowski, Michał J. E-mail: cgall@phys.au.dk

    2014-02-20

    There is a remarkably tight relation between the observationally inferred dust masses and star-formation rates (SFRs) of Sloan Digital Sky Survey galaxies, M {sub dust} ∝ SFR{sup 1.11}. Here we extend the M {sub dust}-SFR relation to the high end and show that it bends over at very large SFRs (i.e., dust masses are lower than predicted for a given SFR). We identify several distinct evolutionary processes in the diagram: (1) a star-bursting phase in which dust builds up rapidly at early times. The maximum attainable dust mass in this process is the cause of the bend-over of the relation. A high dust-formation efficiency, a bottom-light initial mass function, and negligible supernova shock dust destruction are required to produce sufficiently high dust masses. (2) A quiescent star-forming phase in which the subsequent parallel decline in dust mass and SFR gives rise to the M {sub dust}-SFR relation, through astration and dust destruction. The dust-to-gas ratio is approximately constant along the relation. We show that the power-law slope of the M {sub dust}-SFR relation is inversely proportional to the global Schmidt-Kennicutt law exponent (i.e., ∼0.9) in simple chemical evolution models. (3) A quenching phase which causes star formation to drop while the dust mass stays roughly constant or drops proportionally. Combined with merging, these processes, as well as the range in total baryonic mass, give rise to a complex population of the diagram which adds significant scatter to the original M {sub dust}-SFR relation. (4) At very high redshifts, a population of galaxies located significantly below the local relation is predicted.

  13. Dust Production in Local Group Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Zijlstra, Albert; Sloan, Greg; Bernard-Salas, Jeronimo; Blommaert, Joris A. D. L.; Cioni, Maria-Rosa; Devost, Daniel; Feast, Michael W.; Groenewegen, Martin A. T.; Habing, Harm; Hony, Sacha; Lagadec, Eric; Loup, Cecile; Matsuura, Mikako; Menzies, John W.; Sloan, Greg C.; Waters, L. B. F. M.; Whitelock, Patricia A.; Wood, Peter R.; van Loon, Jacco Th.

    2006-05-01

    The superwind phase on the Asymptotic Giant Branch is a crucial ingredient of stellar and galactic evolution. The superwind ejecta are responsible for much of the interstellar hydrogen of evolved galaxies, and are a dominant contributor to the dust input into the ISM. The superwind determines the final mass of stellar remnants, and therefore affects, e.g., the type-I supernova rate. The characteristics of the superwind are still very poorly known, especially at non-solar metallicities. Spitzer has contributed a large and invaluable dataset on Magellanic Cloud stars, measuring dust, molecular bands and allowing accurate mass-loss measurements. We now propose to extend the (age, metallicity) parameter range by observing a number of other Milky Way satellites. The carbon stars in these galaxies trace an older population than the Magellanic Clouds, and extend to much lower metallicities. They are therefore crucial to allow us to extrapolate the Magellanic Cloud measurements to metal-poor environments. We propose to acquire low-resolution spectra of stars in the Sagittarius dwarf galaxy, Carina, Sculptor and Fornax. The selected stars range in metallicity from -0.55 to -2.0, and in age from 5-8 Gyr. Two low-metallicity planetary nebulae in these galaxies are also included. We will study the dust continuum, dust minerals (SiC, MgS) and gas-phase molecular bands (especially acetylene). Mass loss rates will be determined using our dust models, and we will measure the fractional abundances of amorphous carbon dust and SiC grains. Only Spitzer can provide these crucial measurements of extra-galactic AGB stars. The result will be our first knowledge of mass loss efficiency, dust formation, and dust abundances, at low to very low metallicities. These data are necessary to obtain reliable models of mass loss and of stellar evolution.

  14. Pebble Bed Reactor Dust Production Model

    SciTech Connect

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  15. ALMA Observations of Anisotropic Dust Mass Loss around VY CMa

    NASA Astrophysics Data System (ADS)

    O'Gorman, E.; Vlemmings, W.; Richards, A. M. S.; Baudry, A.; De Beck, E.; Decin, L.; Harper, G. M.; Humphreys, E. M.; Kervella, P.; Khouri, T.; Muller, S.

    2015-12-01

    We present high resolution ALMA Science Verification data of the continuum emission around the highly evolved oxygen-rich red supergiant VY CMa. These data enable us to study the dust in its inner circumstellar environment at a spatial resolution of 129 mas at 321 GHz and 59 mas at 658 GHz, thus allowing us to trace dust on spatial scales down to 11 R⋆ (71 AU). Two prominent dust components are detected and resolved. We find that at least 17% of the dust mass around VY CMa is located in clumps ejected within a more quiescent roughly spherical stellar wind, with a quiescent dust mass loss rate of 5×10-6 M⊙ yr-1. The anisotropic morphology of the dust indicates a continuous, directed mass loss over a few decades, suggesting that this mass loss cannot be driven by large convection cells alone.

  16. Sampling and analysis method for measuring airborne coal dust mass in mixtures with limestone (rock) dust.

    PubMed

    Barone, T L; Patts, J R; Janisko, S J; Colinet, J F; Patts, L D; Beck, T W; Mischler, S E

    2016-01-01

    Airborne coal dust mass measurements in underground bituminous coal mines can be challenged by the presence of airborne limestone dust, which is an incombustible dust applied to prevent the propagation of dust explosions. To accurately measure the coal portion of this mixed airborne dust, the National Institute for Occupational Safety and Health (NIOSH) developed a sampling and analysis protocol that used a stainless steel cassette adapted with an isokinetic inlet and the low temperature ashing (LTA) analytical method. The Mine Safety and Health Administration (MSHA) routinely utilizes this LTA method to quantify the incombustible content of bulk dust samples collected from the roof, floor, and ribs of mining entries. The use of the stainless steel cassette with isokinetic inlet allowed NIOSH to adopt the LTA method for the analysis of airborne dust samples. Mixtures of known coal and limestone dust masses were prepared in the laboratory, loaded into the stainless steel cassettes, and analyzed to assess the accuracy of this method. Coal dust mass measurements differed from predicted values by an average of 0.5%, 0.2%, and 0.1% for samples containing 20%, 91%, and 95% limestone dust, respectively. The ability of this method to accurately quantify the laboratory samples confirmed the validity of this method and allowed NIOSH to successfully measure the coal fraction of airborne dust samples collected in an underground coal mine. PMID:26618374

  17. Vertical Resolved Dust Mass Concentration and Backscatter Coefficient Retrieval of Asian Dust Plume Using Quartz Raman Channel in Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Noh, Young M.; Mueller, Detlef; Shin, Sungkyun

    2016-06-01

    In this work, we present a method for estimating vertical resolved mass concentration of dust immersed in Asian dust plume using Raman scattering of quartz (silicon dioxide, silica). During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profiles of the quartz backscatter coefficient. Since the Raman backscatter coefficient was connected with the Raman backscatter differential cross section and the number density of quartz molecules, the mass concentration of quartz in the atmosphere can be estimated from the quartz backscatter coefficient. The weight percentage from 40 to 70 % for quartz in the Asian dust was estimated from references. The vertical resolved mass concentration of dust was estimated by quartz mass concentration and weight percentage. We also present a retrieval method to obtain dust backscatter coefficient from the mixed Asian dust and pollutant layer. OPAC (Optical Properties of Aerosol and Clouds) simulations were conducted to calculate dust backscatter coefficient. The retrieved dust mass concentration was used as an input parameter for the OPAC calculations. These approaches in the study will be useful for characterizing the quartz dominated in the atmospheric aerosols and estimating vertical resolved mass concentration of dust. It will be especially applicable for optically distinguishing the dust and non-dust aerosols in studies on the mixing state of Asian dust plume. Additionally, the presented method combined with satellite observations is enable qualitative and quantitative monitoring for Asian dust.

  18. Chromospheric dust formation, stellar masers and mass loss

    NASA Technical Reports Server (NTRS)

    Stencel, R. E.

    1986-01-01

    A multistep scenario which describes a plausible mass loss mechanism associated with red giant and related stars is outlined. The process involves triggering a condensation instability in an extended chromosphere, leading to the formation of cool, dense clouds which are conducive to the formation of molecules and dust grains. Once formed, the dust can be driven away from the star by radiation pressure. Consistency with various observed phenomena is discussed.

  19. H2, CO and Dust Emission Around Low Mass Stars

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    We model the thermal balance, the chemistry, and the radiative transfer in dusty disks orbiting young, low mass stars. These models are motivated by observations of infrared and ultraviolet transitions of H2 from protoplanetary disks, as well as millimeter and submillimeter observations of other molecules such as CO, and infrared continuum observations of the dust. The dust grains are heated primarily by the stellar radiation and the infrared radiation field produced by the dust itself. The gas is heated by collisions with warmer dust grains, X-rays from the region close to the stellar surface, UV (ultraviolet) pumping of hydrogen molecules, and the grain photoelectric heating mechanism initiated by UV photons from the central star. We treat cases where the gas to dust ratio is high, because the dust has settled to the midplane and coagulated into relatively large objects. We discuss situations in which the infrared emission from H2 can be detected, and how the comparison of the observations with our models can deduce physical parameters such as the mass and the density and temperature distribution of the gas.

  20. H2, CO and Dust Emission Around Low Mass Stars

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    We model the thermal balance, the chemistry, and the radiative transfer in dusty disks orbiting young, low mass stars. These models are motivated by observations of infrared and ultraviolet transitions of H2 from protoplanetary disks, as well as millimeter and submillimeter observations of other molecules such as CO, and infrared continuum observations of the dust. The dust grains are heated primarily by the stellar radiation and the infrared radiation field produced by the dust itself. The gas is heated by collisions with warmer dust grains, X-rays from the region close to the stellar surface, UV pumping of hydrogen molecules, and the grain photoelectric heating mechanism initiated by UV photons from the central star. We treat cases where the gas to dust ratio is high, because the dust has settled to the midplane and coagulated into relatively large objects. We discuss situations in which the infrared emission from H2 can be detected, and how the comparison of the observations with our models can deduce physical parameters such as the mass and the density and temperature distribution of the gas.

  1. Aerogel dust collection for in situ mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Jones, S. M.; Anderson, M. S.; Davies, A. G.; Kirby, J. P.; Burchell, M. J.; Cole, M. J.

    2015-02-01

    The current technique for conducting in situ mass spectroscopic analysis of dust around extraterrestrial bodies is to have the dust impact a solid plate and analyze the atoms and molecular fragments resulting from the high speed impact. Due to the fact that the kinetic energy from the impact is converted primarily to thermal energy, much of the organic compounds present in the dust may be significantly altered or destroyed. To avoid this problem, aerogel could be used to capture the dust grains, largely intact, maintaining the integrity of the organic compounds in the interior of the dust grains. To demonstrate that organic molecules, present as minor components of silica particles, would survive hypervelocity capture in aerogel and can then be analyzed with mass spectrometry, several light gas gun impact tests and analyses were conducted. Fine particles containing polycyclic aromatic hydrocarbons (PAHs) were captured in aerogel at 5.5 km s-1. The flow of metastable helium from a Direct Analysis Real Time (DART) source was used to desorb and ionize the organics, which were then analyzed with a mass spectrometer. The PAHs were detected and identified by the DART-MS, demonstrating that this method could be used on future flight instruments.

  2. Solar wind mass-loading due to dust

    NASA Astrophysics Data System (ADS)

    Rasca, A. P.; Horányi, M.

    2013-06-01

    Collisionless mass-loading by interplanetary dust particles is expected to cause a significant disruption in the flow of the solar wind. Dust particles near the Sun can become a source of ions and neutrals due to evaporation and sputtering. This mass-loading effect can lead to the formation of collisionless shocks, as it was first discussed in the case of solar wind interaction with comets. This effect can also be compared with a de Laval nozzle, which behaves differently between subsonic and supersonic flows. We investigate the effects of mass-loading resulting from sun-grazing comets or collisions by larger bodies in the vicinity of the Sun, where the solar wind transitions from subsonic to supersonic speeds. We look at results obtained using a simple 1D hydrodynamic model to mass-load ionized dust into the the wind near the sonic point, which are relevant for understanding the acceleration of the solar wind and possible changes in its composition due to dust.

  3. Solar Wind Mass-Loading Due to Dust

    NASA Astrophysics Data System (ADS)

    Rasca, A.; Horanyi, M.

    2011-12-01

    Collisionless mass-loading by interplanetary dust particles is expected to cause a significant disruption in the flow of the solar wind. Dust particles near the Sun can become a source of ions and neutrals due to evaporation and sputtering. This mass-loading effect can lead to the formation of collisionless shocks, as it was first discussed in the case of solar wind interaction with comets. This effect can also be compared with a de Laval nozzle, which behaves differently between subsonic and supersonic flows. We investigate the effects of mass-loading resulting from sun-grazing comets or collisions in the vicinity of the Sun, where the solar wind transitions from subsonic to supersonic speeds. We implement a hydrodynamic numerical model to generate a steady wind extending out to the inner heliosphere. Dust is introduced through a set of mass-loading source terms, and the model is evolved using a shock-capturing scheme. These results are relevant for understanding the acceleration of the solar wind and possible changes in its composition due to dust.

  4. SILICATE DUST SIZE DISTRIBUTION FROM HYPERVELOCITY COLLISIONS: IMPLICATIONS FOR DUST PRODUCTION IN DEBRIS DISKS

    SciTech Connect

    Takasawa, S.; Nakamura, A. M.; Arakawa, M.; Seto, Y.; Sangen, K.; Setoh, M.; Machii, N.; Kadono, T.; Shigemori, K.; Hironaka, Y.; Fujioka, S.; Sano, T.; Watari, T.; Dohi, K.; Ohno, S.; Maeda, M.; Sakaiya, T.; Otani, K.; Takeuchi, T.

    2011-06-01

    Fragments generated by high-velocity collisions between solid planetary bodies are one of the main sources of new interplanetary dust particles. However, only limited ranges of collision velocity, ejecta size, and target materials have been studied in previous laboratory experiments, and the collision condition that enables the production of dust-sized particles remains unclear. We conducted hypervelocity impact experiments on silicate rocks at relative velocities of 9 to 61 km s{sup -1}, which is beyond the upper limit of previous laboratory studies. Sub-millimeter-diameter aluminum and gold spheres were accelerated by laser ablation and were shot into dunite and basalt targets. We analyzed the surfaces of aerogel blocks deployed near the targets using an electron probe micro analyzer and counted the number of particles that contained the target material. The size distributions of ejecta ranged from five to tens of microns in diameter. The total cross-sectional area of dust-sized ejecta monotonically increased with the projectile kinetic energy, independent of impact velocity, projectile diameter, and projectile and target material compositions. The slopes of the cumulative ejecta-size distributions ranged from -2 to -5. Most of the slopes were steeper than the -2.5 or -2.7 that is expected for a collisional equilibrium distribution in a collision cascade with mass-independent or mass-dependent catastrophic disruption thresholds, respectively. This suggests that the steep dust size-distribution proposed for the debris disk around HD172555 (an A5V star) could be due to a hypervelocity collision.

  5. Probing Ancient Mass Loss with AKARI's Extended Dust Emission Objects

    NASA Astrophysics Data System (ADS)

    Tomasino, R.; Ueta, T.; Yamamura, I.; Izumiura, H.

    2014-04-01

    We present the results from the calibration and analysis of 166 far-IR extended thermal dust emission objects that were observed with AKARI’s FIS detector. The primary goal is to map the circumstellar shells of evolved stars in detail to excavate the ancient history of dusty mass loss. After establishing an extended aperture photometry method, we characterized the flux dependent slow transient response correction factors for each of the four wavelength bands. Using the new correction factors for extended (far-IR) emission, we present the photometric values that were calculated for the entire data set and also report our work on morphology characterization of the extended dust shells.

  6. Dust production 680-850 million years after the Big Bang

    NASA Astrophysics Data System (ADS)

    Michałowski, Michał J.

    2015-05-01

    Dust plays an important role in our understanding of the Universe, but it is not obvious yet how the dust in the distant universe was formed. I derived the dust yields per asymptotic giant branch (AGB) star and per supernova (SN) required to explain dust masses of galaxies at z = 6.3-7.5 (680-850 million years after the Big Bang) for which dust emission has been detected (HFLS3 at z = 6.34, ULAS J1120+0641 at z = 7.085, and A1689-zD1 at z = 7.5), or unsuccessfully searched for. I found very high required yields, implying that AGB stars could not contribute substantially to dust production at these redshifts, and that SNe could explain these dust masses, but only if they do not destroy most of the dust they form (which is unlikely given the upper limits on the SN dust yields derived for galaxies where dust is not detected). This suggests that the grain growth in the interstellar medium is likely required at these early epochs.

  7. Dust discs around low-mass main-sequence stars

    NASA Technical Reports Server (NTRS)

    Wolstencroft, R. D.; Walker, Helen J.

    1988-01-01

    The current understanding of the formation of circumstellar disks as a natural accompaniment to the process of low-mass star formation is examined. Models of the thermal emission from the dust disks around the prototype stars Alpha Lyr, Alpha PsA, Beta Pic, and Epsilon Eri are discussed, which indicate that the central regions of three of these disks are almost devoid of dust within radii ranging between 17 and 26 AU, with the temperature of the hottest zone lying between about 115 and 210 K. One possible explanation of the dust-free zones is the presence of a planet at the inner boundary of each cloud which sweeps up grains crossing its orbit.

  8. Mass spectra of organic and inorganic dust particles measured by an impact ionization mass analyzer instrument

    NASA Astrophysics Data System (ADS)

    Salter, J. G.; Sternovsky, Z.; Srama, R.; Postberg, F.; Kempf, S.; Armes, S. P.; Gruen, E.; Horanyi, M.; Drake, K.; Westphal, A.

    2009-12-01

    The composition of individual cosmic dust particles can be measured in-situ using existing techniques and instrumentations. The dust particle impacting on a solid surface with hypervelocity (> 1 km/s) is vaporized and partially ionized. The generated ions are extracted and analyzed using time-of-flight methods. Laboratory calibration measurements are possible at the dust accelerator facility in Heidelberg, Germany. The accelerator is limited to using conductive dust that was limited in the past to Fe, Al or graphite samples. In the recent years, however, dust samples of organic materials and inorganic minerals of cosmic interest were developed that are suitable for application in the accelerator. This is achieved by coating micron and submicron sized dust particles by conductive polymers. Here we present the comparison of spectra measured using organic and inorganic dust samples (polystyrene, poly-[bis(4-vinylthiophenyl)sulphide], Phyrotite). The particles were accelerated to speeds between 3 and 35 km/s. Depending on the projectile type and the impact speed, both aliphatic and aromatic molecular ions and cluster species were identified in the mass spectra with masses up to 400 Daltons. Clusters resulting from the target material (silver) and mixed clusters of target and projectile species were also observed. These fundamental studies are expected to enhance our understanding of cometary, interplanetary and interstellar dust grains, which travel at similar hyper-velocities and are known to contain both aliphatic and aromatic organic compounds.

  9. Satellite measurement of mass of Sahara dust in the atmosphere

    NASA Technical Reports Server (NTRS)

    Fraser, R. S.

    1976-01-01

    Landsat 1 measurements of nadir radiance are used to obtain the mass of particulates in a vertical column of dust from the Sahara Desert. A radiative transfer model, constructed with knowledge of a few values of optical parameters measured from a ship, is developed to account for the measured radiance values. Measurement and model accuracies are discussed. It is found that the mass of particulates with smaller than a 10 micron radius in a vertical column is 1.6 g/sq m.

  10. Steelworks dust -- From waste to product

    SciTech Connect

    Strohmeier, G.; Bonestell, J.E.

    1995-07-01

    Scrap-borne zinc and lead are enriched in the electric arc furnace dusts. Its Pb/Zn content of over 20% renders the dumping of this dust impossible in many countries, for both statutory and financial reasons. The Waelz process is the only reliable large-scale method for processing such dusts. 45% of the total electric furnace dusts occurring throughout Europe are being processed in Waelz plants with several operating in the US. The dust is treated in a rotary kiln where it is heated to approximately 1,200 C. Lead and zinc are volatilized under reducing conditions and collected as fine dust from the off-gas by cooling. The Waelz oxide recovered in the off-gas filters contains approximately 55% Zn and up to 10% Pb, and is ideal feedstock for the Imperial Smelting furnace for lead/zinc recovery. The remaining slag is inert and unleachable so that it can be used as a building aggregate.

  11. Survey of Dust Production in Pebble Bed Reactors Cores

    SciTech Connect

    Joshua J. Cogliati; Abderafi M. Ougouag; Javier Ortensi

    2011-06-01

    Graphite dust produced via mechanical wear from the pebbles in a pebble bed reactor is an area of concern for licensing. Both the German pebble bed reactors produced graphite dust that contained activated elements. These activation products constitute an additional source term of radiation and must be taken under consideration during the conduct of accident analysis of the design. This paper discusses the available literature on graphite dust production and measurements in pebble bed reactors. Limited data is available on the graphite dust produced from the AVR and THTR-300 pebble bed reactors. Experiments that have been performed on wear of graphite in pebble-bed-like conditions are reviewed. The calculation of contact forces, which are a key driving mechanism for dust in the reactor, are also included. In addition, prior graphite dust predictions are examined, and future areas of research are identified.

  12. Investigating A Novel Flame Retardant Known as V6: Measurements in Baby Products, House Dust and Car Dust

    PubMed Central

    Fang, Mingliang; Webster, Thomas F.; Gooden, David; Cooper, Ellen M.; McClean, Michael D.; Carignan, Courtney; Makey, Colleen; Stapleton, Heather M.

    2013-01-01

    With the phase-out of polybrominated diphenyl ether (PBDE) flame retardants, the use of new and alternate flame retardants has been increasing. 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate, known as V6, is a flame retardant applied to polyurethane foam commonly found in furniture and automobile foam. However, to the authors’ knowledge, no research has been conducted on V6 levels in the environment. The intention of this study was to measure the concentration of V6 in foam collected from baby products where it was recently detected, and measure levels in dust samples collected from homes and automobiles in the Boston, MA area. To accomplish this a pure V6 commercial standard was purchased from a Chinese manufacturer and purified (> 98%). An analytical method to measure V6 in dust samples using liquid chromatography tandem mass spectrometry (LC/MS-MS) was developed. Extraction was conducted using Accelerated Solvent Extraction (ASE) and extracts were purified using an ENVI-Florisil SPE column (500 mg, 3mL). V6 was measured in foam samples collected from baby products with a concentration ranging from 24,500,000 to 59,500,000 ng/g of foam (n = 12, average ± sd: 46,500,000 ± 12,000,000 ng/g; i.e., on average, 4.6 % of the foam mass was V6). V6 was also detected in 19 of 20 car dust samples and 14 of 20 house dust samples analyzed. The concentration of V6 in the house dust ranged from < 5 ng/g to 1,110 ng/g with a median of 12.5 ng/g, and < 5 ng/g to 6,160 ng/g in the car dust with a median of 103.0 ng/g. Concentrations in car dust were significantly higher than the house dust, potentially indicating higher use of V6 in automobiles compared to products found in the home. Furthermore, tris (2-chloroethyl) phosphate (TCEP), a known carcinogen, was found in the V6 commercial mixture (14% by weight) as an impurity and was consistently detected with V6 in the foam samples analyzed. A significant correlation was also observed between V6 and

  13. Investigating a novel flame retardant known as V6: measurements in baby products, house dust, and car dust.

    PubMed

    Fang, Mingliang; Webster, Thomas F; Gooden, David; Cooper, Ellen M; McClean, Michael D; Carignan, Courtney; Makey, Colleen; Stapleton, Heather M

    2013-05-01

    With the phase-out of polybrominated diphenyl ether (PBDE) flame retardants, the use of new and alternate flame retardants has been increasing. 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate, known as V6, is a flame retardant applied to polyurethane foam commonly found in furniture and automobile foam. However, to the authors' knowledge, no research has been conducted on V6 levels in the environment. The intention of this study was to measure the concentration of V6 in foam collected from baby products where it was recently detected and measure levels in dust samples collected from homes and automobiles in the Boston, MA area. To accomplish this, a pure V6 commercial standard was purchased from a Chinese manufacturer and purified (>98%). An analytical method to measure V6 in dust samples using liquid chromatography tandem mass spectrometry (LC/MS-MS) was developed. Extraction was conducted using accelerated solvent extraction (ASE) and extracts were purified using an ENVI-Florisil SPE column (500 mg, 3 mL). V6 was measured in foam samples collected from baby products with a concentration ranging from 24,500,000 to 59,500,000 ng/g of foam (n = 12, average ± sd: 46,500,000 ± 12,000,000 ng/g; i.e., on average, 4.6% of the foam mass was V6). V6 was also detected in 19 of 20 car dust samples and 14 of 20 house dust samples analyzed. The concentration of V6 in the house dust ranged from <5 ng/g to 1110 ng/g with a median of 12.5 ng/g, and <5 ng/g to 6160 ng/g in the car dust with a median of 103.0 ng/g. Concentrations in car dust were significantly higher than in the house dust potentially indicating higher use of V6 in automobiles compared to products found in the home. Furthermore, tris (2-chloroethyl) phosphate (TCEP), a known carcinogen, was found in the V6 commercial mixture (14% by weight) as an impurity and was consistently detected with V6 in the foam samples analyzed. A significant correlation was also observed between V6 and TCEP in

  14. Processing electric arc furnace dust into saleable chemical products

    SciTech Connect

    1998-04-01

    The modern steel industry uses electric arc furnace (EAF) technology to manufacture steel. A major drawback of this technology is the production of EAF dust, which is listed by the U.S. Environmental Protection Agency as a hazardous waste under the Resource Conservation and Recovery Act. The annual disposal of approximately 0.65 million tons of EAF dust in the United States and Canada is an expensive, unresolved problem for the steel industry. EAF dust byproducts are generated during the manufacturing process by a variety of mechanisms. The dust consists of various metals (e.g., zinc, lead, cadmium) that occur as vapors at 1,600{degrees}C (EAF hearth temperature); these vapors are condensed and collected in a baghouse. The production of one ton of steel will generate approximately 25 pounds of EAF dust as a byproduct, which is currently disposed of in landfills.

  15. Measurement of macrocyclic trichothecene in floor dust of water-damaged buildings using gas chromatography/tandem mass spectrometry-dust matrix effects.

    PubMed

    Saito, Rena; Park, Ju-Hyeong; LeBouf, Ryan; Green, Brett J; Park, Yeonmi

    2016-06-01

    Gas chromatography-tandem mass spectrometry (GC-MS/MS) was used to detect fungal secondary metabolites. Detection of verrucarol, the hydrolysis product of Stachybotrys chartarum macrocyclic trichothecene (MCT), was confounded by matrix effects associated with heterogeneous indoor environmental samples. In this study, we examined the role of dust matrix effects associated with GC-MS/MS to better quantify verrucarol in dust as a measure of total MCT. The efficiency of the internal standard (ISTD, 1,12-dodecanediol), and application of a matrix-matched standard correction method in measuring MCT in floor dust of water-damaged buildings was additionally examined. Compared to verrucarol, ISTD had substantially higher matrix effects in the dust extracts. The results of the ISTD evaluation showed that without ISTD adjustment, there was a 280% ion enhancement in the dust extracts compared to neat solvent. The recovery of verrucarol was 94% when the matrix-matched standard curve without the ISTD was used. Using traditional calibration curves with ISTD adjustment, none of the 21 dust samples collected from water damaged buildings were detectable. In contrast, when the matrix-matched calibration curves without ISTD adjustment were used, 38% of samples were detectable. The study results suggest that floor dust of water-damaged buildings may contain MCT. However, the measured levels of MCT in dust using the GC-MS/MS method could be significantly under- or overestimated, depending on the matrix effects, the inappropriate ISTD, or combination of the two. Our study further shows that the routine application of matrix-matched calibration may prove useful in obtaining accurate measurements of MCT in dust derived from damp indoor environments, while no isotopically labeled verrucarol is available. PMID:26853932

  16. Sixteen Years of Ulysses Interstellar Dust Measurements in the Solar System. I. Mass Distribution and Gas-to-dust Mass Ratio

    NASA Astrophysics Data System (ADS)

    Krüger, Harald; Strub, Peter; Grün, Eberhard; Sterken, Veerle J.

    2015-10-01

    In the early 1990s, contemporary interstellar dust penetrating deep into the heliosphere was identified with the in situ dust detector on board the Ulysses spacecraft. Between 1992 and the end of 2007 Ulysses monitored the interstellar dust stream. The interstellar grains act as tracers of the physical conditions in the local interstellar medium (ISM) surrounding our solar system. Earlier analyses of the Ulysses interstellar dust data measured between 1992 and 1998 implied the existence of a population of “big” interstellar grains (up to 10-13 kg). The derived gas-to-dust-mass ratio was smaller than the one derived from astronomical observations, implying a concentration of interstellar dust in the very local ISM. In this paper we analyze the entire data set from 16 yr of Ulysses interstellar dust measurements in interplanetary space. This paper concentrates on the overall mass distribution of interstellar dust. An accompanying paper investigates time-variable phenomena in the Ulysses interstellar dust data, and in a third paper we present the results from dynamical modeling of the interstellar dust flow applied to Ulysses. We use the latest values for the interstellar hydrogen and helium densities, the interstellar helium flow speed of {v}{ISM∞ }=23.2 {km} {{{s}}}-1, and the ratio of radiation pressure to gravity, β, calculated for astronomical silicates. We find a gas-to-dust mass ratio in the local interstellar cloud of {R}{{g}/{{d}}}={193}-57+85, and a dust density of (2.1 ± 0.6) × 10-24 kg m-3. For a higher inflow speed of 26 {km} {{{s}}}-1, the gas-to-dust mass ratio is 20% higher, and, accordingly, the dust density is lower by the same amount. The gas-to-dust mass ratio derived from our new analysis is compatible with the value most recently determined from astronomical observations. We confirm earlier results that the very local ISM contains “big” (i.e., ≈1 μm sized) interstellar grains. We find a dust density in the local ISM that is a

  17. East Asia Dust Source Location Using the Naval Research Laboratory's 1-km Dust Enhancement Product

    NASA Astrophysics Data System (ADS)

    Walker, A. L.; Curtis, C. A.; Miller, S. D.; Richardson, K.; Westphal, D. L.

    2011-12-01

    In the effort to predict dust storms and their effects on local, regional and global scales an often cited uncertainty is the precise location of dust sources. Many approaches have been used to identify major dust source regions in East Asia. These approaches include analysis of station data for frequency of dust storms, drifting dust, dusty day, wind speed, and PM10 total suspended particulates. Some approaches emphasize the location of land surface type (Gobi, sandy desert, and loess) and geomorphological setting/features (basins, plateaus, alluvial fans, dry rivers, or oases). Other approaches use remote sensing to locate areas of high dust activity using the Total Ozone Mapping Spectrometer Aerosol Index (TOMS AI) data, to correlate Normalized Difference Vegetation Index (NDVI) vegetation cover with dust storm frequency, or to track dust storm event origination by analyzing Moderate Resolution Imaging Spectroradiometer (MODIS) images. It is also customary for researchers to combine two or more of these approaches to identify dust source regions. In this paper we use a novel approach to locate dust sources in East Asia. Utilizing the Naval Research Laboratory's satellite derived 1-km Dust Enhancement Product (DEP) imagery we can readily distinguish elevated dust over land from other components of the scene and individual dust plumes are readily seen. The high resolution of the DEP allows the many small, eroding point sources (measuring 1-10s km across) that form individual plumes to be located. Five years (2007 - 2011) of East Asia DEP imagery have been analyzed. Dust source frequency plots will be shown highlighting the most active dust source areas in East Asia. Our results show the most active point sources are located along the slopes and around the rim of large basins. Within basins, on plateaus and in valleys point sources are concentrated in smaller depressions relative to the surrounding topography. Point sources are also associated with the action of

  18. Measurements of respirable dust and nanoparticle concentrations in a titanium dioxide pigment production factory.

    PubMed

    Huang, Cheng-Hsiung; Tai, Chih-Yuan; Huang, Cheng-Yu; Tsai, Chuen-Jinn; Chen, Chun-Wan; Chang, Cheng-Ping; Shih, Tung-Sheng

    2010-08-01

    This study compared respirable dust and nanoparticle concentrations measured by different sampling devices at a titanium dioxide pigment factory. Respirable particle mass concentrations, nanoparticle concentrations, particle size distribution and particle metallic content were measured at different sampling locations. The sampling results of the Multi-orifice Uniform Deposit Impactor (MOUDI) showed that the particle size distribution at this titanium dioxide production factory fell in the range of 1-10 mu m. Generally, the higher levels of the respirable particle mass concentrations and nanoparticle number concentrations were near the packing site of the pigment titanium dioxide production factory. Metal analysis results revealed that the titanium dioxide concentrations in respirable dust and nanoparticles were within the limits specified by National Institute for Occupational Safety and Health (NIOSH). During sampling, particle metallic content analysis is essential for identifying the source of particles and for measuring respirable dust and nanoparticle concentrations. PMID:20623401

  19. Wood dust particle and mass concentrations and filtration efficiency in sanding of wood materials.

    PubMed

    Welling, Irma; Lehtimäki, Matti; Rautio, Sari; Lähde, Tero; Enbom, Seppo; Hynynen, Pasi; Hämeri, Kaarle

    2009-02-01

    The importance of fine particles has become apparent as the knowledge of their effects on health has increased. Fine particle concentrations have been published for outside air, plasma arc cutting, welding, and grinding, but little data exists for the woodworking industry. Sanding was evaluated as the producer of the woodworking industry's finest particles, and was selected as the target study. The number of dust particles in different particle size classes and the mass concentrations were measured in the following environments: workplace air during sanding in plywood production and in the inlet and return air; in the dust emission chamber; and in filter testing. The numbers of fine particles were low, less than 10(4) particles/cm(3) (10(7) particles/L). They were much lower than typical number concentrations near 10(6) particles/cm(3) measured in plasma arc cutting, grinding, and welding. Ultrafine particles in the size class less than 100 nm were found during sanding of MDF (medium density fiberboard) sheets. When the cleaned air is returned to the working areas, the dust content in extraction systems must be monitored continuously. One way to monitor the dust content in the return air is to use an after-filter and measure pressure drop across the filter to indicate leaks in the air-cleaning system. The best after-filtration materials provided a clear increase in pressure drop across the filter in the loading of the filter. The best after-filtration materials proved to be quite effective also for fine particles. The best mass removal efficiencies for fine particles around 0.3 mum were over 80% for some filter materials loaded with sanding wood dust. PMID:19065389

  20. THE OBSERVED RELATION BETWEEN STELLAR MASS, DUST EXTINCTION, AND STAR FORMATION RATE IN LOCAL GALAXIES

    SciTech Connect

    Zahid, H. J.; Kewley, L. J.; Kudritzki, R. P.; Yates, R. M.

    2013-02-15

    In this study, we investigate the relation between stellar mass, dust extinction, and star formation rate (SFR) using {approx}150,000 star-forming galaxies from SDSS DR7. We show that the relation between dust extinction and SFR changes with stellar mass. For galaxies at the same stellar mass, dust extinction is anti-correlated with the SFR at stellar masses <10{sup 10} M {sub Sun }. There is a sharp transition in the relation at a stellar mass of 10{sup 10} M {sub Sun }. At larger stellar masses, dust extinction is positively correlated with the SFR for galaxies at the same stellar mass. The observed relation between stellar mass, dust extinction, and SFR presented in this study helps to confirm similar trends observed in the relation between stellar mass, metallicity, and SFR. The relation reported in this study provides important new constraints on the physical processes governing the chemical evolution of galaxies. The correlation between SFR and dust extinction for galaxies with stellar masses >10{sup 10} M {sub Sun} is shown to extend to the population of quiescent galaxies suggesting that the physical processes responsible for the observed relation between stellar mass, dust extinction, and SFR may be related to the processes leading to the shutdown of star formation in galaxies.

  1. The determination of cloud masses and dust characteristics from submillimetre thermal emission

    NASA Technical Reports Server (NTRS)

    Hildebrand, R. H.

    1983-01-01

    The principles by which the dust and masses and total masses of interstellar clouds and certain characteristics of interstellar dust grains can be derived from observations of far infrared and submillimeter thermal emission are reviewed. To the extent possible, the discussion will be independent of particular grain models.

  2. Uncertainty in Modeling Dust Mass Balance and Radiative Forcing from Size Parameterization

    SciTech Connect

    Zhao, Chun; Chen, Siyu; Leung, Lai-Yung R.; Qian, Yun; Kok, Jasper; Zaveri, Rahul A.; Huang, J.

    2013-11-05

    This study examines the uncertainties in simulating mass balance and radiative forcing of mineral dust due to biases in the aerosol size parameterization. Simulations are conducted quasi-globally (180oW-180oE and 60oS-70oN) using the WRF24 Chem model with three different approaches to represent aerosol size distribution (8-bin, 4-bin, and 3-mode). The biases in the 3-mode or 4-bin approaches against a relatively more accurate 8-bin approach in simulating dust mass balance and radiative forcing are identified. Compared to the 8-bin approach, the 4-bin approach simulates similar but coarser size distributions of dust particles in the atmosphere, while the 3-mode pproach retains more fine dust particles but fewer coarse dust particles due to its prescribed og of each mode. Although the 3-mode approach yields up to 10 days longer dust mass lifetime over the remote oceanic regions than the 8-bin approach, the three size approaches produce similar dust mass lifetime (3.2 days to 3.5 days) on quasi-global average, reflecting that the global dust mass lifetime is mainly determined by the dust mass lifetime near the dust source regions. With the same global dust emission (~6000 Tg yr-1), the 8-bin approach produces a dust mass loading of 39 Tg, while the 4-bin and 3-mode approaches produce 3% (40.2 Tg) and 25% (49.1 Tg) higher dust mass loading, respectively. The difference in dust mass loading between the 8-bin approach and the 4-bin or 3-mode approaches has large spatial variations, with generally smaller relative difference (<10%) near the surface over the dust source regions. The three size approaches also result in significantly different dry and wet deposition fluxes and number concentrations of dust. The difference in dust aerosol optical depth (AOD) (a factor of 3) among the three size approaches is much larger than their difference (25%) in dust mass loading. Compared to the 8-bin approach, the 4-bin approach yields stronger dust absorptivity, while the 3-mode

  3. Regional Modeling of Dust Mass Balance and Radiative Forcing over East Asia using WRF-Chem

    SciTech Connect

    Chen, Siyu; Zhao, Chun; Qian, Yun; Leung, Lai-Yung R.; Huang, J.; Huang, Zhongwei; Bi, Jianrong; Zhang, Wu; Shi, Jinsen; Yang, Lei; Li, Deshuai; Li, Jinxin

    2014-12-01

    The Weather Research and Forecasting model with Chemistry (WRF-Chem) is used to investigate the seasonal and annual variations of mineral dust over East Asia during 2007-2011, with a focus on the dust mass balance and radiative forcing. A variety of measurements from in-stu and satellite observations have been used to evaluate simulation results. Generally, WRF-Chem reproduces not only the column variability but also the vertical profile and size distribution of mineral dust over and near the dust source regions of East Asia. We investigate the dust lifecycle and the factors that control the seasonal and spatial variations of dust mass balance and radiative forcing over the seven sub-regions of East Asia, i.e. source regions, the Tibetan Plateau, Northern China, Southern China, the ocean outflow region, and Korea-Japan regions. Results show that, over the source regions, transport and dry deposition are the two dominant sinks. Transport contributes to ~30% of the dust sink over the source regions. Dust results in a surface cooling of up to -14 and -10 W m-2, atmospheric warming of up to 20 and 15 W m-2, and TOA cooling of -5 and -8 W m-2 over the two major dust source regions of East Asia, respectively. Over the Tibetan Plateau, transport is the dominant source with a peak in summer. Over identified outflow regions, maximum dust mass loading in spring is contributed by the transport. Dry and wet depositions are the comparably dominant sinks, but wet deposition is larger than dry deposition over the Korea-Japan region, particularly in spring (70% versus 30%). The WRF-Chem simulations can generally capture the measured features of dust aerosols and its radaitve properties and dust mass balance over East Asia, which provides confidence for use in further investigation of dust impact on climate over East Asia.

  4. The Chemical Composition and Gas-to-Dust Mass Ratio of Nearby Interstellar Matter

    NASA Technical Reports Server (NTRS)

    Frisch, Priscilla C.; Slavin, Jonathan D.

    2003-01-01

    We use recent results on interstellar gas toward nearby stars and interstellar by-products within the solar system to select among the equilibrium radiative transfer models of the nearest interstellar material presented in Slavin & Frisch. For the assumption that O/H - 400 parts per million, models 2 and 8 are found to yield good fits to available data on interstellar material inside and outside of the heliosphere, with the exception of the Ne abundance in the pickup ion and anomalous cosmic-ray populations. For these models, the interstellar medium (ISM) at the entry point to the heliosphere has n(H(sup 0)) = 0.202-0.208/cu cm, n(He(sup 0) = 0.0137-0.0152/cu cm, and ionizations X(H) = 0.29-0.30, X(He) = 0.47-0.51. These best models suggest that the chemical composition of the nearby ISM is approx.60%-70% subsolar if S is undepleted. Both H(0) and H(+) need to be included when evaluating abundances of ions found in warm diffuse clouds. Models 2 and 8 yield an H filtration factor of approx.0.46. Gas-to-dust mass ratios for the ISM toward epsilon CMa are R(sub gd) = 178-183 for solar abundances of Holweger or R(sub gd) = 611-657 for an interstellar abundance standard 70% solar. Direct observations of dust grains in the solar system by Ulysses and Galileo yield R(sub gd) appr0x. 115 for models 2 and 8, supporting earlier results (Frisch and coworkers). If the local ISM abundances are subsolar, then gas and dust are decoupled over small spatial scales. The inferred variation in R(sub gd) over parsec length scales is consistent with the fact that the ISM near the Sun is part of a dynamically active cluster of cloudlets flowing away from the Sco-Cen association. Observations toward stars within approx.500 pc show that R(sub gd) correlates with the percentage of the dust mass that is carried by iron, suggesting that an Fe-rich grain core (by mass) remains after grain destruction. Evidently large dust grains (>10(exp -13) g) and small dust grains (<10(exp -13) g) are not

  5. Mechanics of aeolian processes: Soil erosion and dust production

    NASA Technical Reports Server (NTRS)

    Mehrabadi, M. M.

    1989-01-01

    Aeolian (wind) processes occur as a result of atmosphere/land-surface system interactions. A thorough understanding of these processes and their physical/mechanical characterization on a global scale is essential to monitoring global change and, hence, is imperative to the fundamental goal of the Earth observing system (Eos) program. Soil erosion and dust production by wind are of consequence mainly in arid and semi arid regions which cover 36 percent of the Earth's land surface. Some recent models of dust production due to wind erosion of agricultural soils and the mechanics of wind erosion in deserts are reviewed and the difficulties of modeling the aeolian transport are discussed.

  6. NGC 4370: a case study for testing our ability to infer dust distribution and mass in nearby galaxies

    NASA Astrophysics Data System (ADS)

    Viaene, S.; De Geyter, G.; Baes, M.; Fritz, J.; Bendo, G. J.; Boquien, M.; Boselli, A.; Bianchi, S.; Cortese, L.; Côté, P.; Cuillandre, J.-C.; De Looze, I.; di Serego Alighieri, S.; Ferrarese, L.; Gwyn, S. D. J.; Hughes, T. M.; Pappalardo, C.

    2015-07-01

    Context. A segment of the early-type galaxy population hosts a prominent dust lane, often decoupled from its stellar body. Methods of quantifying the dust content of these systems based on optical imaging data usually yield dust masses that are an order of magnitude lower than dust masses derived from the observed far-IR (FIR) emission. The discrepancy is often explained by invoking a diffuse dust component that is hard to trace in the UV or optical. Aims: High-quality optical data from the Next Generation Virgo cluster Survey (NGVS) and FIR/sub-mm observations from the Herschel Virgo Cluster Survey (HeViCS) allow us to revisit previous methods of determining the dust content in galaxies and explore new ones. NGC 4370 is an edge-on, early-type galaxy with a conspicuous dust lane and regular morphology, making it suitable for several (semi-)analytical modelling techniques. We aim to derive the dust mass from both optical and FIR data and to investigate the need to invoke a putative diffuse dust component. Methods: We used different methods to determine the total dust mass in the dust lane. We used our exquisite optical data to create colour and attenuation maps, which are converted to approximate dust mass maps based on simple dust geometries. Dust masses were also derived from SED fits to FIR to sub-mm observations. Finally, inverse radiative transfer fitting was performed to investigate more complex dust geometries, such as an exponential dust disc and a dust ring and to treat the dust-starlight interaction in a self-consistent way. Results: We find that the empirical methods applied to the optical data yield lower limits of 3.4 × 105 M⊙, an order of magnitude below the total dust masses derived from SED fitting. In contrast, radiative transfer models yield dust masses that are slightly lower, but fully consistent with the FIR-derived mass. We find that the effect of a nuclear stellar disc on the derivation of the total dust mass is minor. Conclusions: Dust is

  7. Halley comet dust particle classification according to the data obtained by mass spectrometer Puma-2

    NASA Astrophysics Data System (ADS)

    Dikov, Yu. P.; Evlanov, E. N.; Fomenkova, M. N.; Mukhin, L. M.; Nazarov, M. A.; Prilutsky, O. F.; Sagdeev, R. Z.; Zubkov, B. V.

    Nonzero mode spectra of the dust component of Comet Halley obtained by the dust particle impact mass-spectrometer, Puma-1, on Vega, are used to examine the origin of the mineral phase. The element compositions of 511 cometary particles are studied, using data on ions of Na, Ca, C, H, N, S, Si, Mg, Fe, Cr, and Al. The results are used to determine the mineral composition of the dust of Comet Halley.

  8. Black hole mass measurements using ionized gas discs: systematic dust effects

    SciTech Connect

    Baes, Maarten

    2008-10-08

    Using detailed Monte Carlo radiative transfer simulations in realistic models for galactic nuclei, we investigate the influence of interstellar dust in ionized gas discs on the rotation curves and the resulting black hole mass measurements. We find that absorption and scattering by interstellar dust leaves the shape of the rotation curves basically unaltered, but slightly decreases the central slope of the rotation curves. As a result, the ''observed'' black hole masses are systematically underestimated by some 10 to 20% for realistic optical depths. We therefore argue that the systematic effect of dust attenuation should be taken into account when estimating SMBH masses using ionized gas kinematics.

  9. Tungsten dust in fusion tokamaks: relevant dust laser production, characterization and behaviour under tritium loading

    NASA Astrophysics Data System (ADS)

    Bernard, E.; Delaporte, P.; Jambon, F.; Rousseau, B.; Grisolia, C.; Chaudanson, D.; Nitsche, S.

    2016-02-01

    In this paper, production and study of tokamak relevant W particles is presented. Existing tokamak-produced dust being very scarce, extensive study of such nano-particles with high specific surface area (SSA) and sub micron size requires a specific and efficient alternative production technique, in order to obtain relevant particles to study. We present our production and collection setup based on pulsed laser ablation on bulk ITER-grade tungsten, and the various parameters impacting on the collected dust morphology and properties. We observed that optimum gas pressure is required to control the laser-induced plasma properties and favour the production of tungsten nano-particles with high SSA. The laser pulse duration is also a key parameter to limit the generation of tungsten liquid droplets during the ablation process. The nano-particules structure and general aspect are characterized via scanning electron microscopy and transmission electron microscopy. Lastly, this dust produced by laser ablation is loaded with tritium by gas exposure, and its retention capability and long-term evolution addressed and compared to metallurgically produced W powders with homogeneous size distribution.

  10. Insect mass production technologies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insects provide a very promising alternative for the future production of animal protein. Their nutritional value in conjunction with their food conversion efficiency and low water requirements, make them a more sustainable choice for the production of food and animal origin. However, to realize the...

  11. Pacific patterns of dust deposition, iron supply and export production

    NASA Astrophysics Data System (ADS)

    Winckler, G.; Anderson, R. F.; Park, J.; Schwartz, R.; Pahnke, K.; Struve, T.; Lamy, F.; Gersonde, R.

    2015-12-01

    The scarcity of iron limits marine export production and carbon uptake in about a quarter of the global ocean where the surface concentration of nitrate and phosphate is high, as biological utilization of these macronutrients is incomplete. Of these high nutrient low chlorophyll (HNLC) regions, the Southern Ocean is the region where variations in iron availability can have the largest effect on Earth's carbon cycle through its fertilizing effect on marine ecosystems, both in the modern and in the past. Recent work in the Subantarctic South Atlantic (Martínez-Garcia et al., 2009, 2014, Anderson et al., 2014) suggests that dust-driven iron fertilization lowered atmospheric CO2 by up to 40 ppm in the latter half of each glacial cycle of the late Pleistocene, with the increase in Subantarctic productivity consuming a greater fraction of the surface nutrients and thus driving more storage of carbon in the ocean interior. The other sectors of the Southern Ocean remain poorly constrained, including the Pacific Sector, that accounts for the largest surface area of the Subantarctic Southern Ocean. Here we report records of dust deposition, iron supply and export production from a set of cores from the Subantarctic Pacific (PS75, Lamy et al 2014) and initial results about the origin of dust transported to the Subantarctic Pacific Ocean from radiogenic isotopes and rare earth elements. We test how tightly dust and biological productivity are coupled over glacial/interglacial and millennial timescales in the Subantarctic Pacific and place the region in a context of global patterns of biological productivity, nutrient utilization and iron fertilization by dust, including comparisons to the other Pacific HNLC regions, the Subarctic North Pacific and equatorial Pacific.

  12. Determination of minor elements in steelmaking flue dusts using laser ablation inductively coupled plasma mass spectrometry.

    PubMed

    Coedo, A G; Padilla, I; Dorado, M T

    2005-07-15

    Element determination in solid waste products from the steel industry usually involves the time-consuming step of preparing a solution of the solid. Laser ablation (LA) inductively coupled plasma mass spectrometry (ICP-MS) has been applied to the analysis of Cr, Ni, Cu, As, Cd and Sn, elements of importance from the point of view of their impact on the environment, in electric arc furnace flue dust (EAFD). A simple method of sample preparation as pressed pellets using a mixture of cellulose and paraffin as binder material was applied. Calibration standards were prepared spiking multielement solution standards to a 1:1 ZnO+Fe(2)O(3) synthetic matrix. The wet powder was dried and mechanically homogenised. Quantitative analysis were based on external calibration using a set of matrix matched calibration standards with Rh as a internal standard. Results obtained using only one-point for calibration without matrix matched, needing less time for standardization and data processing, are also presented. Data are calculated for flue dust reference materials: CRM 876-1 (EAFD), AG-6203 (EAFD), AG-6201 (cupola dust) and AG-SX3705 (coke ashes), and for two representative electrical arc furnace flue dusts samples from Spanish steelmaking companies: MS-1 and MS-2. For the reference materials, an acceptable agreement with certificate values was achieved, and the results for the MS samples matched with those obtained from conventional nebulization solutions (CN). The analytical precision was found to be better than 7% R.S.D. both within a single pellet and between several pellets of the same sample for all the elements. PMID:18970147

  13. Composition of Exogenous Dust at Saturn from Cassini-CDA Mass Spectra

    NASA Astrophysics Data System (ADS)

    Postberg, Frank; Altobelli, N.; Fiege, K.; Hillier, J. K.; Kempf, S.; Srama, R.; Trieloff, M.

    2013-10-01

    Over 99% of impact ionization mass spectra recorded by Cassini’s Cosmic Dust Analyser (CDA) at Saturn are water dominated E-ring grains. However, there are hundreds of spectra that indicate a purely mineral composition. A thorough search combining directional and velocity information show that a substantial part of these non-water particles must be originated from outside the Saturnian system. Here we report of a refined investigation of the composition of the exogenous dust by CDA’s time-of-flight mass spectrometer. A comprehensive data set from the latest CDA observational campaigns for the first time allow detailed insights into the composition of endogenous and exogenous non-water dust populations. Interstellar dust (ISD) particles crossing the Saturnian system could be dynamically and compositionally separated. The ISD spectra exhibit a surprisingly homogenous silicateous composition which is quite distinct from the non-water dust bound to the Saturnian system.

  14. The impact of Saharan dust events on long-term glacier mass balance in the Alps

    NASA Astrophysics Data System (ADS)

    Bauder, A.; Gabbi, J.; Huss, M.; Schwikowski, M.

    2014-12-01

    Saharan dust falls are frequently observed in the Alpine region and are easily recognized by the unique yellowish coloration of the snow surface. Such Saharan dust events contribute to a large part to the total mineral dust deposited in snow and impact the surface energy budget by reducing the snow and ice albedo. In this study we investigate the long-term effect of such Saharan dust events on the surface albedo and the glacier's mass balance. The analysis is performed over the period 1914-2013 for two field sites on Claridenfirn, Swiss Alps, where an outstanding 100-year record of seasonal mass balance measurements is available. Based on the detailed knowledge about the mass balance, annual melt and accumulation rates are derived. A firn/ice core drilled at the glacier saddle of Colle Gnifetti (Swiss Alps) provides information on the impurity concentration in precipitation over the last century. A mass balance model combined with a parameterization for snow and ice albedo based on the specific surface area of snow and the snow impurity concentration is employed to assess the dust-albedo feedback. In order to track the position and thickness of snow layers a snow density model is implemented. Atmospheric dust enters the system of snow layers by precipitation and remains in the corresponding layer as long as there is no melt. When melt occurs, the water-insoluble part of the dust of the melted snow is supposed to accumulate in the top surface layer. The upper site has experienced only positive net mass balance and dust layers are continuously buried so that the impact of strong Saharan dust events is mainly restricted to the corresponding year. In the case of the lower site, the surface albedo is more strongly influenced by dust events of previous years due to periods with negative mass balances. Model results suggest that the enhanced melting in the 1940s yield even higher dust concentrations in 1947 compared to years with exceptional high Saharan dust deposition

  15. The origin of low mass particles within and beyond the dust coma envelopes of Comet Halley

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Rabinowitz, D.; Tuzzolino, A. J.; Ksanfomality, L. V.; Sagdeev, R. Z.

    1987-01-01

    Measurements from the Dust Counter and Mass Analyzer (DUCMA) instruments on VEGA-1 and -2 revealed unexpected fluxes of low mass (up to 10 to the minus 13th power g) dust particles at very great distances from the nucleus (300,000 to 600,000 km). These particles are detected in clusters (10 sec duration), preceded and followed by relatively long time intervals during which no dust is detected. This cluster phenomenon also occurs inside the envelope boundaries. Clusters of low mass particles are intermixed with the overall dust distribution throughout the coma. The clusters account for many of the short-term small-scale intensity enhancements previously ascribed to microjets in the coma. The origin of these clusters appears to be emission from the nucleus of large conglomerates which disintegrate in the coma to yield clusters of discrete, small particles continuing outward to the distant coma.

  16. Back-trajectory model of the Saharan dust flux and particle mass distribution in West Africa

    NASA Astrophysics Data System (ADS)

    Sunnu, Albert; Resch, Francois; Afeti, George

    2013-06-01

    A back trajectory model of the Sahara dust flux toward the Gulf of Guinea has been studied. First, the atmospheric circulation over North and West Africa in winter is obtained by the backward trajectory plots with NOAA HYSPLIT to establish the winds responsible for the dust transport. The 'box' model derived by Resch et al. (2007) is used to develop the back trajectory model equations. The dust particle mass distributions at various locations traced back from Kumasi and Tamale to the Harmattan dust origin in the Chad basin can be obtained. The model is first tested with the particle mass concentrations at Tamale in Harmattan 2002 and 2005, which are easily deduced. Sample calculations are shown to illustrate the use of the model to estimate the particle mass concentration distributions at Kano and Maiduguri in Nigeria during the Harmattan 2002 and 2005.

  17. A STUBBORNLY LARGE MASS OF COLD DUST IN THE EJECTA OF SUPERNOVA 1987A

    SciTech Connect

    Matsuura, M.; Barlow, M. J.; Dwek, E.; Babler, B.; Baes, M.; Fritz, Jacopo; Meixner, M.; Cernicharo, José; Clayton, Geoff C.; Dunne, L.; Fransson, C.; Lundqvist, P.; Gear, Walter; Gomez, H. L.; Groenewegen, M. A. T.; Indebetouw, R.; Ivison, R. J.; Jerkstrand, A.; Lebouteiller, V.; and others

    2015-02-10

    We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 μm data and improved imaging quality at 100 and 160 μm compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 μm [O I] line flux, eliminating the possibility that line contaminations distort the previously estimated dust mass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 μm flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 ± 0.1 M {sub ☉} of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3 M {sub ☉} of amorphous carbon and 0.5 M {sub ☉} of silicates, totalling 0.8 M {sub ☉} of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies.

  18. The Importance of Physical Models for Deriving Dust Masses and Grain Size Distributions in Supernova Ejecta. I. Radiatively Heated Dust in the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Temim, Tea; Dwek, Eli

    2013-01-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 Solar Mass, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 micron. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in

  19. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: SYNTECH PRODUCTS CORPORATION'S TECHSUPPRESS

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  20. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: SYNTECH PRODUCTS CORPORATION'S PETROTAC

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  1. THE IMPORTANCE OF PHYSICAL MODELS FOR DERIVING DUST MASSES AND GRAIN SIZE DISTRIBUTIONS IN SUPERNOVA EJECTA. I. RADIATIVELY HEATED DUST IN THE CRAB NEBULA

    SciTech Connect

    Temim, Tea; Dwek, Eli

    2013-09-01

    Recent far-infrared (IR) observations of supernova remnants (SNRs) have revealed significantly large amounts of newly condensed dust in their ejecta, comparable to the total mass of available refractory elements. The dust masses derived from these observations assume that all the grains of a given species radiate at the same temperature, regardless of the dust heating mechanism or grain radius. In this paper, we derive the dust mass in the ejecta of the Crab Nebula, using a physical model for the heating and radiation from the dust. We adopt a power-law distribution of grain sizes and two different dust compositions (silicates and amorphous carbon), and calculate the heating rate of each dust grain by the radiation from the pulsar wind nebula. We find that the grains attain a continuous range of temperatures, depending on their size and composition. The total mass derived from the best-fit models to the observed IR spectrum is 0.019-0.13 M{sub Sun }, depending on the assumed grain composition. We find that the power-law size distribution of dust grains is characterized by a power-law index of 3.5-4.0 and a maximum grain size larger than 0.1 {mu}m. The grain sizes and composition are consistent with what is expected for dust grains formed in a Type IIP supernova (SN). Our derived dust mass is at least a factor of two less than the mass reported in previous studies of the Crab Nebula that assumed more simplified two-temperature models. These models also require a larger mass of refractory elements to be locked up in dust than was likely available in the ejecta. The results of this study show that a physical model resulting in a realistic distribution of dust temperatures can constrain the dust properties and affect the derived dust masses. Our study may also have important implications for deriving grain properties and mass estimates in other SNRs and for the ultimate question of whether SNe are major sources of dust in the Galactic interstellar medium and in

  2. SUDA: A Dust Mass Spectrometer for Compositional Surface Mapping for a Mission to Europa

    NASA Astrophysics Data System (ADS)

    Kempf, S.; Altobelli, N.; Briois, C.; Grün, E.; Horanyi, M.; Postberg, F.; Schmidt, J.; Srama, R.; Sternovsky, Z.; Tobie, G.; Zolotov, M.

    2014-04-01

    We developed a dust mass spectrometer to measure the composition of ballistic dust particles populating the thin exospheres that were detected around each of the Galilean moons. Since these grains are direct samples from the moons' icy surfaces, unique composition data will be obtained that will help to define and constrain the geological activities on and below the moons? surface. The proposed instrument will make a vital contribution to NASA's planned Europa Clipper mission and provide key answers to its main scientific questions about the surface composition, habitability, the icy crust, and exchange processes with the deeper interior of the Jovian icy moon Europa. The SUrface Dust Aanalyser (SUDA) is a time-offlight, reflectron-type impact mass spectrometer, optimised for a high mass resolution which only weakly depends on the impact location. The small size (268×250×171 mm3), low mass (< 4 kg) and large sensitive area (220 cm2) makes the instrument well suited for the challenging demands of the Europa Clipper mission. A full-size prototype SUDA instrument was built in order to demonstrate its performance through calibration experiments at the dust accelerator at NASA's IMPACT institute at Boulder, CO with a variety of cosmochemically relevant dust analogues. The effective mass resolution of m/∆m of 200-250 is achieved for mass range of interest m = 1-250.

  3. Measuring the Dust Flux and Dust Particle Mass Distribution in the Saturn Rings with HRD Dust Instrument on the Cassini Mission

    NASA Astrophysics Data System (ADS)

    Tuzzolino, A. J.; Economou, T. E.

    In July 2004, the Cassini spacecraft will go into the Saturn orbit and start a 4 year intensive investigation of the planet itself, its multiple satellites and its rings with a multinational instrument payload. The High Rate Detectors (HRD) instrument provided by the Laboratory of Astrophysics and Space Research of the University of is part of the German Cosmic Dust Analyzer (CDA) and its main scientific objective is to provide quantitative measurements and mass distributions of dust particles in the rings of Saturn in the 10-11 to 10-4 grams mass range. The HRD instrument consists of two dust detectors -- a 20 and a 200 cm2 polyvinylidene fluoride (PVDF) sensors -- and an electronic box that contains all the analog and digital electronics and in addition provides interface between the HRD and CDA instrument. The CDA stores all the HRD data in its memory and transmits the data to Earth. The HRD weighs 1.7 kg and consumes 1.8 W of power [1]. The HRD instrument was fully calibrated through the entire mass range using two dust particle accelerators at Heidelberg and Munich in Germany. The HRD electronics is very fast and it will provide spatial and time distributions of up to 0.1 second. It can handle rates up to 104 counts/sec expected to be encountered during the Saturn ring crossings without any dead time. The HRD instrument operated successfully during all of the time that it was under power and detected many interplanetary dust particles. Almost all of these particles were close to the lowest mass threshold. References 1 A.J. TUZZOLINO, T.E. ECONOMOU, R.B. MCKIBBEN, J.A. SIMPSON, J.A.M. MCDONNELL, M.J. BURCHELL, B.A.M. VAUGHAN, P. TSOU, M.S. HANNER, B.C. CLARK AND D.E. BROWNLEE. THE DUST FLUX MONITOR INSTRUMENT FOR THE STARDUST MISSION TO COMET WILD-2, J. GEOPHYS. RES., 108, DOI:10.1029/2003JE002091, 2003.

  4. Dust productivity and impact collision of the asteroid (596) Scheila

    NASA Astrophysics Data System (ADS)

    Neslusan, L.; Ivanova, O.; Husarik, M.; Svoren, J.; Krisandova, Z. Seman

    2016-06-01

    Photometric observations of asteroid (596) Scheila were obtained during and after its 2010 outburst. The estimated radius of the body (spherical approximation of the asteroidal body) was 51.2±3.0 km and 50.6±3.0 km for different methods. The ejected dust mass from the asteroid ranged from 2.5 ×107 to 3.4 ×107 kg for different methods. An impact mechanism for triggering Scheila's activity is discussed. A few days before the impact, Scheila passed through the corridors of two potential cometary streams.

  5. Accuracy of core mass estimates in simulated observations of dust emission

    NASA Astrophysics Data System (ADS)

    Malinen, J.; Juvela, M.; Collins, D. C.; Lunttila, T.; Padoan, P.

    2011-06-01

    Aims: We study the reliability of the mass estimates obtained for molecular cloud cores using sub-millimetre and infrared dust emission. Methods: We use magnetohydrodynamic simulations and radiative transfer to produce synthetic observations with spatial resolution and noise levels typical of Herschel surveys. We estimate dust colour temperatures using different pairs of intensities, calculate column densities with opacity at one wavelength, and compare the estimated masses with the true values. We compare these results to the case when all five Herschel wavelengths are available. We investigate the effects of spatial variations of dust properties and the influence of embedded heating sources. Results: Wrong assumptions of dust opacity and its spectral index β can cause significant systematic errors in mass estimates. These are mainly multiplicative and leave the slope of the mass spectrum intact, unless cores with very high optical depth are included. Temperature variations bias the colour temperature estimates and, in quiescent cores with optical depths higher than for normal stable cores, masses can be underestimated by up to one order of magnitude. When heated by internal radiation sources, the dust in the core centre becomes visible and the observations recover the true mass spectra. Conclusions: The shape, although not the position, of the mass spectrum is reliable against observational errors and biases introduced in the analysis. This changes only if the cores have optical depths much higher than expected for basic hydrostatic equilibrium conditions. Observations underestimate the value of β whenever there are temperature variations along the line of sight. A bias can also be observed when the true β varies with wavelength. Internal heating sources produce an inverse correlation between colour temperature and β that may be difficult to separate from any intrinsic β(T) relation of the dust grains. This suggests caution when interpreting the observed

  6. An Eddy-Diffusivity/Mass-Flux Turbulence Parameterization: Application to Dust Convection on Mars

    NASA Astrophysics Data System (ADS)

    Witek, M. L.; Teixeira, J.; Richardson, M. I.; Mischna, M. A.

    2014-12-01

    The Eddy-diffusivity/Mass-flux (EDMF) parameterization has been extremely successful in simulating the evolution of terrestrial atmospheric boundary layers. It is particularly suited for representing strong and moderate convection, where turbulence organizes in coherent structures and transports heat, humidity and pollution throughout the extent of the boundary layer. The EDMF's ability to explicitly represent turbulent updrafts and associated fluxes is key to a proper depiction of the thermodynamic structure of the atmosphere. It is the most appropriate tool currently available to address the outstanding issues in the Mars atmosphere and dust modeling on a global and regional scale. Dust is one of the most important moderators of the Martian climate. Basic theoretical arguments and observations such as high-altitude dust maxima, dust layering, and transport in plumes during dust storm onset—none of which are currently captured in general circulation models (GCMs)—all demonstrate the vital importance of representing dust vertical mixing by plumes. Most GCMs, however, only consider local, Mellor-Yamada-type diffusion, which is insufficient to capture the evolving dust distribution and hence the Martian climate system correctly. Here, we developed an EDMF parameterization for the Martian convective boundary layer. We report on details of the parameterization and its performance as compared against large-eddy simulations. We investigate a downdraft contribution to turbulent fluxes and the importance of mass-flux transport of TKE. Furthermore, we investigate the role of plume heating—through absorption of solar radiation by uplifted dust particles—on the plume evolution (a mechanisms that could act as a surrogate of the latent heat release in terrestrial clouds). Our results shed light on the reasons behind the presence of elevated dust layers in the Martian atmosphere.

  7. Comparison of a direct-reading device to gravimetric methods for evaluating organic dust aerosols in an enclosed swine production environment.

    PubMed

    Taylor, C D; Reynolds, S J

    2001-01-01

    The production of livestock in enclosed facilities has become an accepted practice, driven by the need for increased efficiency. Exposure to organic dusts, containing various bioactive components, has been identified an important risk factor for the high rate of lung disease found among workers in these environments. Assessment of organic dust exposure requires technical skills and instrumentation not readily available to most agricultural enterprises. Development of a simple, cost-effective method for measuring organic dust levels would be useful in evaluating and controlling exposures in these environments. The objective of this study was to evaluate the usefulness of the direct reading MIE PDM-3 Miniram for estimating organic dust concentrations in enclosed swine production facilities. Responses from the MIE PDM-3 Miniram were compared to gravimetric methods for total and inhalable dust. Total dust determinations were conducted in accordance with the National Institute for Occupational Safety and Health (NIOSH) method 0500. Inhalable particulate mass (IPM) sampling was conducted using SKC brand IOM (Institute of Occupational Medicine) sampling cassettes, which meet the American Conference of Governmental Industrial Hygienists ACGIH criteria for inhalable dust sampling. This study design also allowed for the comparison of traditional total dust method to the IPM method, in collecting organic dusts in an agricultural setting. Fifteen sets of side-by-side samples (Miniram, total dust, and IPM) were collected over a period of six months in a swine confinement building. There were statistically significant differences in the results provided by the three sampling methods. Measurements for inhalable dust exceeded those for total dust in eleven of fifteen samples. The Miniram time-weighted average (TWA) response to the organic dust was always the lower of the three methods. A high degree of correlation was found among all three methods. The Miniram performed well under

  8. Impact dust not the cause of the Cretaceous-Tertiary mass extinction

    NASA Astrophysics Data System (ADS)

    Pope, Kevin O.

    2002-02-01

    Most of the 3-mm-thick globally distributed Chicxulub ejecta layer found at the Cretaceous-Tertiary (K-T) boundary was deposited as condensation droplets from the impact vapor plume. A small fraction of this layer (<1%) is clastic debris. Theoretical calculations, coupled with observations of the coarse dust fraction, indicate that very little (<1014 g) was submicrometer-size dust. The global mass and grain-size distribution of the clastic debris indicate that stratospheric winds spread the debris from North America, over the Pacific Ocean, to Europe, and little debris reached high southern latitudes. These findings indicate that the original K-T impact extinction hypothesis—the shutdown of photosynthesis by submicrometer-size dust—is not valid, because it requires more than two orders of magnitude more fine dust than is estimated here. Furthermore, estimates of future impact hazards, which rely upon inaccurate impact-dust loadings, are greatly overstated.

  9. On the relationship between visual magnitudes and gas and dust production rates in target comets to space missions

    NASA Astrophysics Data System (ADS)

    de Almeida, A. A.; Sanzovo, G. C.; Singh, P. D.; Misra, A.; Miguel Torres, R.; Boice, D. C.; Huebner, W. F.

    In this paper, we report the results of a cometary research, developed during the last 10 years by us, involving a criterious analysis of gas and dust production rates in comets directly associated to recent space missions. For the determination of the water release rates we use the framework of the semi-empirical model of observed visual magnitudes [Newburn Jr., R.L. A semi-empirical photometric theory of cometary gas and dust production. Application to P/Halley's production rates, ESA-SP 174, 3, 1981; de Almeida, A.A., Singh, P.D., Huebner, W.F. Water release rates, active areas, and minimum nuclear radius derived from visual magnitudes of comets - an application to Comet 46P/Wirtanen, Planet. Space Sci. 45, 681-692, 1997; Sanzovo, G.C., de Almeida, A.A., Misra, A. et al. Mass-loss rates, dust particle sizes, nuclear active areas and minimum nuclear radii of target comets for missions STARDUST and CONTOUR, MNRAS 326, 852-868, 2001.], which once obtained, were directly converted into gas production rates. In turn, the dust release rates were obtained using the photometric model for dust particles [Newburn Jr., R.L., Spinrad, H. Spectrophotometry of seventeen comets. II - the continuum, AJ 90, 2591-2608, 1985; de Freitas Pacheco, J.A., Landaberry, S.J.C., Singh, P.D. Spectrophotometric observations of the Comet Halley during the 1985-86 apparition, MNRAS 235, 457-464, 1988; Sanzovo, G.C., Singh, P.D., Huebner, W.F. Dust colors, dust release rates, and dust-to-gas ratios in the comae of six comets, A&AS 120, 301-311, 1996.]. We applied these models to seven target comets, chosen for space missions of "fly-by"/impact and rendezvous/landing.

  10. Classification of Dust Days by Satellite Remotely Sensed Aerosol Products

    NASA Technical Reports Server (NTRS)

    Sorek-Hammer, M.; Cohen, A.; Levy, Robert C.; Ziv, B.; Broday, D. M.

    2013-01-01

    Considerable progress in satellite remote sensing (SRS) of dust particles has been seen in the last decade. From an environmental health perspective, such an event detection, after linking it to ground particulate matter (PM) concentrations, can proxy acute exposure to respirable particles of certain properties (i.e. size, composition, and toxicity). Being affected considerably by atmospheric dust, previous studies in the Eastern Mediterranean, and in Israel in particular, have focused on mechanistic and synoptic prediction, classification, and characterization of dust events. In particular, a scheme for identifying dust days (DD) in Israel based on ground PM10 (particulate matter of size smaller than 10 nm) measurements has been suggested, which has been validated by compositional analysis. This scheme requires information regarding ground PM10 levels, which is naturally limited in places with sparse ground-monitoring coverage. In such cases, SRS may be an efficient and cost-effective alternative to ground measurements. This work demonstrates a new model for identifying DD and non-DD (NDD) over Israel based on an integration of aerosol products from different satellite platforms (Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI)). Analysis of ground-monitoring data from 2007 to 2008 in southern Israel revealed 67 DD, with more than 88 percent occurring during winter and spring. A Classification and Regression Tree (CART) model that was applied to a database containing ground monitoring (the dependent variable) and SRS aerosol product (the independent variables) records revealed an optimal set of binary variables for the identification of DD. These variables are combinations of the following primary variables: the calendar month, ground-level relative humidity (RH), the aerosol optical depth (AOD) from MODIS, and the aerosol absorbing index (AAI) from OMI. A logistic regression that uses these variables, coded as binary

  11. The gas-to-dust mass ratio of Centaurus A as seen by Herschel

    NASA Astrophysics Data System (ADS)

    Parkin, T. J.; Wilson, C. D.; Foyle, K.; Baes, M.; Bendo, G. J.; Boselli, A.; Boquien, M.; Cooray, A.; Cormier, D.; Davies, J. I.; Eales, S. A.; Galametz, M.; Gomez, H. L.; Lebouteiller, V.; Madden, S.; Mentuch, E.; Page, M. J.; Pohlen, M.; Remy, A.; Roussel, H.; Sauvage, M.; Smith, M. W. L.; Spinoglio, L.

    2012-05-01

    We present photometry of the nearby galaxy NGC 5128 (Centaurus A) observed with the Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) instruments on board the Herschel Space Observatory, at 70, 160, 250, 350 and 500 μm, as well as new CO J= 3-2 observations taken with the HARP-B instrument on the James Clerk Maxwell Telescope (JCMT). Using a single-component modified blackbody, we model the dust spectral energy distribution within the disc of the galaxy using all five Herschel wavebands and find dust temperatures of ˜30 K towards the centre of the disc and a smoothly decreasing trend to ˜20 K with increasing radius. We find a total dust mass of (1.59 ± 0.05) × 107 M⊙ and a total gas mass of (2.7 ± 0.2) × 109 M⊙. The average gas-to-dust mass ratio is 103 ± 8, but we find an interesting increase in this ratio to approximately 275 towards the centre of Cen A. We discuss several possible physical processes that may be causing this effect, including dust sputtering, jet entrainment and systematic variables such as the XCO factor. Dust sputtering by X-rays originating in the active galactic nucleus or the removal of dust by the jets is our most favoured explanation. a PACS values are divisive and SPIRE values are multiplicative. b These uncertainties are for the pixels at their native pixel scale, as listed in this table. c We have ignored the fact that the SPIRE calibration errors are correlated between all three bands and our total 7 per cent error comprises 5 per cent correlated error and 5 per cent uncorrelated error.

  12. Mass distribution of particulates measured by Giotto's Dust Impact Detection System (DIDSY) in the close encounter period

    NASA Technical Reports Server (NTRS)

    Zarnecki, J. C.; Mcdonnell, J. A. M.; Burton, W. M.; Alexander, W. M.; Hanner, M. S.

    1986-01-01

    The cumulative mass distribution of the comet Halley dust efflux in the close encounter period -300 to +300 sec was analyzed. Analysis of the cumulative mass distribution index (alpha) shows considerable short time scale variation. There is clear evidence from the flux rates of passage through at least one major dust enhancement (dust jet) just after closest approach and this is associated with a steepening of the alpha. Comparison with measurements from other sources, and with preencounter predictions, is also made.

  13. Effects of variable dust size, charge and mass on the characteristics of dust acoustic solitary waves in a magnetized dusty plasma

    NASA Astrophysics Data System (ADS)

    Shahmoradi, Niloufar; Dorranian, Davoud

    2014-06-01

    The effect of dust size, mass and charge distributions on the characteristics of nonlinear dust acoustic solitary waves (DASW) in a two-temperature ion dusty plasma has been studied analytically. The mass and electrical charge of dust particles are assumed to be proportional with their size. Plasma is embedded in an external magnetic field with variable direction. Using a reductive perturbation method, the Zakharov-Kuznetsov (ZK) equation is derived and its solitary answers are extracted. The coefficients of the nonlinear term of the ZK equation are affected strongly by the size of dust particles when the relative size (the ratio of the largest dust radius to smallest dust radius) is less than 2. Both the width and amplitude of DASW increase with increasing relative size. The cyclotron frequency of the dust changes with the relative size of the dust particles. DASW width is influenced by the magnitude as well as direction of the external magnetic field, while its amplitude is independent of the magnitude of the external magnetic field. At each strength of the external magnetic field, there is an optimum magnitude for its direction at which the width of DASW is maximum.

  14. Dust Production from Sub-Solar to Super-Solar Metallicity in Thermally Pulsing Asymptotic Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    Nanni, A.; Bressan, A.; Marigo, P.; Girardi, L.; Javadi, A.; van Loon, J. Th.

    2015-08-01

    We discuss the dust chemistry and growth in the circumstellar envelopes (CSEs) of Thermally Pulsing Asymptotic Giant Branch (TP-AGB) star models, computed with the COLIBRI code, at varying initial mass and metallicity (Z = 0.001, 0.008, 0.02, 0.04, 0.06). A relevant result of our analysis deals with silicate production in M stars. We show that, in order to reproduce the observed trend between terminal velocities and mass-loss rates in Galactic M giants, one has to significantly reduce the efficiency of chemisputtering by H2 molecules, usually considered the most effective dust destruction mechanism. This conclusion is in agreement with the most recent laboratory results, which show that silicates may condense already at Tcond˜1400 K, rather than only at Tcond˜1000 K, as obtained by models that include chemisputtering. From analysis of the total dust ejecta, we find that the dust-to-gas ratios of the total ejecta from intermediate-mass stars are much less dependent on metallicity than usually assumed. In a broader context, our results are suitable for studying the dust enrichment of the interstellar medium provided by TP-AGB stars in both nearby and high-redshift galaxies.

  15. Can Lightning Produce Significant Levels of Mass-Independent Oxygen Isotopic Fractionation in Nebular Dust?

    NASA Technical Reports Server (NTRS)

    Nuth, Joseph A.; Paquette, John A.; Farquhar, Adam

    2012-01-01

    Based on recent evidence that oxide grains condensed from a plasma will contain oxygen that is mass independently fractionated compared to the initial composition of the vapor, we present a first attempt to evaluate the potential magnitude of this effect on dust in the primitive solar nebula. This assessment relies on previous studies of nebular lightning to provide reasonable ranges of physical parameters to form a very simple model to evaluate the plausibility that lightning could affect a significant fraction of nebular dust and that such effects could cause a significant change in the oxygen isotopic composition of solids in the solar nebula over time. If only a small fraction of the accretion energy is dissipated as lightning over the volume of the inner solar nebula, then a large fraction of nebular dust will be exposed to lightning. If the temperature of such bolts is a few percent of the temperatures measured in terrestrial discharges, then dust will vaporize and recondense in an ionized environment. Finally, if only a small average decrease is assumed in the O-16 content of freshly condensed dust, then over the last 5 million years of nebular accretion the average delta O-17 of the dust could increase by more than 30 per mil. We conclude that it is possible that the measured " slope 1" oxygen isotope line measured in meteorites and their components represents a time-evolution sequence of nebular dust over the last several million years of nebular evolution O-16-rich materials formed first, then escaped further processing as the average isotopic composition of the dust graduaUy became increasingly depleted in O-16 .

  16. ALMA Survey of Lupus Protoplanetary Disks. I. Dust and Gas Masses

    NASA Astrophysics Data System (ADS)

    Ansdell, M.; Williams, J. P.; van der Marel, N.; Carpenter, J. M.; Guidi, G.; Hogerheijde, M.; Mathews, G. S.; Manara, C. F.; Miotello, A.; Natta, A.; Oliveira, I.; Tazzari, M.; Testi, L.; van Dishoeck, E. F.; van Terwisga, S. E.

    2016-09-01

    We present the first high-resolution sub-millimeter survey of both dust and gas for a large population of protoplanetary disks. Characterizing fundamental properties of protoplanetary disks on a statistical level is critical to understanding how disks evolve into the diverse exoplanet population. We use the Atacama Large Millimeter/Submillimeter Array (ALMA) to survey 89 protoplanetary disks around stars with {M}* \\gt 0.1 {M}ȯ in the young (1–3 Myr), nearby (150–200 pc) Lupus complex. Our observations cover the 890 μm continuum and the 13CO and C18O 3–2 lines. We use the sub-millimeter continuum to constrain {M}{{dust}} to a few Martian masses (0.2–0.4 M ⊕) and the CO isotopologue lines to constrain {M}{{gas}} to roughly a Jupiter mass (assuming an interstellar medium (ISM)-like [{CO}]/[{{{H}}}2] abundance). Of 89 sources, we detect 62 in continuum, 36 in 13CO, and 11 in C18O at \\gt 3σ significance. Stacking individually undetected sources limits their average dust mass to ≲ 6 Lunar masses (0.03 M ⊕), indicating rapid evolution once disk clearing begins. We find a positive correlation between {M}{{dust}} and M *, and present the first evidence for a positive correlation between {M}{{gas}} and M *, which may explain the dependence of giant planet frequency on host star mass. The mean dust mass in Lupus is 3× higher than in Upper Sco, while the dust mass distributions in Lupus and Taurus are statistically indistinguishable. Most detected disks have {M}{{gas}}≲ 1 {M}{{Jup}} and gas-to-dust ratios \\lt 100, assuming an ISM-like [{CO}]/[{{{H}}}2] abundance; unless CO is very depleted, the inferred gas depletion indicates that planet formation is well underway by a few Myr and may explain the unexpected prevalence of super-Earths in the exoplanet population.

  17. Computational prediction of dust production in graphite moderated pebble bed reactors

    NASA Astrophysics Data System (ADS)

    Rostamian, Maziar

    The scope of the work reported here, which is the computational study of graphite wear behavior, supports the Nuclear Engineering University Programs project "Experimental Study and Computational Simulations of Key Pebble Bed Thermomechanics Issues for Design and Safety" funded by the US Department of Energy. In this work, modeling and simulating the contact mechanics, as anticipated in a PBR configuration, is carried out for the purpose of assessing the amount of dust generated during a full power operation year of a PBR. A methodology that encompasses finite element analysis (FEA) and micromechanics of wear is developed to address the issue of dust production and its quantification. Particularly, the phenomenon of wear and change of its rate with sliding length is the main focus of this dissertation. This work studies the wear properties of graphite by simulating pebble motion and interactions of a specific type of nuclear grade graphite, IG-11. This study consists of two perspectives: macroscale stress analysis and microscale analysis of wear mechanisms. The first is a set of FEA simulations considering pebble-pebble frictional contact. In these simulations, the mass of generated graphite particulates due to frictional contact is calculated by incorporating FEA results into Archard's equation, which is a linear correlation between wear mass and wear length. However, the experimental data by Johnson, University of Idaho, revealed that the wear rate of graphite decreases with sliding length. This is because the surfaces of the graphite pebbles become smoother over time, which results in a gradual decrease in wear rate. In order to address the change in wear rate, a more detailed analysis of wear mechanisms at room temperature is presented. In this microscale study, the wear behavior of graphite at the asperity level is studied by simulating the contact between asperities of facing surfaces. By introducing the effect of asperity removal on wear rate, a nonlinear

  18. Dust Coagulation in the Vicinity of a Gap-opening Jupiter-mass Planet

    NASA Astrophysics Data System (ADS)

    Carballido, Augusto; Matthews, Lorin S.; Hyde, Truell W.

    2016-06-01

    We analyze the coagulation of dust in and around a gap opened by a Jupiter-mass planet. To this end, we carry out a high-resolution magnetohydrodynamic (MHD) simulation of the gap environment, which is turbulent due to the magnetorotational instability. From the MHD simulation, we obtain values of the gas velocities, densities, and turbulent stresses (a) close to the gap edge, (b) in one of the two gas streams that accrete onto the planet, (c) inside the low-density gap, and (d) outside the gap. The MHD values are then input into a Monte Carlo dust-coagulation algorithm which models grain sticking and compaction. We also introduce a simple implementation for bouncing, for comparison purposes. We consider two dust populations for each region: one whose initial size distribution is monodisperse, with monomer radius equal to 1 μm, and another one whose initial size distribution follows the Mathis–Rumpl–Nordsieck distribution for interstellar dust grains, with an initial range of monomer radii between 0.5 and 10 μm. Without bouncing, our Monte Carlo calculations show steady growth of dust aggregates in all regions, and the mass-weighted (m-w) average porosity of the initially monodisperse population reaches extremely high final values of 98%. The final m-w porosities in all other cases without bouncing range between 30% and 82%. The efficiency of compaction is due to high turbulent relative speeds between dust particles. When bouncing is introduced, growth is slowed down in the planetary wake and inside the gap. Future studies will need to explore the effect of different planet masses and electric charge on grains.

  19. Cometary and interstellar dust grains - Analysis by ion microprobe mass spectrometry and other techniques

    NASA Astrophysics Data System (ADS)

    Zinner, E.

    1991-04-01

    A survey of microanalytical measurements on interplanetary dust particles (IDPs) and interstellar dust grains from primitive meteorites is presented. Ion-microprobe mass spectrometry with its capability to determine isotopic compositions of many elements on a micron spatial scale has played a special role. Examples are measurements of H, N, and O isotopes and refractory trace elements in IDPs; C, N, Mg, and Si isotopes in interstellar SiC grains; and C and N isotopes and H, N, Al, and Si concentrations in interstellar graphite grains.

  20. Uptake of acetylene on cosmic dust and production of benzene in Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Frankland, Victoria L.; James, Alexander D.; Sánchez, Juan Diego Carrillo; Mangan, Thomas P.; Willacy, Karen; Poppe, Andrew R.; Plane, John M. C.

    2016-11-01

    A low-temperature flow tube and ultra-high vacuum apparatus were used to explore the uptake and heterogeneous chemistry of acetylene (C2H2) on cosmic dust analogues over the temperature range encountered in Titan's atmosphere below 600 km. The uptake coefficient, γ, was measured at 181 K to be (1.6 ± 0.4) × 10-4, (1.9 ± 0.4) × 10-4 and (1.5 ± 0.4) × 10-4 for the uptake of C2H2 on Mg2SiO4, MgFeSiO4 and Fe2SiO4, respectively, indicating that γ is independent of Mg or Fe active sites. The uptake of C2H2 was also measured on SiO2 and SiC as analogues for meteoric smoke particles in Titan's atmosphere, but was found to be below the detection limit (γ < 6 × 10-8 and < 4 × 10-7, respectively). The rate of cyclo-trimerization of C2H2 to C6H6 was found to be 2.6 × 10-5 exp(-741/T) s-1, with an uncertainty ranging from ± 27 % at 115 K to ± 49 % at 181 K. A chemical ablation model was used to show that the bulk of cosmic dust particles (radius 0.02-10 μm) entering Titan's atmosphere do not ablate (< 1% mass loss through sputtering), thereby providing a significant surface for heterogeneous chemistry. A 1D model of dust sedimentation shows that the production of C6H6via uptake of C2H2 on cosmic dust, followed by cyclo-trimerization and desorption, is probably competitive with gas-phase production of C6H6 between 80 and 120 km.

  1. The Evolution of Dust Mass in the Ejecta of SN1987A

    NASA Astrophysics Data System (ADS)

    Dwek, Eli; Arendt, Richard G.

    2015-09-01

    We present a new analysis of the infrared (IR) emission from the ejecta of SN 1987A covering days 615, 775, 1144, 8515, and 9090 after the explosion. We show that the observations are consistent with the rapid formation of about 0.4 {M}⊙ of dust, consisting of mostly silicates (MgSiO3), near day 615, and evolving to about 0.45 {M}⊙ of composite dust grains consisting of ˜0.4 {M}⊙ of silicates and ˜0.05 {M}⊙ of amorphous carbon after day ˜8500. The proposed scenario challenges previous claims that dust in supernova (SN) ejecta is predominantly carbon, and that it grew from an initial mass of ˜10-3 {M}⊙ , to over 0.5 {M}⊙ by cold accretion. It alleviates several problems with previous interpretations of the data: (1) it reconciles the abundances of silicon, magnesium, and carbon with the upper limits imposed by nucleosynthesis calculations, (2) it eliminates the requirement that most of the dust observed around day 9000 grew by cold accretion onto the ˜10-3 {M}⊙ of dust previously inferred for days 615 and 775 after the explosion, and (3) establishes the dominance of silicate over carbon dust in the SN ejecta. At early epochs, the IR luminosity of the dust is powered by the radioactive decay of 56Co, and at late times by at least (1.3-1.6) × 10-4 {M}⊙ of 44Ti.

  2. Dust in the Early Universe

    NASA Astrophysics Data System (ADS)

    Gall, Christa

    2012-07-01

    Dust grains are an essential component influencing the formation and evolution history of stars and galaxies in the early Universe. Large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift, where the epoch of cosmic evolution was only about 1 Gyr, bear witness to a rapid production of dust. However, the origin of these large dust masses remains unclear. Massive stars ending their lives as either asymptotic giant branch stars or supernovae have been contemplated as the prime sources of dust. Stars more massive than ~3 Msun are short-lived but whether their dust production efficiency is sufficient to account for the large dust masses is unknown. I shall address the challenge of reproducing current dust mass estimates arising from the strong sensitivity to the overall dust productivity of the sources involved, the initial mass function and star formation history. I will discuss the contribution of the stellar dust sources and alternatives, such as grain growth in the interstellar medium, to the dust budget in the high redshift as well as Local Group galaxies.

  3. Characteristics of tyre dust in polluted air: Studies by single particle mass spectrometry (ATOFMS)

    NASA Astrophysics Data System (ADS)

    Dall'Osto, Manuel; Beddows, David C. S.; Gietl, Johanna K.; Olatunbosun, Oluremi A.; Yang, Xiaoguang; Harrison, Roy M.

    2014-09-01

    There is a paucity of quantitative knowledge on the contributions of non-exhaust (abrasion and re-suspension) sources to traffic emissions. Abrasive emissions can be broadly categorised as tyre wear, brake wear and road dust/road surface wear. Current research often considers road dust and tyre dust as externally mixed particles, the former mainly composed of mineral matter and the latter solely composed of mainly organic matter and some trace elements. The aim of this work was to characterise tyre wear from both laboratory and field studies by using Aerosol Time-Of-Flight Mass Spectrometry (ATOFMS). Real-time single particle chemical composition was obtained from a set of rubber tyres rotating on a metal surface. Bimodal particle number size distributions peaking at 35 nm and 85 nm were obtained from SMPS/APS measurements over the range 6-20,000 nm. ATOFMS mass spectra of tyre wear in the particle size range 200-3000 nm diameter show peaks due to exo-sulphur compounds, nitrate, Zn and ions of high molecular weight (m/z > 100) attributed to organic polymers. Two large ATOFMS datasets collected from a number of outdoor studies were examined. The former was constituted of 48 road dust samples collected on the roads of London. The latter consisted of ATOFMS ambient air field studies from Europe, overall composed of more than 2,000,000 single particle mass spectra. The majority (95%) of tyre wear particles present in the road dust samples and atmospheric samples are internally mixed with metals (Li, Na, Ca, Fe, Ti), as well as phosphate. It is concluded that the interaction of tyres with the road surface creates particles internally mixed from two sources: tyre rubber and road surface materials. Measurements of the tyre rubber component alone may underestimate the contribution of tyre wear to concentrations of airborne particulate matter. The results presented are especially relevant for urban aerosol source apportionment and PM2.5 exposure assessment.

  4. Global dust sources detection using MODIS Deep Blue Collection 6 aerosol products

    NASA Astrophysics Data System (ADS)

    Pérez García-Pando, C.; Ginoux, P. A.

    2015-12-01

    Our understanding of the global dust cycle is limited by a dearth of information about dust sources, especially small-scale features which could account for a large fraction of global emissions. Remote sensing sensors are the most useful tool to locate dust sources. These sensors include microwaves, visible channels, and lidar. On the global scale, major dust source regions have been identified using polar orbiting satellite instruments. The MODIS Deep Blue algorithm has been particularly useful to detect small-scale sources such as floodplains, alluvial fans, rivers, and wadis , as well as to identify anthropogenic sources from agriculture. The recent release of Collection 6 MODIS aerosol products allows to extend dust source detection to the entire land surfaces, which is quite useful to identify mid to high latitude dust sources and detect not only dust from agriculture but fugitive dust from transport and industrial activities. This presentation will overview the advantages and drawbacks of using MODIS Deep Blue for dust detection, compare to other instruments (polar orbiting and geostationary). The results of Collection 6 with a new dust screening will be compared against AERONET. Applications to long range transport of anthropogenic dust will be presented.

  5. Gas and dust in the star-forming region ρ Oph A. The dust opacity exponent β and the gas-to-dust mass ratio g2d

    NASA Astrophysics Data System (ADS)

    Liseau, R.; Larsson, B.; Lunttila, T.; Olberg, M.; Rydbeck, G.; Bergman, P.; Justtanont, K.; Olofsson, G.; de Vries, B. L.

    2015-06-01

    Aims: We aim at determining the spatial distribution of the gas and dust in star-forming regions and address their relative abundances in quantitative terms. We also examine the dust opacity exponent β for spatial and/or temporal variations. Methods: Using mapping observations of the very dense ρ Oph A core, we examined standard 1D and non-standard 3D methods to analyse data of far-infrared and submillimetre (submm) continuum radiation. The resulting dust surface density distribution can be compared to that of the gas. The latter was derived from the analysis of accompanying molecular line emission, observed with Herschel from space and with APEX from the ground. As a gas tracer we used N2H+, which is believed to be much less sensitive to freeze-out than CO and its isotopologues. Radiative transfer modelling of the N2H+ (J = 3-2) and (J = 6-5) lines with their hyperfine structure explicitly taken into account provides solutions for the spatial distribution of the column density N(H2), hence the surface density distribution of the gas. Results: The gas-to-dust mass ratio is varying across the map, with very low values in the central regions around the core SM 1. The global average, = 88, is not far from the canonical value of 100, however. In ρ Oph A, the exponent β of the power-law description for the dust opacity exhibits a clear dependence on time, with high values of 2 for the envelope-dominated emission in starless Class -1 sources to low values close to 0 for the disk-dominated emission in Class III objects. β assumes intermediate values for evolutionary classes in between. Conclusions: Since β is primarily controlled by grain size, grain growth mostly occurs in circumstellar disks. The spatial segregation of gas and dust, seen in projection toward the core centre, probably implies that, like C18O, also N2H+ is frozen onto the grains. Based on observations with APEX, which is a 12 m diameter submillimetre telescope at 5100 m altitude on Llano Chajnantor

  6. DUST CONTINUUM EMISSION AS A TRACER OF GAS MASS IN GALAXIES

    SciTech Connect

    Groves, Brent A.; Schinnerer, Eva; Walter, Fabian; Leroy, Adam; Galametz, Maud; Bolatto, Alberto; Hunt, Leslie; Dale, Daniel; Calzetti, Daniela; Croxall, Kevin; Kennicutt, Robert Jr.

    2015-01-20

    We use a sample of 36 galaxies from the KINGFISH (Herschel IR), HERACLES (IRAM CO), and THINGS (Very Large Array H I) surveys to study empirical relations between Herschel infrared (IR) luminosities and the total mass of the interstellar gas (H{sub 2} + H I). Such a comparison provides a simple empirical relationship without introducing the uncertainty of dust model fitting. We find tight correlations, and provide fits to these relations, between Herschel luminosities and the total gas mass integrated over entire galaxies, with the tightest, almost linear, correlation found for the longest wavelength data (SPIRE 500). However, we find that accounting for the gas-phase metallicity (affecting the dust to gas ratio) is crucial when applying these relations to low-mass, and presumably high-redshift, galaxies. The molecular (H{sub 2}) gas mass is found to be better correlated with the peak of the IR emission (e.g., PACS160), driven mostly by the correlation of stellar mass and mean dust temperature. When examining these relations as a function of galactocentric radius, we find the same correlations, albeit with a larger scatter, up to a radius of r ∼ 0.7 r {sub 25} (containing most of a galaxy's baryonic mass). However, beyond that radius, the same correlations no longer hold, with increasing gas (predominantly H I) mass relative to the infrared emission. The tight relations found for the bulk of the galaxy's baryonic content suggest that total gas masses of disk-like (non-merging/ULIRG) galaxies can be inferred from far-infrared continuum measurements in situations where only the latter are available, e.g., in ALMA continuum observations of high-redshift galaxies.

  7. High correlations between Asian dust events and biological productivity in the western North Pacific

    NASA Astrophysics Data System (ADS)

    Yuan, Wei; Zhang, Jing

    2006-04-01

    The relationship between dust events at 11 meteorological stations in China and sediment-trap fluxes at KNOT (the Kyodo North Pacific Ocean Time-series station) was investigated during the period December 1997 to April 2000. Al flux, as a good proxy of continental dust, has significant correlations (0.66-0.78) with dust events at a water depth of 924 m. It suggests that the Badain Juran Desert region is a primary source of eolian dust to the western North Pacific. High correlations appeared between the dust events and opal flux, and PD (pennate diatoms) also. This suggests that dust events stimulate biological productivity, providing nutrients via processes such as particle floating, adsorption and co-precipitation. In addition, evident correlation existed between opal flux at 924 m and GHA (geopotential height anomalies) at 850 hPa level with about a 10-day time lag. Therefore, it suggests atmospheric cyclone activities might also contribute to ocean productivity.

  8. DUST PROPERTIES AND DISK STRUCTURE OF EVOLVED PROTOPLANETARY DISKS IN Cep OB2: GRAIN GROWTH, SETTLING, GAS AND DUST MASS, AND INSIDE-OUT EVOLUTION

    SciTech Connect

    Sicilia-Aguilar, Aurora; Henning, Thomas; Dullemond, Cornelis P.; Bouwman, Jeroen; Sturm, Bernhard; Patel, Nimesh; Juhasz, Attila E-mail: aurora.sicilia@uam.es

    2011-11-20

    We present Spitzer/Infrared Spectrograph spectra of 31 T Tauri stars (TTS) and IRAM/1.3 mm observations for 34 low- and intermediate-mass stars in the Cep OB2 region. Including our previously published data, we analyze 56 TTS and 3 intermediate-mass stars with silicate features in Tr 37 ({approx}4 Myr) and NGC 7160 ({approx}12 Myr). The silicate emission features are well reproduced with a mixture of amorphous (with olivine, forsterite, and silica stoichiometry) and crystalline grains (forsterite, enstatite). We explore grain size and disk structure using radiative transfer disk models, finding that most objects have suffered substantial evolution (grain growth, settling). About half of the disks show inside-out evolution, with either dust-cleared inner holes or a radially dependent dust distribution, typically with larger grains and more settling in the innermost disk. The typical strong silicate features nevertheless require the presence of small dust grains, and could be explained by differential settling according to grain size, anomalous dust distributions, and/or optically thin dust populations within disk gaps. M-type stars tend to have weaker silicate emission and steeper spectral energy distributions than K-type objects. The inferred low dust masses are in a strong contrast with the relatively high gas accretion rates, suggesting global grain growth and/or an anomalous gas-to-dust ratio. Transition disks in the Cep OB2 region display strongly processed grains, suggesting that they are dominated by dust evolution and settling. Finally, the presence of rare but remarkable disks with strong accretion at old ages reveals that some very massive disks may still survive to grain growth, gravitational instabilities, and planet formation.

  9. Measures of galaxy dust and gas mass with Herschel photometry and prospects for ALMA

    NASA Astrophysics Data System (ADS)

    Berta, S.; Lutz, D.; Genzel, R.; Förster-Schreiber, N. M.; Tacconi, L. J.

    2016-03-01

    Combining the deepest Herschel extragalactic surveys (PEP, GOODS-H, HerMES), and Monte Carlo mock catalogs, we explore the robustness of dust mass estimates based on modeling of broadband spectral energy distributions (SEDs) with two popular approaches: Draine & Li (2007, ApJ, 657, 810; DL07) and a modified blackbody (MBB). We analyze the cause, drivers, and trends of uncertainties and systematics in thorough detail. As long as the observed SED extends to at least 160-200 μm in the rest frame, Mdust can be recovered with a >3σ significance and without the occurrence of systematics. An average offset of a factor ~1.5 exists between DL07- and MBB-based dust masses, based on consistent dust properties. The performance of DL07 modeling turns out to be more robust than that of MBB since relative errors on Mdust are more mildly dependent on the maximum covered rest-frame wavelength and are less scattered. At the depth of the deepest Herschel surveys (in the GOODS-S field), it is possible to retrieve dust masses with a signal-to-noise ratio, S/N ≥ 3 for galaxies on the main sequence of star formation (MS) down to M∗ ~ 1010 [M⊙] up to z ~ 1. At higher redshift (z ≤ 2), the same result is only achieved for objects at the tip of the MS or for those objects lying above the tip owing to sensitivity and wavelength coverage limitations. Molecular gas masses, obtained by converting Mdust through the metallicity-dependent gas-to-dust ratio δGDR, are consistent with those based on the scaling of depletion time, τdep, and on CO sub-mm spectroscopy. Focusing on CO-detected galaxies at z> 1, the δGDR dependence on metallicity is consistent with the local relation, provided that a sufficient SED coverage is available. Once we established that Herschel-only and sub-mm-only estimates of dust masses can be affected by large uncertainties and possibly systematics in some cases, we combined far-IR Herschel data and sub-mm ALMA expected fluxes to study the advantages of a full

  10. A Stubbornly Large Mass of Cold Dust in the Ejecta of Supernova 1987A

    NASA Astrophysics Data System (ADS)

    Matsuura, M.; Dwek, E.; Barlow, M. J.; Babler, B.; Baes, M.; Meixner, M.; Cernicharo, José; Clayton, Geoff C.; Dunne, L.; Fransson, C.; Fritz, Jacopo; Gear, Walter; Gomez, H. L.; Groenewegen, M. A. T.; Indebetouw, R.; Ivison, R. J.; Jerkstrand, A.; Lebouteiller, V.; Lim, T. L.; Lundqvist, P.; Pearson, C. P.; Roman-Duval, J.; Royer, P.; Staveley-Smith, Lister; Swinyard, B. M.; van Hoof, P. A. M.; van Loon, J. Th.; Verstappen, Joris; Wesson, Roger; Zanardo, Giovanna; Blommaert, Joris A. D. L.; Decin, Leen; Reach, W. T.; Sonneborn, George; Van de Steene, Griet C.; Yates, Jeremy A.

    2015-02-01

    We present new Herschel photometric and spectroscopic observations of Supernova 1987A, carried out in 2012. Our dedicated photometric measurements provide new 70 μm data and improved imaging quality at 100 and 160 μm compared to previous observations in 2010. Our Herschel spectra show only weak CO line emission, and provide an upper limit for the 63 μm [O I] line flux, eliminating the possibility that line contaminations distort the previously estimated dust mass. The far-infrared spectral energy distribution (SED) is well fitted by thermal emission from cold dust. The newly measured 70 μm flux constrains the dust temperature, limiting it to nearly a single temperature. The far-infrared emission can be fitted by 0.5 ± 0.1 M ⊙ of amorphous carbon, about a factor of two larger than the current nucleosynthetic mass prediction for carbon. The observation of SiO molecules at early and late phases suggests that silicates may also have formed and we could fit the SED with a combination of 0.3 M ⊙ of amorphous carbon and 0.5 M ⊙ of silicates, totalling 0.8 M ⊙ of dust. Our analysis thus supports the presence of a large dust reservoir in the ejecta of SN 1987A. The inferred dust mass suggests that supernovae can be an important source of dust in the interstellar medium, from local to high-redshift galaxies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. PACS has been developed by a consortium of institutes led by MPE (Germany) and including UVIE (Austria); KU Leuven, CSL, IMEC (Belgium); CEA, LAM (France); MPIA (Germany); INAF-IFSI/OAA/OAP/OAT, LENS, SISSA (Italy); IAC (Spain). This development has been supported by the funding agencies BMVIT (Austria), ESA-PRODEX (Belgium), CEA/CNES (France), DLR (Germany), ASI/INAF (Italy), and CICYT/MCYT (Spain). SPIRE has been developed by a consortium of institutes led by Cardiff University (UK) and

  11. Mass loss and dust formation around oxygen-rich evolved stars

    NASA Astrophysics Data System (ADS)

    Kemper, F.

    2002-09-01

    This work is a study of the formation of dust around oxygen-rich evolved stars, in correlation with the physical conditions in this environment. ISO SWS and LWS spectroscopy has been analysed, and several mineral and molecular species are identified. For two evolved stars: OH/IR star OH 127.8+0.0 and planetary nebula NGC 6302, the spectral energy distribution has been fitted. Metallic iron and carbonates are identified as new dust components. In addition, the degree of crystallinity of silicates has been studied as a function of mass-loss rate. Finally, submm observations of rotational transitions of CO have been analysed to study the mass-loss history of oxygen-rich AGB stars.

  12. Capabilities and Limitations of MISR Aerosol Products in Dust-Laden Regions

    NASA Technical Reports Server (NTRS)

    Kalashnikova, Olga V.; Garay, Michael J.; Sokolik, Irina N.; Diner, David J.; Kahn, Ralph A.; Martonchcik, John V.; Lee, Jae N.; Torres, Omar; Yang, Weidong; Marshak, Alexander; Kassabian, Sero; Chodas, Mark

    2011-01-01

    Atmospheric mineral dust particles have significant effects on climate and the environment, and despite notable advances in modeling and satellite and ground-based measurements, remain one of the major factors contributing to large uncertainty in aerosol radiative forcing. We examine the Multi-angle Imaging SpectroRadiometer (MISR) 11+ year aerosol data record to demonstrate MISR's unique strengths and assess potential biases of MISR products for dust study applications. In particular, we examine MISR's unique capabilities to 1) distinguish dust aerosol from spherical aerosol types, 2) provide aerosol optical depths over bright desert source regions, and 3) provide high-resolution retrievals of dust plume heights and associated winds. We show examples of regional and global MISR data products in dusty regions together with quantitative evaluations of product accuracies through comparisons with independent data sources, and demonstrate applications of MISR data to dust regional and climatological studies, such as dust property evolution during transport, dust source climatology in relation to climatic factors, and dust source dynamics. The potential use of MISR radiance data to study dust properties is also discussed.

  13. The role of dust in mass loss from late-type stars

    NASA Technical Reports Server (NTRS)

    Jura, M.

    1986-01-01

    It is noted that, in almost all late-type stars with measured mass loss rates, there is sufficient momentum in the radiation to dominate the dynamics. The opacity of the material is sufficiently great to render radiation pressure important; the dust forms close enough to the central star for radiation pressure to account for the observed outflow velocities. Pulsations appear to be important in raising the material far enough above the photosphere for grains to condense.

  14. Monitoring requested for developing planetary systems dust production study

    NASA Astrophysics Data System (ADS)

    Waagen, Elizabeth O.

    2015-03-01

    Dr. George Rieke (University of Arizona) and colleagues have requested AAVSO assistance in monitoring four stars with developing planetary systems: RZ Psc, HD 15407A, V488 Per, and HD 23514. This campaign is similar to the one conducted in 2013 (see AAVSO Alert Notice 482). Dr. Rieke writes: "We have obtained 130 hours of time on the Spitzer Space Telescope to continue monitoring planetary debris disks for variability. We are asking for help from AAVSO for this program. Debris disks [are] systems of dust and particles associated with planetary systems...There are about a dozen planetary systems in which there is evidence that massive collisions are occurring right now, collisions that are building planets in much the same way that a large body added most of its mass to that of the Earth and created the Moon as a byproduct when the Solar System was young...A key part of our program is to obtain optical photometry of the same stars that we are observing in the infrared under the Spitzer program. The optical data are needed to verify that any changes we see in the infrared are not just driven by changes in the brightness of the star, but are truly due to changes in the structure or dust content of the debris disk. AAVSO observers provided this support for our previous program, as summarized in a paper [in preparation]; all of those who contributed data are co-authors of the paper. We request AAVSO to take similar observations for the new program...", which begins immediately and runs in two segments, now through May and September through December [target information and satellite schedule in full Alert Notice 511]. Observations in V are requested, with a S/N of about 100 so that the accuracy will be 1-2%. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for schedule and other details.

  15. Characteristics of dusts encountered during the production of cemented tungsten carbides.

    PubMed

    Stefaniak, Aleksandr B; Day, Gregory A; Harvey, Christopher J; Leonard, Stephen S; Schwegler-Berry, Diane E; Chipera, Steve J; Sahakian, Nancy M; Chisholm, William P

    2007-12-01

    Inhalation of cobalt (Co) and tungsten carbide (WC) particles, but not Co or WC alone, may cause hard metal disease, risk of which does not appear to be uniform across cemented tungsten carbide (CTC) production processes. Inhalation of Co alone or in the presence of WC may cause asthma. Hypothesizing that aerosol size, chemical content, heterogeneity, and constituent compaction may be important exposure factors, we characterized aerosols from representative CTC manufacturing processes. Six work areas were sampled to characterize aerosol size distributions (dust, Co) and 12 work areas were sampled to characterize physicochemical properties (using scanning electron microscopy with energy dispersive x-ray spectrometry [SEM-EDX]). Bulk feedstock and process-generated powders were characterized with SEM-EDX and x-ray diffraction. The dust mass median diameter was respirable and the cobalt respirable mass fraction was highest (37%) in grinding. Morphology of particles changed with processing: individual, agglomerate, or aggregates (pre-sintered materials), then mostly compacted particles (subsequent to sintering). Elemental composition of particles became increasingly heterogeneous: mostly discrete Co or W particles (prior to spray drying), then heterogeneous W/Co particles (subsequent work areas). Variability in aerosol respirability and chemical heterogeneity could translate into differences in toxicity and support detailed characterization of physicochemical properties during exposure assessments. PMID:18212475

  16. Evolved stars in the Local Group galaxies - I. AGB evolution and dust production in IC 1613

    NASA Astrophysics Data System (ADS)

    Dell'Agli, F.; Di Criscienzo, M.; Boyer, M. L.; García-Hernández, D. A.

    2016-08-01

    We used models of thermally-pulsing asymptotic giant branch (AGB) stars, that also describe the dust-formation process in the wind, to interpret the combination of near- and mid-infrared photometric data of the dwarf galaxy IC 1613. This is the first time that this approach is extended to an environment different from the Milky Way and the Magellanic Clouds (MCs). Our analysis, based on synthetic population techniques, shows a nice agreement between the observations and the expected distribution of stars in the colour-magnitude diagrams obtained with JHK and Spitzer bands. This allows a characterization of the individual stars in the AGB sample in terms of mass, chemical composition, and formation epoch of the progenitors. We identify the stars exhibiting the largest degree of obscuration as carbon stars evolving through the final AGB phases, descending from 1-1.25Msun objects of metallicity Z=0.001 and from 1.5-2.5Msun stars with Z=0.002. Oxygen-rich stars constitute the majority of the sample (65%), mainly low mass stars (<2Msun) that produce a negligible amount of dust (<10^{-7}Msun/yr). We predict the overall dust-production rate from IC 1613, mostly determined by carbon stars, to be 6x10^{-7}Msun/yr with an uncertainty of 30%. The capability of the current generation of models to interpret the AGB population in an environment different from the MCs opens the possibility to extend this kind of analysis to other Local Group galaxies.

  17. Evolved stars in the Local Group galaxies. I. AGB evolution and dust production in IC 1613

    NASA Astrophysics Data System (ADS)

    Dell'Agli, F.; Di Criscienzo, M.; Boyer, M. L.; García-Hernández, D. A.

    2016-05-01

    We used models of thermally-pulsing asymptotic giant branch (AGB) stars, that also describe the dust-formation process in the wind, to interpret the combination of near- and mid-infrared photometric data of the dwarf galaxy IC 1613. This is the first time that this approach is extended to an environment different from the Milky Way and the Magellanic Clouds (MCs). Our analysis, based on synthetic population techniques, shows a nice agreement between the observations and the expected distribution of stars in the colour-magnitude diagrams obtained with JHK and Spitzer bands. This allows a characterization of the individual stars in the AGB sample in terms of mass, chemical composition, and formation epoch of the progenitors. We identify the stars exhibiting the largest degree of obscuration as carbon stars evolving through the final AGB phases, descending from 1 - 1.25M⊙ objects of metallicity Z = 10-3 and from 1.5 - 2.5M⊙ stars with Z = 2 × 10-3. Oxygen-rich stars constitute the majority of the sample (˜65%), mainly low mass stars (<2M⊙) that produce a negligible amount of dust (≤10-7M⊙/yr). We predict the overall dust-production rate from IC 1613, mostly determined by carbon stars, to be ˜6 × 10-7M⊙/yr with an uncertainty of 30%. The capability of the current generation of models to interpret the AGB population in an environment different from the MCs opens the possibility to extend this kind of analysis to other Local Group galaxies.

  18. Evolved stars in the Local Group galaxies - I. AGB evolution and dust production in IC 1613

    NASA Astrophysics Data System (ADS)

    Dell'Agli, F.; Di Criscienzo, M.; Boyer, M. L.; García-Hernández, D. A.

    2016-08-01

    We used models of thermally pulsing asymptotic giant branch (AGB) stars, which also describe the dust-formation process in the wind, to interpret the combination of near- and mid-infrared photometric data of the dwarf galaxy IC 1613. This is the first time that this approach is extended to an environment different from the Milky Way and the Magellanic Clouds (MCs). Our analysis, based on synthetic population techniques, shows nice agreement between the observations and the expected distribution of stars in the colour-magnitude diagrams obtained with JHK and Spitzer bands. This allows a characterization of the individual stars in the AGB sample in terms of mass, chemical composition and formation epoch of the progenitors. We identify the stars exhibiting the largest degree of obscuration as carbon stars evolving through the final AGB phases, descending from 1-1.25 M⊙ objects of metallicity Z = 10-3 and from 1.5-2.5 M⊙ stars with Z = 2 × 10-3. Oxygen-rich stars constitute the majority of the sample (˜65 per cent), mainly low-mass stars (<2 M⊙) that produce a negligible amount of dust (≤10-7 M⊙ yr-1). We predict the overall dust-production rate from IC 1613, mostly determined by carbon stars, to be ˜6 × 10-7 M⊙ yr-1 with an uncertainty of 30 per cent. The capability of the current generation of models to interpret the AGB population in an environment different from the MCs opens the possibility to extend this kind of analysis to other Local Group galaxies.

  19. Influence of mineral dust surface chemistry on eicosanoid production by the alveolar macrophage.

    PubMed

    Kuhn, D C; Demers, L M

    1992-01-01

    It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology that results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoids) have been implicated as important biochemical mediators of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dust could influence the production of proinflammatory mediators in the lung environment. Primary cultures of rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500 and 1100 degrees C. Prostaglandin E2 (PGE2), thromboxane A2 (TXA2), and leukotriene B4 (LTB4) levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 production was markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE2 production. Exposure of AM to freshly fractured coal dust resulted in a significant increase in production by AM, while exposure to stale coal dust did not influence AM TXA2 production. Neither "fresh" nor "stale" coal dust had any effect on LTB4 production. In vitro exposure of AM to untreated silica resulted in a significant increase in TXA2 PGE2, TXA2, and LTB4 production compared with control. However, exposure of AM to silica calcined to 1100 degrees C resulted in eicosanoid levels that were not significantly different from control. These effects were still apparent 8 wk after calcination of the silica particles. Silica was a more potent activator of AM eicosanoid production than was coal, and amorphous fumed silica was a more potent

  20. Improving the Pan-STARRs/2MASS 3-D dust map: Regularization for increased resolution and fidelity.

    NASA Astrophysics Data System (ADS)

    Finkbeiner, Douglas P.; Green, Gregory; Lee, Albert; Ford Schlafly, Edward

    2016-01-01

    The Green et al. (2015) 3-D map of interstellar dust uses photometry of nearly 1 billion stars from Pan-STARRS1 and 2MASS to infer the distribution of dust in the Milky Way. The current map treats each angular pixel (~ 6 arcmin) independently, and estimates the dust in 30 distance bins. However, dust structures cut across pixels and the fit could be improved by coupling the dust density in neighboring pixels. This also has the advantage that fewer stars would be required per pixel, allowing finer angular resolution. We propose a simple way to do this, and show that it allows the use of smaller angular pixels and produces sharper resolution in the distance direction for a test case in Orion. We intend to incorporate similar regularization into the next full-sky 3-D dust map.

  1. Applications of single-layered graphene sheets as mass sensors and atomistic dust detectors

    NASA Astrophysics Data System (ADS)

    Sakhaee-Pour, A.; Ahmadian, M. T.; Vafai, A.

    2008-01-01

    Molecular structural mechanics is implemented to model the vibrational behavior of defect-free single-layered graphene sheets (SLGSs) at constant temperature. To mimic these two-dimensional layers, zigzag and armchair models with cantilever and bridge boundary conditions are adopted. Fundamental frequencies of these nanostructures are calculated, and it is perceived that they are independent of the chirality and aspect ratio. The effects of point mass and atomistic dust on the fundamental frequencies are also considered in order to investigate the possibility of using SLGSs as sensors. The results show that the principal frequencies are highly sensitive to an added mass of the order of 10-6 fg.

  2. Potential of laser mass spectrometry for the analysis of environmental dust particles--a review.

    PubMed

    Aubriet, Frédéric; Carré, Vincent

    2010-02-01

    Laser-based aerosol mass spectrometry in both on-line and off-line modes has become an essential tool to analyze airborne and industrial dust particles. The versatility of laser desorption and/or ionization appears to be a powerful tool to obtain the global composition of environment particles. Laser mass spectrometry to analyze inorganic (elemental and molecular), organic and biological aerosol components without or with a restricted number of preparation steps in both on-line and off-line modes can be regarded as an ideal analytical machine. However, some limitations are associated to this range of mass spectrometry techniques. This review presents the fundamental aspects of laser-based mass spectrometry and the different kinds of analyses, which may be done. A selected number of applications are then given which allows the reader to consider both the capabilities and the drawbacks of laser mass spectrometry to analyze dust environmental particles. Critical discussion is focused on comparison and new trends of these aerosol analytical techniques. PMID:20103104

  3. Neutral Mass Spectrometer (NMS) for the Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Mahaffy, Paul R.; Benna, Mehdi; King, Todd T.; Hodges, Richard

    2011-01-01

    The Lunar Atmosphere and Dust Environment Explorer (LADEE) mission currently scheduled for launch in early 2013 aboard a Minotaur V will orbit the moon at a nominal periselene of 50 km to characterized the lunar atmosphere and dust environment. The science instrument payload includes a neutral mass spectrometer as well as an ultraviolet spectrometer and a dust detector. Although to date only He, Ar-40, K, Na and Rn-222 have been firmly identified in the lunar exosphere and arise from the solar wind (He), the lunar regolith (K and Na) and the lunar interior (Ar-40, Rn-222), upper limits have been set for a large number of other species, LADEE Neutral Mass Spectrometer (NMS) observations will determine the abundance of several species and substantially lower the present upper limits for many others. Additionally, LADEE NMS will observe the spatial distribution and temporal variability of species which condense at nighttime and show peak concentrations at the dawn terminator (e,g, Ar-40), possible episodic release from the lunar interior, and the results of sputtering or desorption processes from the regolith. In this presentation, we describe the LADEE NMS hardware and the anticipated science results.

  4. Dust production in the galaxy: The meteorite perspective

    NASA Astrophysics Data System (ADS)

    O'D. Alexander, C. M.

    1997-03-01

    Five types of presolar grain have been isolated from meteorites-SiC, Si3N4, graphite, refractory oxides (Al2O3 and MgAl2O4), and nanodiamonds. With the exception of the nanodiamonds, single grains from each of the grain types have been isotopically analyzed. From the range of single grain isotopic compositions, a minimum of 35-40 stellar sources (AGB stars, supernovae and, possibly, novae and WR stars) are required. The relative galactic production rates of SiC, Si3N4, graphite, refractory oxide, and nanodiamond dust recorded by the presolar grains is compared with production rates estimated astronomically. The observed and estimated proportions of SiC from the various stellar sources agree quite well. Relative to the SiC grains, the abundance of supernova graphite grains is also close to astronomical estimates. However, AGB graphite/amorphous carbon, which should dominate, is highly depleted in meteorites. The AGB material may have been destroyed in the ISM or Solar System, but it is possible that the nanodiamonds, which are present in about the right abundance, are the missing carbonaceous material from AGB stars. The refractory presolar oxides are also underabundant compared to the SiC, but, as expected from astronomical data, they are dominated by grains from AGB stars. The oxide underabundance relative to SiC may be due to Al condensing in other phases that have yet to be found and/or because the oxides have a finer grain size distribution than the SiC. Similar reasons may also explain the underabundance of supernova oxide grains compared to AGB ones.

  5. Numerical Simulation of Aluminum Dust Detonations with Different Product Phases

    NASA Astrophysics Data System (ADS)

    Teng, H. H.; Jiang, Z. L.

    Detonation waves are waves of supersonic combustion induced by strong coupling shock and heat release. Detonation research has attracted much attention in recent years owing to its potential applications in hypersonic propulsion. Aluminum (Al) particle detonation is a type of dust detonation, and its research is important in the prevention of industrial explosions. Al dust detonations for flake and spherical particles have been studied , which is found to be very sensitive to the specific area[1].

  6. Analysis and differentiation of mineral dust by single particle laser mass spectrometry

    SciTech Connect

    Gallavardin, S. J.; Lohmann, U.; Cziczo, Daniel J.

    2008-05-09

    Abstract This study evaluates the potential of single particle laser desorption/ionization mass spectrometry for the analysis of atmospherically relevant mineral dusts. Samples of hematite, goethite, calcium carbonate, calcium sulfate, silica, quartz, montmorrillonite, kaolinite, illite, hectorite, wollastonite and nephelinsyenit were investigated in positive and negative ion mode with a monopolar time-of-flight mass spectrometer where the desorption/ionization step was performed with a 193 nm excimer laser (~109 W/cm2). Particle size ranged from 500 nm to 3 μm. Positive mass spectra mainly provide elemental composition whereas negative ion spectra provide information on element speciation and of a structural nature. The iron oxide, calcium-rich and aluminosilicate nature of particles is established in positive ion mode. The differentiation of calcium materials strongly relies on the calcium counter-ions in negative mass spectra. Aluminosilicates can be differentiated in both positive and negative ion mode using the relative abundance of various aluminum and silicon ions.

  7. Dust Masses of Disks around 8 Brown Dwarfs and Very Low-mass Stars in Upper Sco OB1 and Ophiuchus

    NASA Astrophysics Data System (ADS)

    van der Plas, G.; Ménard, F.; Ward-Duong, K.; Bulger, J.; Harvey, P. M.; Pinte, C.; Patience, J.; Hales, A.; Casassus, S.

    2016-03-01

    We present the results of ALMA band 7 observations of dust and CO gas in the disks around 7 objects with spectral types ranging between M5.5 and M7.5 in Upper Scorpius OB1, and one M3 star in Ophiuchus. We detect unresolved continuum emission in all but one source, and the 12CO J = 3 - 2 line in two sources. We constrain the dust and gas content of these systems using a grid of models calculated with the radiative transfer code MCFOST, and find disk dust masses between 0.1 and 1 M⊕, suggesting that the stellar mass/disk mass correlation can be extrapolated for brown dwarfs (BDs) with masses as low as 0.05 M⊙. The one disk in Upper Sco in which we detect CO emission, 2MASS J15555600, is also the disk with the warmest inner disk, as traced by its H-[4.5] photometric color. Using our radiative transfer grid, we extend the correlation between stellar luminosity and mass-averaged disk dust temperature, originally derived for stellar mass objects, to the BD regime to < {T}{dust}> ≈ 22{({L}*/{L}⊙ )}0.16 {{K}}, applicable to spectral types of M5 and later. This is slightly shallower than the relation for earlier spectral type objects and yields warmer low-mass disks. The two prescriptions cross at 0.27 L⊙, corresponding to masses between 0.1 and 0.2 M⊙ depending on age.

  8. The Neutral Mass Spectrometer on the Lunar Atmosphere and Dust Environment Explorer Mission

    NASA Astrophysics Data System (ADS)

    Mahaffy, Paul R.; Richard Hodges, R.; Benna, Mehdi; King, Todd; Arvey, Robert; Barciniak, Michael; Bendt, Mirl; Carigan, Daniel; Errigo, Therese; Harpold, Daniel N.; Holmes, Vincent; Johnson, Christopher S.; Kellogg, James; Kimvilakani, Patrick; Lefavor, Matthew; Hengemihle, Jerome; Jaeger, Ferzan; Lyness, Eric; Maurer, John; Nguyen, Daniel; Nolan, Thomas J.; Noreiga, Felix; Noriega, Marvin; Patel, Kiran; Prats, Benito; Quinones, Omar; Raaen, Eric; Tan, Florence; Weidner, Edwin; Woronowicz, Michael; Gundersen, Cynthia; Battel, Steven; Block, Bruce P.; Arnett, Ken; Miller, Ryan; Cooper, Curt; Edmonson, Charles

    2014-12-01

    The Neutral Mass Spectrometer (NMS) of the Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission is designed to measure the composition and variability of the tenuous lunar atmosphere. The NMS complements two other instruments on the LADEE spacecraft designed to secure spectroscopic measurements of lunar composition and in situ measurement of lunar dust over the course of a 100-day mission in order to sample multiple lunation periods. The NMS utilizes a dual ion source designed to measure both surface reactive and inert species and a quadrupole analyzer. The NMS is expected to secure time resolved measurements of helium and argon and determine abundance or upper limits for many other species either sputtered or thermally evolved from the lunar surface.

  9. The Neutral Mass Spectrometer on the Lunar Atmosphere and Dust Environment Explorer Mission

    NASA Technical Reports Server (NTRS)

    Mahaffy, Paul R.; Hodges, R. Richard; Benna, Mehdi; King, Todd; Arvey, Robert; Barciniak, Michael; Bendt, Mirl; Carigan, Daniel; Errigo, Therese; Harpold, Daniel N.; Holmes, Vincent; Johnson, Christopher S.; Kellogg, James; Kimvilakani, Patrick; Lefavor, Matthew; Hengemihle, Jerome; Jaeger, Ferzan; Lyness, Eric; Maurer, John; Nguyen, Daniel; Nolan, Thomas; Noreiga, Felix; Noreiga, Marvin; Patel, Kiran; Prats, Benito; Quinones, Omar; Raaen, Eric; Tan, Florence; Weidner, Edwin; Woronowicz, Michael; Gundersen, Cynthia (Inventor); Battel, Steven; Block, Bruce P.; Arnett, Ken; Miller, Ryan

    2014-01-01

    The Neutral Mass Spectrometer (NMS) of the Lunar Atmosphere and Dust Environment Explorer (LADEE) Mission is designed to measure the composition and variability of the tenuous lunar atmosphere. The NMS complements two other instruments on the LADEE spacecraft designed to secure spectroscopic measurements of lunar composition and in situ measurement of lunar dust over the course of a 100-day mission in order to sample multiple lunation periods. The NMS utilizes a dual ion source designed to measure both surface reactive and inert species and a quadrupole analyzer. The NMS is expected to secure time resolved measurements of helium and argon and determine abundance or upper limits for many other species either sputtered or thermally evolved from the lunar surface.

  10. Mass-spectrometric Measurements of Dust at Comets Wild-2 and Tempel-1

    NASA Astrophysics Data System (ADS)

    Kissel, J.; Mäkinen, T.; Schmidt, W.; Silén, J.

    2011-10-01

    Stardust and Stardust-NExT have successfully completed missions where two comets have been observed and one of them has been visited by two different spacecrafts. We discuss the observations made at the comets by the impact time of flight mass spectrometer CIDA [1]. At Wild-2, 29 spectra in positive and 2 in negative mode were observed [2]. At Tempel-1 CIDA recorded 46 spectra in negative mode on the inbound and 34 in positive mode on the outbound leg. The difference in speed for the two encounters makes the instrument observe different aspects of the physical and chemical properties of the dust grains. A taxonometry of the data is established using principal component analysis. The data from the two encounters is compared with data from the cruise phase where measurements of interplanetary dust were made.

  11. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years.

    PubMed

    Winckler, Gisela; Anderson, Robert F; Jaccard, Samuel L; Marcantonio, Franco

    2016-05-31

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity. PMID:27185933

  12. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years

    NASA Astrophysics Data System (ADS)

    Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Marcantonio, Franco

    2016-05-01

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity.

  13. Modelling supernova line profile asymmetries to determine ejecta dust masses: SN 1987A from days 714 to 3604

    NASA Astrophysics Data System (ADS)

    Bevan, Antonia; Barlow, M. J.

    2016-02-01

    The late-time optical and near-IR line profiles of many core-collapse supernovae exhibit a red-blue asymmetry as a result of greater extinction by internal dust of radiation emitted from the receding parts of the supernova ejecta. We present here a new code, DAMOCLES, that models the effects of dust on the line profiles of core-collapse supernovae in order to determine newly formed dust masses. We find that late-time dust-affected line profiles may exhibit an extended red scattering wing (as noted by Lucy et al. 1989) and that they need not be flux-biased towards the blue, although the profile peak will always be blueshifted. We have collated optical spectra of SN 1987A from a variety of archival sources and have modelled the Hα line from days 714 to 3604 and the [O I] 6300,6363 Å doublet between days 714 and 1478. Our line profile fits rule out day 714 dust masses >3 × 10-3 M⊙ for all grain types apart from pure magnesium silicates, for which no more than 0.07 M⊙ can be accommodated. Large grain radii ( ≥ 0.6 μm) are generally required to fit the line profiles even at the earlier epochs. We find that a large dust mass (≥0.1 M⊙) had formed by day 3604 and infer that the majority of the present dust mass must have formed after this epoch. Our findings agree with recent estimates from spectral energy distribution fits for the dust mass evolution of SN 1987A and support the inference that the majority of SN 1987A's dust formed many years after the initial explosion.

  14. Covariance between Star Formation Rates and Dust Mass of KINGFISH Galaxies

    NASA Astrophysics Data System (ADS)

    Rojas Bolivar, Randall; Calzetti, Daniela; Dale, Daniel A.; Cook, David

    2016-01-01

    We present the initial results for a study of the potential covariance between galaxy physical parameters (e.g., the star formation rate and dust mass) derived from the infrared spectral energy distributions (SEDs) of galaxies. With the emergence of powerful facilities and instruments in the millimeter and sub-millimeter wavelengths, which complement data from infrared space telescopes like Herschel, scientists have been able to observe the infrared SEDs of faraway galaxies (with redshifts between 2 and 5). These SEDs are being used to derive both star formation rates (SFR) and dust masses, the latter related to gas masses. The relationship between SFRs and gas masses determine the fundamental scaling laws of star formation (the Schmidt Kennicutt Law). Thus, it is fundamental to ascertain whether derivation of these quantities from IR SEDs may be affected by covariance. We will use the Spitzer and Herschel data from the nearby survey: Key Insights on Nearby Galaxies: A Far-IR Survey with Herschel (KINGFISH), which includes 61 nearby galaxies observed between 3.6 and 500 micron.

  15. ON THE INITIAL MASS FUNCTION OF LOW-METALLICITY STARS: THE IMPORTANCE OF DUST COOLING

    SciTech Connect

    Dopcke, Gustavo; Glover, Simon C. O.; Clark, Paul C.; Klessen, Ralf S.

    2013-04-01

    The first stars to form in the universe are believed to have distribution of masses biased toward massive stars. This contrasts with the present-day initial mass function, which has a predominance of stars with masses lower than 1 M{sub Sun }. Therefore, the mode of star formation must have changed as the universe evolved. Such a transition is attributed to a more efficient cooling provided by increasing metallicity. Especially dust cooling can overcome the compressional heating, which lowers the gas temperature thus increasing its instability to fragmentation. The purpose of this paper is to verify if dust cooling can efficiently cool the gas, and enhance the fragmentation of gas clouds at the early stages of the universe. To confirm that, we calculate a set of hydrodynamic simulations that include sink particles, which represent contracting protostars. The thermal evolution of the gas during the collapse is followed by making use of a primordial chemical network and also a recipe for dust cooling. We model four clouds with different amounts of metals (10{sup -4}, 10{sup -5}, 10-6 Z{sub Sun }, and 0), and analyze how this property affect the fragmentation of star-forming clouds. We find evidence for fragmentation in all four cases, and hence conclude that there is no critical metallicity below which fragmentation is impossible. Nevertheless, there is a clear change in the behavior of the clouds at Z {approx}< 10{sup -5} Z{sub Sun }, caused by the fact that at this metallicity, fragmentation takes longer to occur than accretion, leading to a flat mass function at lower metallicities.

  16. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: MIDWEST INDUSTRIAL SUPPLY, INC.'S EK35

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  17. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: MIDWEST INDUSTRIAL SUPPLY, INC.'S ENVIROKLEEN

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  18. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT: DUST SUPPRESSANT PRODUCTS: NORTH AMERICAN SALT COMPANY'S DUSTGARD

    EPA Science Inventory

    Dust suppressant products used to control particulate emissions from unpaved roads are among the technologies evaluated by the Air Pollution Control Technology (APCT) Verification Center, part of the U.S. Environmental Protection Agency's Environmental Technology Verification (ET...

  19. Calibration of the Neutral Mass Spectrometer for the Lunar Atmosphere and Dust Environment Explorer

    NASA Technical Reports Server (NTRS)

    Mahaffy, P. R.; Hodges, R. R.; Harpold, D. N.; King, T. T.; Jaeger, F.; Raaen, E.; Lyness, E.; Collier, M.; Benna, M.

    2012-01-01

    Science objectives of the LADEE Mission are to (1) determine the composition, and time variability of the tenuous lunar atmosphere and (2) to characterize the dust environment and its variability. These studies will extend the in-situ characterization of the environment that were carried out decades ago with the Apollo missions and a variety of ground based studies. The focused LADEE measurements will enable a more complete understanding of dust and gas sources and sinks. Sources of gas include UV photo-stimulated desorption, sputtering by plasma and micrometeorites, as well as thermal release of species such as argon from the cold service or venting from the lunar interior. Sinks include recondensation on the surface and escape through a variety of mechanisms. The LADEE science payload consists of an Ultraviolet Spectrometer, a Neutral Mass Spectrometer, and a Dust Detector. The LADEE orbit will include multiple passes at or below 50 km altitude and will target repeated sampling at the sunrise terminator where exospheric density will be highest for some thermally released species. The science mission will be implemented in approximately three months to allow measurements to be made over a period of one or more lunations In addition to the science mission NASA will use this mission to demonstrate optical communication technology away from low Earth orbit.

  20. SUDA: A Dust Mass Spectrometer for compositional surface mapping for the JUICE mission to the Galilean moons

    NASA Astrophysics Data System (ADS)

    Kempf, S.; Briois, C.; Cottin, H.; Engrand, C.; Gruen, E.; Hand, K. P.; Henkel, H.; Horanyi, M.; Lankton, M. R.; Lebreton, J.; Postberg, F.; Schmidt, J.; Srama, R.; Sternovsky, Z.; Thissen, R.; Tobie, G.; Szopa, C.; Zolotov, M. Y.

    2012-12-01

    We developed a dust mass spectrometer to measure the composition of ballistic dust particles populating the thin exospheres that were detected around each of the Galilean moons. Since these grains are direct samples from the moons' icy surfaces, unique composition data will be obtained that will help to define and constrain the geological activities on and below the moons' surface. The proposed instrument will make a vital contribution to ESA's planned JUICE mission and provide key answers to its main scientific questions about the surface composition, habitability, the icy crust, and exchange processes with the deeper interior of the Jovian icy moons Europa, Ganymede, and Callisto. The SUrface Dust Aanalyser (SUDA) is a time-of-flight, reflectron-type impact mass spectrometer, opti-mised for a high mass resolution which only weakly depends on the impact location. The small size (268×250×171 mm3), low mass (< 4 kg) and large sen-sitive area (220 cm2) makes the instrument well suited for the challenging demands of the JUICE mission to the Galilean moons Europa, Ganymede, and Callisto. A full-size prototype SUDA instrument was built in order to demonstrate its performance through calibra-tion experiments at the Heidelberg dust accelerator with a variety of cosmo-chemically relevant dust ana-logues. The effective mass resolution of m/Δm of 150-200 is achieved for mass range of interest m = 1-150.

  1. Mass transfer of PBDEs from plastic TV casing to indoor dust via three migration pathways--A test chamber investigation.

    PubMed

    Rauert, C; Harrad, S

    2015-12-01

    Polybrominated diphenyl ethers (PBDEs) are widely detected in humans with substantial exposure thought to occur in indoor environments and particularly via contact with indoor dust. Despite this, knowledge of how PBDEs migrate to indoor dust from products within which they are incorporated is scarce. This study utilises an in-house designed and built test chamber to investigate the relative significance of different mechanisms via which PBDEs transfer from source materials to dust, using a plastic TV casing treated with the Deca-BDE formulation as a model source. Experiments at both room temperature and 60°C revealed no detectable transfer of PBDEs from the TV casing to dust via volatilisation and subsequent partitioning. In contrast, substantial transfer of PBDEs to dust was detected when the TV casing was abraded using a magnetic stirrer bar. Rapid and substantial PBDE transfer to dust was also observed in experiments in which dust was placed in direct contact with the source. Based on these experiments, we suggest that for higher molecular weight PBDEs like BDE-209; direct dust:source contact is the principal pathway via which source-to-dust transfer occurs. PMID:26247685

  2. Dust formation in Milky Way-like galaxies

    NASA Astrophysics Data System (ADS)

    McKinnon, Ryan; Torrey, Paul; Vogelsberger, Mark

    2016-04-01

    We introduce a dust model for cosmological simulations implemented in the moving-mesh code AREPO and present a suite of cosmological hydrodynamical zoom-in simulations to study dust formation within galactic haloes. Our model accounts for the stellar production of dust, accretion of gas-phase metals on to existing grains, destruction of dust through local supernova activity, and dust driven by winds from star-forming regions. We find that accurate stellar and active galactic nuclei feedback is needed to reproduce the observed dust-metallicity relation and that dust growth largely dominates dust destruction. Our simulations predict a dust content of the interstellar medium which is consistent with observed scaling relations at z = 0, including scalings between dust-to-gas ratio and metallicity, dust mass and gas mass, dust-to-gas ratio and stellar mass, and dust-to-stellar mass ratio and gas fraction. We find that roughly two-thirds of dust at z = 0 originated from Type II supernovae, with the contribution from asymptotic giant branch stars below 20 per cent for z ≳ 5. While our suite of Milky Way-sized galaxies forms dust in good agreement with a number of key observables, it predicts a high dust-to-metal ratio in the circumgalactic medium, which motivates a more realistic treatment of thermal sputtering of grains and dust cooling channels.

  3. Supernova dust formation and the grain growth in the early universe: the critical metallicity for low-mass star formation

    NASA Astrophysics Data System (ADS)

    Chiaki, Gen; Marassi, Stefania; Nozawa, Takaya; Yoshida, Naoki; Schneider, Raffaella; Omukai, Kazuyuki; Limongi, Marco; Chieffi, Alessandro

    2015-01-01

    We investigate the condition for the formation of low-mass second-generation stars in the early Universe. It has been proposed that gas cooling by dust thermal emission can trigger fragmentation of a low-metallicity star-forming gas cloud. In order to determine the critical condition in which dust cooling induces the formation of low-mass stars, we follow the thermal evolution of a collapsing cloud by a one-zone semi-analytic collapse model. Earlier studies assume the dust amount in the local Universe, where all refractory elements are depleted on to grains, and/or assume the constant dust amount during gas collapse. In this paper, we employ the models of dust formation and destruction in early supernovae to derive the realistic dust compositions and size distributions for multiple species as the initial conditions of our collapse calculations. We also follow accretion of heavy elements in the gas phase on to dust grains, i.e. grain growth, during gas contraction. We find that grain growth well alters the fragmentation property of the clouds. The critical conditions can be written by the gas metallicity Zcr and the initial depletion efficiency fdep,0 of gas-phase metal on to grains, or dust-to-metal mass ratio, as (Zcr/10-5.5 Z⊙) = (fdep,0/0.18)-0.44 with small scatters in the range of Zcr = [0.06-3.2] × 10-5 Z⊙. We also show that the initial dust composition and size distribution are important to determine Zcr.

  4. GAMA/H-ATLAS: THE DUST OPACITY-STELLAR MASS SURFACE DENSITY RELATION FOR SPIRAL GALAXIES

    SciTech Connect

    Grootes, M. W.; Tuffs, R. J.; Andrae, E.; Popescu, C. C.; Pastrav, B.; Gunawardhana, M.; Taylor, E. N.; Kelvin, L. S.; Driver, S. P.; Liske, J.; Seibert, M.; Graham, Alister W.; Baes, M.; Baldry, I. K.; Bourne, N.; Brough, S.; Cooray, A.; Dariush, A.; De Zotti, G.; Dunne, L.; and others

    2013-03-20

    We report the discovery of a well-defined correlation between B-band face-on central optical depth due to dust, {tau}{sup f}{sub B}, and the stellar mass surface density, {mu}{sub *}, of nearby (z {<=} 0.13) spiral galaxies. This relation was derived from a sample of spiral galaxies taken from the Galaxy and Mass Assembly (GAMA) survey, which were detected in the FIR/submillimeter (submm) in the Herschel-ATLAS science demonstration phase field. Using a quantitative analysis of the NUV attenuation-inclination relation for complete samples of GAMA spirals categorized according to stellar mass surface density, we demonstrate that this correlation can be used to statistically correct for dust attenuation purely on the basis of optical photometry and Sersic-profile morphological fits. Considered together with previously established empirical relationships of stellar mass to metallicity and gas mass, the near linearity and high constant of proportionality of the {tau}{sub B}{sup f} - {mu}{sub *} relation disfavors a stellar origin for the bulk of refractory grains in spiral galaxies, instead being consistent with the existence of a ubiquitous and very rapid mechanism for the growth of dust in the interstellar medium. We use the {tau}{sub B}{sup f} - {mu}{sub *} relation in conjunction with the radiation transfer model for spiral galaxies of Popescu and Tuffs to derive intrinsic scaling relations between specific star formation rate (SFR), stellar mass, and stellar surface density, in which attenuation of the UV light used for the measurement of SFR is corrected on an object-to-object basis. A marked reduction in scatter in these relations is achieved which we demonstrate is due to correction of both the inclination-dependent and face-on components of attenuation. Our results are consistent with a general picture of spiral galaxies in which most of the submm emission originates from grains residing in translucent structures, exposed to UV in the diffuse interstellar

  5. Dust in Protoplanetary Disks: A Clue as to the Critical Mass of Planetary Cores

    NASA Astrophysics Data System (ADS)

    Hasegawa, Y.; Pudritz, R. E.

    Dust in protoplanetary disks is widely recognized as the building blocks of planets that are eventually formed in the disks. In the core accretion scenario, one of the standard theories of gas giant formation, the abundance of dust in disks (or metallicity, [Fe/H]) plays a crucial role in regulating the formation of cores of gas giants that proceeds via collisions of dust and planetesimals in disks. We present our recent progress on the relationship between the metallicity and planet formation, wherein planet formation frequencies (PFFs) as well as the critical mass of planetary cores (Mc,crit ) that can initiate gas accretion are statistically examined. We focus on three different planetary populations that are prominent in the distribution of observed exoplanets in the mass-semimajor axis diagram: hot Jupiters, exo-Jupiters that are densely populated around 1 AU, and low-mass planets in tight orbits, also known as super-Earths and hot Neptunes. We show that the resultant PFFs for both Jovian planets are correlated positively with the metallicity of disks whereas low-mass planets form efficiently for a wide range of metallicities (-0.6 ≤[Fe/H]≤ 0.6). This is consistent with the so-called Planet-Metallicity correlation that is inferred from both the radial velocity and transit observations. By plotting the statistically averaged value of Mc,crit (defined as hMc,crit i) as a function of metallicity, we find that the correlation originates from the behavior of hMc,crit i that increases steadily with metallicity for two kinds of the Jovian planets while the low-mass planets obtain a rather constant value for hMc,crit i. Such a different behavior in hMc,crit i enables one to define transition metallicities (TMs) above which the Jovian planets gain a larger value of hMc,crit i than the low-mass planets, and hence gas giant formation takes place more efficiently. We find that TMs appear at [Fe/H]' -0.2 to -0.4, and are sensitive to the important parameter that

  6. Dust control products at Hagerman National Wildlife Refuge, Texas: environmental safety and performance

    USGS Publications Warehouse

    Kunz, Bethany K.; Little, Edward E.

    2015-01-01

    Controlling fugitive dust while protecting natural resources is a challenge faced by all managers of unpaved roads. Unfortunately, road managers choosing between dust control products often have little objective environmental information to aid their decisions. To address this information gap, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collaborated on a field test of three dust control products with the objectives of (a) evaluating product performance under real-world conditions, (b) verifying the environmental safety of products identified as practically nontoxic in laboratory tests, and (c) testing the feasibility of several environmental monitoring techniques for use in dust control tests. In cooperation with refuge staff and product vendors, three products (one magnesium chloride plus binder, one cellulose, and one synthetic fluid plus binder) were applied in July 2012 to replicated road sections at the Hagerman National Wildlife Refuge in Texas. These sections were monitored periodically for 12 months after application. Product performance was assessed by mobile-mounted particulate-matter meters measuring production of fugitive dust and by observations of road conditions. Environmental safety was evaluated through on-site biological observations and leaching tests with samples of treated aggregate. All products reduced dust and improved surface condition during those 12 months. Planned environmental measurements were not always compatible with day-to-day refuge management actions; this incompatibility highlighted the need for flexible biological monitoring plans. As one of the first field tests of dust suppressants that explicitly incorporated biological endpoints, this effort provides valuable information for improving field tests and for developing laboratory or semifield alternatives.

  7. Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA

    NASA Technical Reports Server (NTRS)

    Indebetouw, R.; Matsuura, M.; Dwek, E.; Zanardo, G.; Barlow, M. J.; Baes, M.; Bouchet, P.; Burrows, D. N.; Chevalier, R.; Clayton, G. C.; Fransson, C.; Gaensler, B.; Kirshner, R.; Lakicevic, M.; Long, K. S.; Lundqvist, P.; Marti-Vidal, I.; Marcaide, J.; McCray, R.; Meixner, M.; Ng, C.-Y.; Park, S.; Sonneborn, G.; Staveley-Smith, L.; vanLoon, J.

    2014-01-01

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/ Submillimeter Array to observe SN1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 µm, 870 µm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 Solar Mass). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  8. Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2014-09-01

    Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (κ) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.

  9. Gas-to-dust mass ratios in local galaxies over a 2 dex metallicity range

    NASA Astrophysics Data System (ADS)

    Rémy-Ruyer, A.; Madden, S. C.; Galliano, F.; Galametz, M.; Takeuchi, T. T.; Asano, R. S.; Zhukovska, S.; Lebouteiller, V.; Cormier, D.; Jones, A.; Bocchio, M.; Baes, M.; Bendo, G. J.; Boquien, M.; Boselli, A.; DeLooze, I.; Doublier-Pritchard, V.; Hughes, T.; Karczewski, O. Ł.; Spinoglio, L.

    2014-03-01

    Aims: The goal of this paper is to analyse the behaviour of the gas-to-dust mass ratio (G/D) of local Universe galaxies over a wide metallicity range. We especially focus on the low-metallicity part of the G/D vs metallicity relation and investigate several explanations for the observed relation and scatter. Methods: We assembled a total of 126 galaxies, covering a 2 dex metallicity range and with 30% of the sample with 12 + log(O/H)≤ 8.0. We homogeneously determined the dust masses with a semi-empirical dust model including submm constraints. The atomic and molecular gas masses have been compiled from the literature. We used two XCO scenarios to estimate the molecular gas mass: the Galactic conversion factor, XCO,MW, and a XCO that depends on the metallicity XCO,Z (∝Z-2). We modelled the observed trend of the G/D with metallicity using two simple power laws (slope of -1 and free) and a broken power law. Correlations with morphological type, stellar masses, star formation rates, and specific star formation rates are also discussed. We then compared the observed evolution of the G/D with predictions from several chemical evolution models and explored different physical explanations for the observed scatter in the G/D values. Results: We find that out of the five tested galactic parameters, metallicity is the main physical property of the galaxy driving the observed G/D. The G/D versus metallicity relation cannot be represented by a single power law with a slope of -1 over the whole metallicity range. The observed trend is steeper for metallicities lower than ~8.0. A large scatter is observed in the G/D values for a given metallicity: in metallicity bins of ~0.1 dex, the dispersion around the mean value is ~0.37 dex. On average, the broken power law reproduces the observed G/D best compared to the two power laws (slope of -1 or free) and provides estimates of the G/D that are accurate to a factor of 1.6. The good agreement of observed values of the G/D and its

  10. Peering Through the Dust: NuSTAR Observations of Two FIRST-2MASS Red Quasars

    NASA Astrophysics Data System (ADS)

    LaMassa, Stephanie M.; Ricarte, Angelo; Glikman, Eilat; Urry, C. Megan; Stern, Daniel; Yaqoob, Tahir; Lansbury, George B.; Civano, Francesca; Boggs, Steve E.; Brandt, W. N.; Chen, Chien-Ting J.; Christensen, Finn E.; Craig, William W.; Hailey, Chuck J.; Harrison, Fiona; Hickox, Ryan C.; Koss, Michael; Ricci, Claudio; Treister, Ezequiel; Zhang, Will

    2016-03-01

    Some reddened quasars appear to be transitional objects in the paradigm of merger-induced black hole growth/galaxy evolution, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS-selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured (NH,Z = (2.1 ± 0.2) × 1022 cm-2) and F2M 1227+3214 is mildly absorbed ({N}{{H},{{Z}}}={3.4}-0.7+0.8× {10}21 cm-2) along the line of sight, heavier global obscuration may be present in both sources, with {N}{{H},{{S}}}={3.7}-2.6+4.1× {10}23 cm-2 and <5.5 × 1023 cm-2 for F2M 0830+3759 and F2M 1227+3214, respectively. F2M 0830+3759 also has an excess of soft X-ray emission below 1 keV, which is well accommodated by a model where 7% of the intrinsic X-ray emission from the active galactic nucleus (AGN) is scattered into the line of sight. While F2M 1227+3214 has a dust-to-gas ratio (E(B - V)/NH) consistent with the Galactic value, the value of E(B - V)/NH for F2M 0830+3759 is lower than the Galactic standard, consistent with the paradigm that the dust resides on galactic scales while the X-ray reprocessing gas originates within the dust sublimation zone of the broad-line region. The X-ray and 6.1 μm luminosities of these red quasars are consistent with the empirical relations derived for high-luminosity, unobscured quasars, extending the parameter space of obscured AGNs previously observed by NuSTAR to higher luminosities.

  11. OUTBURST DUST PRODUCTION OF COMET 29P/SCHWASSMANN-WACHMANN 1

    SciTech Connect

    Hosek, Matthew W. Jr.; Blaauw, Rhiannon C.; Cooke, William J.; Suggs, Robert M.

    2013-05-15

    Multi-aperture photometry of Comet 29P/Schwassmann-Wachmann 1 was conducted on Johnson-Cousins R-band observations spanning 2011 May 1-9 and 2012 June 6-July 3. The comet was observed in outburst on 2011 May 3 and 2012 July 1, during which its brightness increased by 2.2 and 2.1 mag, respectively, as measured through a 10 arcsec aperture. Dust production before and after each outburst is calculated using the parameter Af {rho}, which is converted to a lower limit on the dust production rate based on dust models and derived nuclear properties from other studies. Both outbursts are accompanied by large increases in dust production, Af {rho} by a factor of {approx}6.5-7 and dust production rate by a factor of {approx}18-23. In addition, variations in the dust brightness profile of the coma are examined during the events. The profile is observed to steepen significantly at the beginning of each outburst and then slowly return to pre-outburst values, mirroring the behavior of Af {rho}. The start of an outbound 'ripple' of dust in the profile might be observed as the comet returns to its pre-outburst state, although this cannot be confirmed. Using a simple model of the 2011 May 3 outburst, an estimated lower limit of (2.6 {+-} 0.7) Multiplication-Sign 10{sup 8} kg of dust was released during the event. If this is representative of a typical outburst of 29P, then it is estimated that outbursts account for a lower limit of 80{sub -30}{sup +20}% of the total material ejected by the comet per year.

  12. HERschel Observations of Edge-on Spirals (HEROES). I. Far-infrared morphology and dust mass determination

    NASA Astrophysics Data System (ADS)

    Verstappen, J.; Fritz, J.; Baes, M.; Smith, M. W. L.; Allaert, F.; Bianchi, S.; Blommaert, J. A. D. L.; De Geyter, G.; De Looze, I.; Gentile, G.; Gordon, K. D.; Holwerda, B. W.; Viaene, S.; Xilouris, E. M.

    2013-08-01

    Context. Edge-on spiral galaxies with prominent dust lanes provide us with an excellent opportunity to study the distribution and properties of the dust within them. The HEROES project was set up to observe a sample of seven large edge-on galaxies across various wavelengths for this investigation. Aims: Within this first paper, we present the Herschel observations and perform a qualitative and quantitative analysis on them, and we derive some global properties of the far infrared and submillimetre emission. Methods: We determine horizontal and vertical profiles from the Herschel observations of the galaxies in the sample and describe the morphology. Modified black-body fits to the global fluxes, measured using aperture photometry, result in dust temperatures and dust masses. The latter values are compared to those that are derived from radiative transfer models taken from the literature. Results: On the whole, our Herschel flux measurements agree well with archival values. We find that the exponential horizontal dust distribution model often used in the literature generally provides a good description of the observed horizontal profiles. Three out of the seven galaxies show signatures of extended vertical emission at 100 and 160 μm at the 5σ level, but in two of these it is probably due to deviations from an exactly edge-on orientation. Only for NGC 4013, a galaxy in which vertically extended dust has already been detected in optical images, we can detect vertically extended dust, and the derived scaleheight agrees with the value estimated through radiative transfer modelling. Our analysis hints at a correlation between the dust scaleheight and its degree of clumpiness, which we infer from the difference between the dust masses as calculated from modelling of optical data and from fitting the spectral energy distribution of Herschel datapoints. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia

  13. Hurdles in low k1 mass production

    NASA Astrophysics Data System (ADS)

    Yim, Donggyu; Yang, Hyunjo; Park, Chanha; Hong, Jongkyun; Choi, Jaeseung

    2005-05-01

    As the optical lithography pushes toward its theoretical resolution limit 0.25k1, the application of aggressive Resolution Enhancement Techniques (RETs) are required in order to ensure necessary resolution, sufficient process window, and reasonable MEEF in critical layers. When chip makers are adopting RETs in low k1 device, there are a lot of crucial factors to take into account in the development and mass production. Those hurdles are not only difficult to overcome but also highly risky to the company, which adopts low k1 mass production strategy. But, low k1 production strategy is very attractive to all chip makers, owing to improving production capacity and cost of ownership. So, low k1 technology has been investigated by many lithography engineers. Lots of materials have been introduced. Most of them are just in RnD level. In this study, low k1 mass production issues shall be introduced, mainly. The definition of low k1 in mass production shall be suggested. And, a lot of low_k1 issues shall be introduced, also. Most of them were investigated/experienced in RnD development stage and final mass production line. Low k1 mass production, is some what different from only RnD development.

  14. Product screening for sources of halogenated flame retardants in Canadian house and office dust.

    PubMed

    Abbasi, Golnoush; Saini, Amandeep; Goosey, Emma; Diamond, Miriam L

    2016-03-01

    Human exposure to halogenated flame retardants (HFRs) such as polybrominated diphenyl ethers (PBDEs) and their replacements, can be related to exposure to indoor dust and direct contact with HFR-containing products. This study aimed to identify electronic products that contributed to HFRs measured in indoor dust and to develop a screening method for identifying HFRs in hard polymer products. Concentrations of 10 PBDEs and 12 halogenated replacements in dust and surface wipe samples of hard polymer casings of electronic products plus Br in the surfaces of those casing measured using X-ray fluorescence (XRF) were analyzed from 35 homes and 10 offices in Toronto (ON, Canada). HFR concentrations in dust and product wipes were positively correlated. Thus, we hypothesize that electronic products with the highest HFR concentrations contribute the most to concentrations in dust, regardless of the volatility of the HFR. Abundant HFRs in dust and product wipes were PBDEs (BDE-47, 99, 100, 153, 154, 183, 209), TDCPP, DBDPE, EH-TBB and BEHTBP. Older CRT TVs had the highest concentration of BDE-209 of all products tested. This was followed by higher concentrations of HFRs in PCs, Audio/Video (A/V) devices, small household appliances (HHAs) and flat screen TVs. The removal of HFRs from polymer surfaces using wipes supports concerns that HFRs could be transferred from these surfaces to hands as a result of direct contact with HFR-containing products. Surface wipe testing shows promise for screening additive HFRs. In comparison, the Br-content obtained using a handheld XRF analyzer did not correspond to concentrations obtained from surface wipe testing. PMID:26747994

  15. Mass spectrometry in natural product chemistry.

    PubMed

    Clayton, E; Hill, H C; Reed, R I

    1966-01-01

    Some mass spectrometric techniques are described which seem applicable to investigating problems in natural product chemistry. One example is of a sample of 5 mcg of a compound being identified by comparison with an authentic sample of prostaglandin derivative. Compared were mass, ion content, and structure. In the prostaglandin/unknown substance comparison, high-resolution mass spectrometry resolved a quandary: apparent additional ions present in the unknown substance were shown to be an impurity. PMID:12262324

  16. Mass Influx of Cosmic Dust Estimated From Vertical Transport of Meteoric Metals

    NASA Astrophysics Data System (ADS)

    Liu, Alan Z.; Guo, Yafang; Gardner, Chester S.

    2016-04-01

    The mesospheric metal layers are formed by the vaporization of high-speed cosmic dust particles in the lower thermosphere and upper mesosphere. The vaporized atoms and ions are transported downward by waves and turbulence to chemical sinks below 85 km, where they form stable compounds. These compounds condense onto meteoric smoke particles and are then transported to the winter pole where they eventually settle onto the surface. The downward fluxes of the metal atoms are directly related to their meteoric influxes and chemical loss rates. In this paper we use Doppler lidar measurements of Na and Fe fluxes made by the University of Illinois and University of Colorado groups, and a chemical ablation model (CABMOD) developed at the University of Leeds, to constrain the velocity/mass distribution of the meteoroids entering the atmosphere and to derive an improved estimate for the global influx of cosmic dust. We find that the particles responsible for injecting a large fraction of the ablated material into the Earth's upper atmosphere, enter at relatively slow speeds and originate primarily from the Jupiter Family of Comets. The global mean Na influx is 21,500±1,100 atoms/cm2/s, which equals 372±18 kg/d for the global input of Na vapor and 186±24 t/d for the global influx of cosmic dust. The global mean Fe influx is 131,000±36,000 atoms/cm2/s, which equals 5.5±1.5 t/d for the global input of Na vapor.

  17. Slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for steelmaking flue dust analysis

    NASA Astrophysics Data System (ADS)

    Coedo, A. G.; Dorado, T.; Padilla, I.; Maibusch, R.; Kuss, H.-M.

    2000-02-01

    A commercial atomic absorption graphite furnace (AAGF), with a self-made adapter and valve system, was used as a slurry sampling cell for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The system was applied to the determination of As, Sn, Sb, Se, Te, Bi, Cd, V, Ti and Mo in steelmaking flue dusts. Experimental conditions with respect to ETV and ICP-MS operating parameters were optimized. Compared to aqueous solutions, slurry samples were found to present better analyte transport. Microgram amounts of Rh were used to reduce the difference in analyte response in sensitivity for aqueous solutions of the tested analytes. No such increasing effect was observed for slurry samples and aqueous standards. An added quantity of Rh acting as modifier/carrier resulted in an increase for the same analytes in matrix-slurry solutions, even the addition of an extra Rh quantity has resulted in a decrease in the signals. The effect of Triton X-100 (used as a dispersant agent) on analyte intensity and precision was also studied. External calibration from aqueous standards spiked with 100 μg ml -1 Rh was performed to quantified 0.010 g/100 ml slurry samples. Results are presented for a certified reference electrical arc furnace flue dust (EAF): CRM-876-1 (Bureau of Analysis Samples Ltd., Cleveland, UK), a reference sample of coke ashes X-3705 (from AG der Dillinger Hüttenwerke, Germany), and a representative sample of EAF flue dust from a Spanish steelmaking company (CENIM-1). For the two reference materials an acceptable agreement with certificate values was achieved, and the results for the CENIM sample matched with those obtained from conventional nebulization solution.

  18. Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA

    NASA Astrophysics Data System (ADS)

    Indebetouw, R.; Matsuura, M.; Dwek, E.; Zanardo, G.; Barlow, M. J.; Baes, M.; Bouchet, P.; Burrows, D. N.; Chevalier, R.; Clayton, G. C.; Fransson, C.; Gaensler, B.; Kirshner, R.; Lakićević, M.; Long, K. S.; Lundqvist, P.; Martí-Vidal, I.; Marcaide, J.; McCray, R.; Meixner, M.; Ng, C.-Y.; Park, S.; Sonneborn, G.; Staveley-Smith, L.; Vlahakis, C.; van Loon, J.

    2014-02-01

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 μm, 870 μm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M ⊙). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  19. DUST PRODUCTION AND PARTICLE ACCELERATION IN SUPERNOVA 1987A REVEALED WITH ALMA

    SciTech Connect

    Indebetouw, R.; Chevalier, R.; Matsuura, M.; Barlow, M. J.; Dwek, E.; Zanardo, G.; Baes, M.; Bouchet, P.; Burrows, D. N.; Clayton, G. C.; Fransson, C.; Lundqvist, P.; Gaensler, B.; Kirshner, R.; Lakićević, M.; Long, K. S.; Meixner, M.; Martí-Vidal, I.; Marcaide, J.; and others

    2014-02-10

    Supernova (SN) explosions are crucial engines driving the evolution of galaxies by shock heating gas, increasing the metallicity, creating dust, and accelerating energetic particles. In 2012 we used the Atacama Large Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed supernovae since the invention of the telescope. We present spatially resolved images at 450 μm, 870 μm, 1.4 mm, and 2.8 mm, an important transition wavelength range. Longer wavelength emission is dominated by synchrotron radiation from shock-accelerated particles, shorter wavelengths by emission from the largest mass of dust measured in a supernova remnant (>0.2 M {sub ☉}). For the first time we show unambiguously that this dust has formed in the inner ejecta (the cold remnants of the exploded star's core). The dust emission is concentrated at the center of the remnant, so the dust has not yet been affected by the shocks. If a significant fraction survives, and if SN 1987A is typical, supernovae are important cosmological dust producers.

  20. On the Evolution of the Mass Distribution on Interstellar Dust Grains

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Hee

    1995-01-01

    Mass distributions of interstellar dust grains have been determined using the objective maximum entropy method based on modeling the wavelength dependence of interstellar extinction and polarization in various environments. For the extinction analysis, we adopted bare spherical silicate and graphite grains. The mass distributions found are qualitatively similar to a widely used power-law distribution, however they depart significantly to achieve a good fit to the data (the detailed structure depends on the chemical composition). We also show how the mass distribution falls off smoothly toward large sizes (radii > 0.3 μm). At small sizes (< 0.02 μm) only the total mass of grains can be constrained. Most of the analysis for the polarization is based on bare silicate grains. Infinite cylinders as well as spheroids are considered. The aligned grain mass distributions found bear little resemblance to a power law. Compared to the mass distribution based on extinction, there is a close similarity for large grains, but it is not necessary to have nearly as many small grains. An oblate shape is preferred to prolate. Among materials explored, silicate is the most satisfactory. An interesting problem arises in explaining the wavelength dependence of ultraviolet interstellar polarization, if the refractive index of "astronomical silicate is adopted, but the problem is much reduced if the rise of electronic absorption is simply shifted by about 1 mu m^{-1} to higher frequencies. While this is not unlike obsidian, a volcanic glass, laboratory measurements for many more amorphous silicates are needed. There is a systematic reduction in the relative number of small grains with a<0.1murm m in the more dense regions. On the other hand, there is not any noticeable variation for large grains. This suggests that aggregation plays a major role in the variation of the mass distribution as the medium becomes more dense (with shattering operating in reverse). Theoretical studies of

  1. Manganese concentrations in soil and settled dust in an area with historic ferroalloy production

    PubMed Central

    Pavilonis, Brian T.; Lioy, Paul J.; Guazzetti, Stefano; Bostick, Benjamin C.; Donna, Filippo; Peli, Marco; Zimmerman, Neil J.; Bertrand, Patrick; Lucas, Erika; Smith, Donald R.; Georgopoulos, Panos G.; Mi, Zhongyuan; Royce, Steven G.; Lucchini, Roberto G.

    2015-01-01

    Ferroalloy production can release a number of metals into the environment, of which manganese (Mn) is of major concern. Other elements include lead, iron, zinc, copper, chromium, and cadmium. Manganese exposure derived from settled dust and suspended aerosols can cause a variety of adverse neurological effects to chronically exposed individuals. To better estimate the current levels of exposure, this study quantified metal levels in dust collected inside homes (n=85), outside homes (n=81), in attics (n=6), and in surface soil (n=252) in an area with historic ferroalloy production. Metals contained in indoor and outdoor dust samples were quantified using inductively coupled plasma optical emission spectroscopy while attic and soil measurements were made with a XRF instrument. Mean Mn concentrations in soil (4600 μg/g) and indoor dust (870 μg/g) collected within 0.5 km of a plant exceeded levels previously found in suburban and urban areas, but did decrease outside 1.0 km to the upper end of background concentrations. Mn concentrations in attic dust were approximately 120 times larger than other indoor dust levels, consistent with historical emissions that yielded high airborne concentrations in the region. Considering the potential health effects that are associated with chronic manganese inhalation and ingestion exposure, remediation of soil near the plants and frequent, on-going hygiene indoors may decrease residential exposure and the likelihood of adverse health effects. PMID:25335867

  2. Manganese concentrations in soil and settled dust in an area with historic ferroalloy production.

    PubMed

    Pavilonis, Brian T; Lioy, Paul J; Guazzetti, Stefano; Bostick, Benjamin C; Donna, Filippo; Peli, Marco; Zimmerman, Neil J; Bertrand, Patrick; Lucas, Erika; Smith, Donald R; Georgopoulos, Panos G; Mi, Zhongyuan; Royce, Steven G; Lucchini, Roberto G

    2015-01-01

    Ferroalloy production can release a number of metals into the environment, of which manganese (Mn) is of major concern. Other elements include lead, iron, zinc, copper, chromium, and cadmium. Mn exposure derived from settled dust and suspended aerosols can cause a variety of adverse neurological effects to chronically exposed individuals. To better estimate the current levels of exposure, this study quantified the metal levels in dust collected inside homes (n=85), outside homes (n=81), in attics (n=6), and in surface soil (n=252) in an area with historic ferroalloy production. Metals contained in indoor and outdoor dust samples were quantified using inductively coupled plasma optical emission spectroscopy, whereas attic and soil measurements were made with a X-ray fluorescence instrument. Mean Mn concentrations in soil (4600 μg/g) and indoor dust (870 μg/g) collected within 0.5 km of a plant exceeded levels previously found in suburban and urban areas, but did decrease outside 1.0 km to the upper end of background concentrations. Mn concentrations in attic dust were ~120 times larger than other indoor dust levels, consistent with historical emissions that yielded high airborne concentrations in the region. Considering the potential health effects that are associated with chronic Mn inhalation and ingestion exposure, remediation of soil near the plants and frequent, on-going hygiene indoors may decrease residential exposure and the likelihood of adverse health effects. PMID:25335867

  3. Intermittent dust mass loss from activated asteroid P/2013 P5 (PANSTARRS)

    SciTech Connect

    Moreno, F.; Pozuelos, F.

    2014-02-01

    We present observations and models of the dust environment of activated asteroid P/2013 P5 (PANSTARRS). The object displayed a complex morphology during the observations, with the presence of multiple tails. We combined our own observations, all made with instrumentation attached to the 10.4 m Gran Telescopio Canarias on La Palma, with previously published Hubble Space Telescope images to build a model aimed at fitting all the observations. Altogether, the data cover a full three month period of observations which can be explained by intermittent dust loss. The most plausible scenario is that of an asteroid rotating with the spinning axis oriented perpendicular to the orbit plane and losing mass from the equatorial region, consistent with rotational break-up. Assuming that the ejection velocity of the particles (v ∼ 0.02-0.05 m s{sup –1}) corresponds to the escape velocity, the object diameter is constrained to ∼30-130 m for bulk densities 3000-1000 kg m{sup –3}.

  4. An empirical determination of the dust mass absorption coefficient, κd, using the Herschel Reference Survey

    NASA Astrophysics Data System (ADS)

    Clark, Christopher J. R.; Schofield, Simon P.; Gomez, Haley L.; Davies, Jonathan I.

    2016-06-01

    We use the published photometry and spectroscopy of 22 galaxies in the Herschel Reference Survey to determine that the value of the dust mass absorption coefficient κd at a wavelength of 500 μm is kappa _{500} = 0.051^{+0.070}_{-0.026} m^{2 kg^{-1}}. We do so by taking advantage of the fact that the dust-to-metals ratio in the interstellar medium of galaxies appears to be constant. We argue that our value for κd supersedes that of James et al. - who pioneered this approach for determining κd - because we take advantage of superior data, and account for a number of significant systematic effects that they did not consider. We comprehensively incorporate all methodological and observational contributions to establish the uncertainty on our value, which represents a marked improvement on the oft-quoted `order-of-magnitude' uncertainty on κd. We find no evidence that the value of κd differs significantly between galaxies, or that it correlates with any other measured or derived galaxy properties. We note, however, that the availability of data limits our sample to relatively massive (109.7 < M⋆ < 1011.0 M⊙), high metallicity (8.61 < [ 12 + log_{10} fracOH ] < 8.86) galaxies; future work will allow us to investigate a wider range of systems.

  5. Ice sheet mass loss caused by dust and black carbon accumulation

    NASA Astrophysics Data System (ADS)

    Goelles, T.; Bøggild, C. E.; Greve, R.

    2015-09-01

    Albedo is the dominant factor governing surface melt variability in the ablation area of ice sheets and glaciers. Aerosols such as mineral dust and black carbon (soot) accumulate on the ice surface and cause a darker surface and therefore a lower albedo. The darkening effect on the ice surface is currently not included in sea level projections, and the effect is unknown. We present a model framework which includes ice dynamics, aerosol transport, aerosol accumulation and the darkening effect on ice albedo and its consequences for surface melt. The model is applied to a simplified geometry resembling the conditions of the Greenland ice sheet, and it is forced by several temperature scenarios to quantify the darkening effect of aerosols on future mass loss. The effect of aerosols depends non-linearly on the temperature rise due to the feedback between aerosol accumulation and surface melt. According to our conceptual model, accounting for black carbon and dust in future projections of ice sheet changes until the year 3000 could induce an additional volume loss of 7 %. Since we have ignored some feedback processes, the impact might be even larger.

  6. GIADA: shining a light on the monitoring of the comet dust production from the nucleus of 67P/Churyumov-Gerasimenko

    NASA Astrophysics Data System (ADS)

    Della Corte, V.; Rotundi, A.; Fulle, M.; Gruen, E.; Weissman, P.; Sordini, R.; Ferrari, M.; Ivanovski, S.; Lucarelli, F.; Accolla, M.; Zakharov, V.; Mazzotta Epifani, E.; Lopez-Moreno, J. J.; Rodriguez, J.; Colangeli, L.; Palumbo, P.; Bussoletti, E.; Crifo, J. F.; Esposito, F.; Green, S. F.; Lamy, P. L.; McDonnell, J. A. M.; Mennella, V.; Molina, A.; Morales, R.; Moreno, F.; Ortiz, J. L.; Palomba, E.; Perrin, J. M.; Rietmeijer, F. J. M.; Rodrigo, R.; Zarnecki, J. C.; Cosi, M.; Giovane, F.; Gustafson, B.; Herranz, M. L.; Jeronimo, J. M.; Leese, M. R.; Lopez-Jimenez, A. C.; Altobelli, N.

    2015-11-01

    Context. During the period between 15 September 2014 and 4 February 2015, the Rosetta spacecraft accomplished the circular orbit phase around the nucleus of comet 67P/Churyumov-Gerasimenko (67P). The Grain Impact Analyzer and Dust Accumulator (GIADA) onboard Rosetta monitored the 67P coma dust environment for the entire period. Aims: We aim to describe the dust spatial distribution in the coma of comet 67P by means of in situ measurements. We determine dynamical and physical properties of cometary dust particles to support the study of the production process and dust environment modification. Methods: We analyzed GIADA data with respect to the observation geometry and heliocentric distance to describe the coma dust spatial distribution of 67P, to monitor its activity, and to retrieve information on active areas present on its nucleus. We combined GIADA detection information with calibration activity to distinguish different types of particles that populate the coma of 67P: compact particles and fluffy porous aggregates. By means of particle dynamical parameters measured by GIADA, we studied the dust acceleration region. Results: GIADA was able to distinguish different types of particles populating the coma of 67P: compact particles and fluffy porous aggregates. Most of the compact particle detections occurred at latitudes and longitudes where the spacecraft was in view of the comet's neck region of the nucleus, the so-called Hapi region. This resulted in an oscillation of the compact particle abundance with respect to the spacecraft position and a global increase as the comet moved from 3.36 to 2.43 AU heliocentric distance. The speed of these particles, having masses from 10-10 to 10-7 kg, ranged from 0.3 to 12.2 m s-1. The variation of particle mass and speed distribution with respect to the distance from the nucleus gave indications of the dust acceleration region. The influence of solar radiation pressure on micron and submicron particles was studied. The

  7. Probing Ancient Mass Loss with AKARI's Extended Thermal Dust Emission Objects

    NASA Astrophysics Data System (ADS)

    Tomasino, Rachael L.; Ueta, Toshiya; Yamamura, Issei; Izumiura, Hideyuki

    We present the method for the calibration and analysis of 166 far-IR extended thermal dust emission objects that were observed with AKARI’s FIS detector. The primary goal of the analysis of this data set is to map the circumstellar shells of evolved stars in detail to understand the ancient history of dusty mass loss. After establishing an extended aperture photometry method, we re-characterize the flux dependent slow transient response correction factors for each of the four wavelength bands and propose a new flux calibration method for extended sources. Using these new correction factors, the photometric measurements are made using a extended aperture which is defined by a background + 3σ threshold. With photometry measurements for each of the four FIS bands, an SED of a modified blackbody was fit to produce the emissivity beta, effective temperature, and color correction factor.

  8. Observation of Asian Mineral Dust Particles in Japan by a Single-Particle Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Matsumoto, J.; Takahashi, K.; Matsumi, Y.; Sugimoto, N.; Matsui, I.; Shimizu, A.

    2005-12-01

    The Asian mineral dust (Kosa) particles, emitted from the desert area of inland China, are characteristic of East Asian aerosols. The Kosa particles are important as regional carriers of various materials, especially in spring when the stormy dusts are transported to Japan and Pacific Ocean. In this study, the chemical mixing state of each atmospheric aerosol was measured individually by a laser-based time-of-flight mass spectrometer (TOFMS) to discuss chemical changes of Kosa particles during the transport. Observation was conducted at Tsukuba (36.05°N, 140.12°E) in April and May 2004. The LIDAR measurement was also carried out to determine the Kosa events. To classify the source of the air mass, the NOAA-HYSPLIT backward trajectory was applied. For the TOFMS instrument, particles with μm and sub-μm diameters were detected. The polarity of ion detection was altered every minute. During 30 days, the numbers of logged mass spectra (MS) were 5993 and 4382 for positive and negative ions, respectively. When the MS of ambient aerosols were compared with that of the standard Kosa sample, sulfate- and nitrate-mixed Kosa particles were found. To explore the mixing state of particles further, classification of the particles by the ART-2a algorithm was adopted. NO2-, NO3-, HSO4-, SiO2-, SiO3-, Cl- and NaCl2- were focused. Finally, particles were classified to 4 categories as A: sulfate and sulfate-rich mineral; B: sulfate-poor mineral; C: sea salt; D: unidentified. The relative fractions of A were 30 % and 1 % for a Kosa event and a maritime air mass, respectively. Note that the air mass for Kosa event case passed over the coast region of China, where SOx emission was intensive. It was reasonable that sulfate was internally mixed with Kosa particles and transported to Japan. Consequently, it was confirmed experimentally that Kosa particles are important as carriers of pollutants in the rim region of Pacific Ocean. Comparison with the observation in 2005 is also shown.

  9. A Search for Stellar Dust Production in Leo P, a Nearby Analog of High Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Boyer, Martha; McDonald, Iain; McQuinn, Kristen; Skillman, Evan; Sonneborn, George; Srinivasan, Sundar; van Loon, Jacco Th.; Zijlstra, Albert; Sloan, Greg

    2016-08-01

    The origin of dust in the early Universe is a matter of debate. One of the main potential dust contributors are Asymptotic Giant Branch (AGB) stars, and several studies have been devoted to investigating whether and how AGB dust production changes in metal-poor environments. Of particular interest are the most massive AGB stars (8-10 Msun), which can in principle enter the dust-producing phase <50 Myr after they form. However, these stars cannot produce their own condensable material (unlike carbon AGB stars), so the efficiency of dust production decreases with metallicity. Evidence for dust production in massive AGB stars more metal-poor than the Magellanic Clouds is scarce due both to the rarity of chemically-unevolved, star-forming systems reachable in the infrared and to the short lifetimes of these stars. The recently discovered galaxy Leo P provides an irresistible opportunity to search for these massive AGB stars: Leo P is a gas-rich, star-forming galaxy, it is nearby enough for resolved star photometry with Spitzer, and its interstellar medium is 0.4 dex more metal-poor than any other accessible star-forming galaxy. Models predict ~3 massive AGB stars may be present in Leo P, and optical HST observations reveal 7 candidates. We propose to use Spitzer to determine whether these stars are dusty, providing valuable constraints to the dust contribution from AGB stars up to at least redshift 3.2, or 11.7 Gyr ago, when massive spheroidals and Galactic globular clusters were still forming. This is a gain of 2.8 Gyr compared to other accessible galaxies. We also request 1 orbit of joint HST time to confirm whether the AGB candidates in Leo P are indeed massive AGB stars belonging to the galaxy. These observations will provide information crucial for potential JWST followup spectroscopy.

  10. A novel brominated triazine-based flame retardant (TTBP-TAZ) in plastic consumer products and indoor dust.

    PubMed

    Ballesteros-Gómez, Ana; de Boer, Jacob; Leonards, Pim E G

    2014-04-15

    The presence of a novel brominated flame retardant named 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) is reported for the first time in plastic parts of consumer products and indoor dust samples. TTBP-TAZ was identified by untargeted screening and can be a replacement of the banned polybrominated diphenyl ethers. Analysis techniques based on ambient mass spectrometry and on liquid chromatography with atmospheric pressure chemical ionization combined with high resolution time-of-flight mass spectrometry were developed for the screening, detection and quantification of this low volatility and high molecular weight compound. TTBP-TAZ was present in 8 of 13 plastic parts of consumer products (from mainly electric and electronic equipment acquired in 2012) at estimated concentrations of 0.01-1.9% by weight of the product (%, w/w). It was not present in any of the older 13 plastic samples that were collected in a recycling park (manufacture date before 2006), this suggests a recent use of TTBP-TAZ. It was also found in 9 of 17 house dust samples in the range of 160-22150 ng g(-1), with the highest levels being found in samples collected on electronic and electrical equipment. These preliminary results highlight the need for further research on TTBP-TAZ and the potential of using alternative analysis methods for the identification of new flame retardants. PMID:24666318

  11. Integrated hydrometallurgical process for production of zinc from electric arc furnace dust in alkaline medium.

    PubMed

    Youcai, Z; Stanforth, R

    2000-12-30

    In this study, a novel and integrated hydrometallurgical process for the production of zinc powder from electric arc furnace (EAF) dust in alkaline medium is reported. The dust is firstly hydrolysed in water, and then fused in caustic soda at 350 degrees C for 1h, followed by leaching in alkaline solution in which both zinc and lead are effectively extracted. Zinc powder is then produced by electrowinning from the leach solution after the lead is selectively removed by precipitation using sodium sulphide as precipitant. The EAF dust tested contained 25% Zn, 1.8% Pb and 33% Fe. It was found that 38% of zinc and 68% of lead could be extracted from the dust when leached directly in caustic soda solution. Leaching of zinc increased to 80% when dust was directly fused with caustic soda followed by alkaline leaching. However, the leaching further increased to 95% when the dust was hydrolysed first with water before fusion. Zinc powder with a purity of 99.95% was then produced by electrowinning from the lead depleted solution. Stainless electrodes were used as both anode and cathode. PMID:11080580

  12. Non-targeted screening of house dust samples using accurate mass TOFMS

    EPA Science Inventory

    House dust exists as an environmental repository of chemicals to which we are exposed in our homes. A growing number of studies have targeted select persistent organic and inorganic pollutants found in house dust. Many have concluded that dust exists as an important human expos...

  13. Vertically-resolved profiles of mass concentrations and particle backscatter coefficients of Asian dust plumes derived from lidar observations of silicon dioxide.

    PubMed

    Noh, Youngmin; Müller, Detlef; Shin, Sung-Kyun; Shin, Dongho; Kim, Young J

    2016-01-01

    This study presents a method to retrieve vertically-resolved profiles of dust mass concentrations by analyzing Raman lidar signals of silicon dioxide (quartz) at 546nm. The observed particle plumes consisted of mixtures of East Asian dust with anthropogenic pollution. Our method for the first time allows for extracting the contribution of the aerosol component "pure dust" contained in the aerosol type "polluted dust". We also propose a method that uses OPAC (Optical Properties of Aerosols and Clouds) and the mass concentrations profiles of dust in order to derive profiles of backscatter coefficients of pure dust in mixed dust/pollution plumes. The mass concentration of silicon dioxide (quartz) in the atmosphere can be estimated from the backscatter coefficient of quartz. The mass concentration of dust is estimated by the weight percentage (38-77%) of mineral quartz in Asian dust. The retrieved dust mass concentrations are classified into water soluble, nucleation, accumulation, mineral-transported and coarse mode according to OPAC. The mass mixing ratio of 0.018, 0.033, 0.747, 0.130 and 0.072, respectively, is used. Dust extinction coefficients at 550nm were calculated by using OPAC and prescribed number concentrations for each of the 5 components. Dust backscatter coefficients were calculated from the dust extinction coefficients on the basis of a lidar ratio of 45±3sr at 532nm. We present results of quartz-Raman measurements carried out on the campus of the Gwangju Institute of Science and Technology (35.10°N, 126.53°E) on 15, 16, and 21 March 2010. PMID:25937543

  14. Morphology, spatial distribution, and concentration of flame retardants in consumer products and environmental dusts using scanning electron microscopy and Raman micro-spectroscopy.

    PubMed

    Wagner, Jeff; Ghosal, Sutapa; Whitehead, Todd; Metayer, Catherine

    2013-09-01

    We characterized flame retardant (FR) morphologies and spatial distributions in 7 consumer products and 7 environmental dusts to determine their implications for transfer mechanisms, human exposure, and the reproducibility of gas chromatography-mass spectrometry (GC-MS) dust measurements. We characterized individual particles using scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS). Samples were screened for the presence of 3 FR constituents (bromine, phosphorous, non-salt chlorine) and 2 metal synergists (antimony and bismuth). Subsequent analyses of select samples by RMS enabled molecular identification of the FR compounds and matrix materials. The consumer products and dust samples possessed FR elemental weight percents of up to 36% and 31%, respectively. We identified 24 FR-containing particles in the dust samples and classified them into 9 types based on morphology and composition. We observed a broad range of morphologies for these FR-containing particles, suggesting FR transfer to dust via multiple mechanisms. We developed an equation to describe the heterogeneity of FR-containing particles in environmental dust samples. The number of individual FR-containing particles expected in a 1-mg dust sample with a FR concentration of 100ppm ranged from <1 to >1000 particles. The presence of rare, high-concentration bromine particles was correlated with decabromodiphenyl ether concentrations obtained via GC-MS. When FRs are distributed heterogeneously in highly concentrated dust particles, human exposure to FRs may be characterized by high transient exposures interspersed by periods of low exposure, and GC-MS FR concentrations may exhibit large variability in replicate subsamples. Current limitations of this SEM/EDS technique include potential false negatives for volatile and chlorinated FRs and greater quantitation uncertainty for brominated FR in aluminum-rich matrices. PMID:23739093

  15. Morphology, Spatial Distribution, and Concentration of Flame Retardants in Consumer Products and Environmental Dusts using Scanning Electron Microscopy and Raman Micro-spectroscopy

    PubMed Central

    WAGNER, JEFF; GHOSAL, SUTAPA; WHITEHEAD, TODD; METAYER, CATHERINE

    2013-01-01

    We characterized flame retardant (FR) morphologies and spatial distributions in 7 consumer products and 7 environmental dusts to determine their implications for transfer mechanisms, human exposure, and the reproducibility of gas chromatography-mass spectrometry (GC-MS) dust measurements. We characterized individual particles using scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM/EDS) and Raman micro-spectroscopy (RMS). Samples were screened for the presence of 3 FR constituents (bromine, phosphorous, non-salt chlorine) and 2 metal synergists (antimony and bismuth). Subsequent analyses of select samples by RMS enabled molecular identification of the FR compounds and matrix materials. The consumer products and dust samples possessed FR elemental weight percents of up to 36% and 31%, respectively. We identified 24 FR-containing particles in the dust samples and classified them into 9 types based on morphology and composition. We observed a broad range of morphologies for these FR-containing particles, suggesting FR transfer to dust via multiple mechanisms. We developed an equation to describe the heterogeneity of FR-containing particles in environmental dust samples. The number of individual FR-containing particles expected in a 1-mg dust sample with a FR concentration of 100 ppm ranged from <1 to >1000 particles. The presence of rare, high-concentration bromine particles was correlated with decabromodiphenyl ether concentrations obtained via GC-MS. When FRs are distributed heterogeneously in highly concentrated dust particles, human exposure to FRs may be characterized by high transient exposures interspersed by periods of low exposure, and GC-MS FR concentrations may exhibit large variability in replicate subsamples. Current limitations of this SEM/EDS technique include potential false negatives for volatile and chlorinated FRs and greater quantitation uncertainty for brominated FR in aluminum-rich matrices. PMID:23739093

  16. Modeling the Submillimeter Dust Continuum Emission from Nearby Low Mass Star Forming Cores

    NASA Astrophysics Data System (ADS)

    Shirley, Y. L.; Young, C. H.; Evans, N. J., II; Rawlings, J. M. C.

    2001-12-01

    Current theories of a low mass star formation predict the evolution of the density distribution, n({r}, t), temperature distribution, T({r}, t), and the velocity field ,{v}({r}, t), of the envelope of protostellar cores with time. Optically thin dust emission at submillimeter wavelengths provides a powerful diagnostic to constrain the envelope density and temperature structure. In this study, thirty-nine low mass cores were mapped with SCUBA at 850 and 450 μ m on the JCMT during sixteen nights between January 1998 and February 2000. The sources were selected from the earliest phases (pre-T Tauri) in the proposed evolutionary scheme for low mass protostars (6 Pre-protostellar Cores (PPCs), 15 Class 0, 18 Class I) with luminosities indicative of low mass star formation (Lbol < 50 Lsun) and with distances less than 450 pc. High signal-to-noise maps allowed azimuthally averaged radial profiling out to 60 arcseconds from the continuum centroid. The similarities and differences in the submillimeter continuum emission properties of the envelopes of PPCs, Class 0, and Class I sources on 103 to 104 AU scales are summarized. We have modeled the normalized radial intensity distributions and spectral energy distributions (SED) for sixteen sources from the SCUBA survey (3 PPCs, 7 Class 0, and 6 Class I) using a one dimensional radiative transfer code (Egan, Leung, & Spagna 1988) with internal heating from a central protostar (Class 0 and I objects) and external heating from the interstellar radiation field (all objects) to calculate the dust temperature distribution. Power law, Bonnor-Ebert, Shu inside-out collapse, and Plummer density distributions were tested to match the observed normalized radial profiles and observed SED simultaneously. Realistic beam profiles and chopping were used to simulate the observations. We find Bonnor-Ebert spheres with central densities of 105 to 106 cm-3 reproduce the PPC radial profiles while power law models (n(r) ~ r-p, p = 1.1 - 2

  17. Trajectory-capture cell instrumentation for measurement of dust particle mass, velocity and trajectory, and particle capture

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Tuzzolino, A. J.

    1989-01-01

    The development of the polyvinylidene fluoride (PVDF) dust detector for space missions--such as the Halley Comet Missions where the impact velocity was very high as well as for missions where the impact velocity is low was extended to include: (1) the capability for impact position determination - i.e., x,y coordinate of impact; and (2) the capability for particle velocity determination using two thin PVDF sensors spaced a given distance apart - i.e., by time-of-flight. These developments have led to space flight instrumentation for recovery-type missions, which will measure the masses (sizes), fluxes and trajectories of incoming dust particles and will capture the dust material in a form suitable for later Earth-based laboratory measurements. These laboratory measurements would determine the elemental, isotopic and mineralogical properties of the captured dust and relate these to possible sources of the dust material (i.e., comets, asteroids), using the trajectory information. The instrumentation described here has the unique advantages of providing both orbital characteristics and physical and chemical properties--as well as possible origin--of incoming dust.

  18. The X-ray dust-scattered rings of the black hole low-mass binary V404 Cyg

    NASA Astrophysics Data System (ADS)

    Vasilopoulos, G.; Petropoulou, M.

    2016-02-01

    We report on the first detection of X-ray dust-scattered rings from the Galactic low-mass X-ray binary V404 Cyg. The observation of the system with Swift/XRT on 2015 June 30 revealed the presence of five concentric ring-like structures centred at the position of V404 Cyg. Follow-up Swift/XRT observations allowed a time-dependent study of the X-ray rings. Assuming that these are the result of small-angle, single X-ray scattering by dust grains along the line of sight, we find that their angular size scales as θ ∝ √{t} in agreement with theoretical predictions. The dust grains are concentrated in five dust layers located at about 2.12, 2.05, 1.63, 1.50 and 1.18 kpc from the observer. These coincide roughly with locations of enhanced extinction as determined by infrared photometry. Assuming that the grain size distribution is described by a generalized Mathis-Rumpl-Nordsieck model, we find that the power-law index of the most distant cloud is q ˜ 4.4, while q ˜ 3.5-3.7 in all other clouds. We constrain at a 3σ level the maximum grain size of the intermediate dust layers in the range 0.16-0.20 μm and set a lower limit of ˜ 0.2 μm in the other clouds. Hints of an exponential cutoff at the angular intensity profile of the outermost X-ray ring suggest that the smallest grains have sizes 0.01 ≤ αmin ≲ 0.03 μm. Based on the relative ratios of dust column densities we find the highest dust concentration at ˜1.6 kpc. Our results indicate a gradient in the dust properties within 1 kpc from V404 Cyg.

  19. Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean.

    PubMed

    Garrison, V H; Majewski, M S; Foreman, W T; Genualdi, S A; Mohammed, A; Massey Simonich, S L

    2014-01-15

    Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9-126 ng/m(3) (mean = 25 ± 34) at source and 0.05-0.71 ng/m(3) (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1-3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses. PMID:24055669

  20. Persistent organic contaminants in Saharan dust air masses in West Africa, Cape Verde and the eastern Caribbean

    USGS Publications Warehouse

    Garrison, Virginia H.; Majewski, Michael S.; Foreman, William T.; Genualdi, Susan A.; Mohammed, Azad; Massey Simonich, Stacy L.

    2014-01-01

    Anthropogenic semivolatile organic compounds (SOCs) that persist in the environment, bioaccumulate, are toxic at low concentrations, and undergo long-range atmospheric transport (LRT) were identified and quantified in the atmosphere of a Saharan dust source region (Mali) and during Saharan dust incursions at downwind sites in the eastern Caribbean (U.S. Virgin Islands, Trinidad and Tobago) and Cape Verde. More organochlorine and organophosphate pesticides (OCPPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyl (PCB) congeners were detected in the Saharan dust region than at downwind sites. Seven of the 13 OCPPs detected occurred at all sites: chlordanes, chlorpyrifos, dacthal, dieldrin, endosulfans, hexachlorobenzene (HCB), and trifluralin. Total SOCs ranged from 1.9–126 ng/m3 (mean = 25 ± 34) at source and 0.05–0.71 ng/m3 (mean = 0.24 ± 0.18) at downwind sites during dust conditions. Most SOC concentrations were 1–3 orders of magnitude higher in source than downwind sites. A Saharan source was confirmed for sampled air masses at downwind sites based on dust particle elemental composition and rare earth ratios, atmospheric back trajectory models, and field observations. SOC concentrations were considerably below existing occupational and/or regulatory limits; however, few regulatory limits exist for these persistent organic compounds. Long-term effects of chronic exposure to low concentrations of SOCs are unknown, as are possible additive or synergistic effects of mixtures of SOCs, biologically active trace metals, and mineral dust particles transported together in Saharan dust air masses.

  1. A HERSCHEL SURVEY OF COLD DUST IN DISKS AROUND BROWN DWARFS AND LOW-MASS STARS

    SciTech Connect

    Harvey, Paul M.; Evans, Neal J. II; Henning, Thomas; Liu Yao; Wolf, Sebastian; Menard, Francois; Pinte, Christophe; Pascucci, Ilaria E-mail: nje@astro.as.utexas.edu E-mail: wolf@astrophysik.uni-kiel.de E-mail: yliu@pmo.ac.cn E-mail: christophe.pinte@obs.ujf-grenoble.fr E-mail: pascucci@lpl.arizona.edu

    2012-08-10

    We report the complete photometric results from our Herschel study which is the first comprehensive program to search for far-infrared emission from cold dust around young brown dwarfs (BDs). We surveyed 50 fields containing 51 known or suspected BDs and very low mass stars that have evidence of circumstellar disks based on Spitzer photometry and/or spectroscopy. The objects with known spectral types range from M3 to M9.5. Four of the candidates were subsequently identified as extragalactic objects. Of the remaining 47 we have successfully detected 36 at 70 {mu}m and 14 at 160 {mu}m with signal-to-noise ratio (S/N) greater than 3, as well as several additional possible detections with low S/N. The objects exhibit a range of [24]-[70] {mu}m colors suggesting a range in mass and/or structure of the outer disk. We present modeling of the spectral energy distributions of the sample and discuss trends visible in the data. Using two Monte Carlo radiative transfer codes we investigate disk masses and geometry. We find a very wide range in modeled total disk masses from less than 10{sup -6} M{sub Sun} up to 10{sup -3} M{sub Sun} with a median disk mass of the order of 3 Multiplication-Sign 10{sup -5} M{sub Sun }, suggesting that the median ratio of disk mass to central object mass may be lower than for T Tauri stars. The disk scale heights and flaring angles, however, cover a range consistent with those seen around T Tauri stars. The host clouds in which the young BDs and low-mass stars are located span a range in estimated age from {approx}1-3 Myr to {approx}10 Myr and represent a variety of star-forming environments. No obvious dependence on cloud location or age is seen in the disk properties, though the statistical significance of this conclusion is not strong.

  2. Profiling of fine and coarse particle mass: case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes

    NASA Astrophysics Data System (ADS)

    Ansmann, A.; Seifert, P.; Tesche, M.; Wandinger, U.

    2012-10-01

    The polarization lidar photometer networking (POLIPHON) method introduced to separate coarse-mode and fine-mode particle properties of Eyjafjallajökull volcanic aerosols in 2010 is extended to cover Saharan dust events as well. Furthermore, new volcanic dust observations performed after the Grimsvötn volcanic eruptions in 2011 are presented. The retrieval of particle mass concentrations requires mass-specific extinction coefficients. Therefore, a review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is given. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

  3. Interactions of Dust Grains with Coronal Mass Ejections and Solar Cycle Variations of the F-Coronal Brightness

    NASA Technical Reports Server (NTRS)

    Ragot, B. R.; Kahler, S. W.

    2003-01-01

    The density of interplanetary dust increases sunward to reach its maximum in the F corona, where its scattered white-light emission dominates that of the electron K corona above about 3 Solar Radius. The dust will interact with both the particles and fields of antisunward propagating coronal mass ejections (CMEs). To understand the effects of the CME/dust interactions we consider the dominant forces, with and without CMEs. acting on the dust in the 3-5 Solar Radius region. Dust grain orbits are then computed to compare the drift rates from 5 to 3 Solar Radius. for periods of minimum and maximum solar activity, where a simple CME model is adopted to distinguish between the two periods. The ion-drag force, even in the quiet solar wind, reduces the drift time by a significant factor from its value estimated with the Poynting-Robertson drag force alone. The ion-drag effects of CMEs result in even shorter drift times of the large (greater than or approx. 3 microns) dust grains. hence faster depletion rates and lower dust-pain densities, at solar maxima. If dominated by thermal emission, the near-infrared brightness will thus display solar cycle variations close to the dust plane of symmetry. While trapping the smallest of the grains, the CME magnetic fields also scatter the grains of intermediate size (0.1-3 microns) in latitude. If light scattering by small grains close to the Sun dominates the optical brightness. the scattering by the CME magnetic fields will result in a solar cycle variation of the optical brightness distribution not exceeding 100% at high latitudes, with a higher isotropy reached at solar maxima. A good degree of latitudinal isotropy is already reached at low solar activity since the magnetic fields of the quiet solar wind so close to the Sun are able to scatter the small (less than or approx. 3 microns) grains up to the polar regions in only a few days or less, producing strong perturbations of their trajectories in less than half their orbital

  4. Chemical compositions and radiative properties of dust and anthropogenic air masses study in Taipei Basin, Taiwan, during spring of 2004

    NASA Astrophysics Data System (ADS)

    Chang, Shih-Yu; Fang, Guor-Cheng; Chou, Charles C.-K.; Chen, Wei-Nai

    Asia is one of the major sources of not only mineral dust but also anthropogenic aerosols. Continental air masses associated with the East Asian winter monsoon always contain high contents of mineral dust and anthropogenic species and transported southeastward to Taiwan, which have significant influences on global atmospheric radiation transfer directly by scattering and absorbing solar radiation in each spring. However, few measurements for the long-range transported aerosol and its optical properties were announced in this area, between the Western Pacific and the southeastern coast of Mainland China. The overall objective of this work is to quantify the optical characteristics of different aerosol types in the Eastern Asian. In order to achieve this objective, meteorological parameters, concentrations of PM 10 and its soluble species, and optical property of atmospheric scattering coefficients were measured continuously with 1 h time-resolved from 11 February to 7 April 2004 in Taipei Basin (25°00'N, 121°32'E). In this work, the dramatic changes of meteorological parameters such as temperature and winds were used to determine the influenced period of each air mass. Continental, strong continental, marine, and stagnant air masses defined by the back-trajectory analysis and local meteorology were further characterized as long-range transport pollution, dust, clean marine, and local pollution aerosols, respectively, according to the diagnostic ratios. The aerosol mass scattering efficiency of continental pollution, dust, clean marine, and local pollution aerosols were ranged from 1.3 to 1.6, 0.7 to 1.0, 1.4 and 1.4 to 2.3 m 2 g -1, respectively. Overall, there are two distinct populations of aerosol mass scattering efficiencies, one for an aerosol chemical composition dominated by dust (<1.0 m 2 g -1) and the other for an aerosol chemical composition dominated by anthropogenic pollutants (1.3-2.3 m 2 g -1), which were similar to the previous measurements with

  5. Measurement of the sizes of circumstellar dust shells around evolved stars with high mass loss rates

    NASA Technical Reports Server (NTRS)

    Phillips, T. G.; Knapp, G. R.

    1992-01-01

    The research supported by the NASA ADP contract NAG5-1153 has been completed. The attached paper, which will be submitted for publication in the Astrophysical Journal in January 1992, presents the results of this work. Here is a summary of the project and its results. A set of computer programs was developed to process the raw 60 micron and 100 micron IRAS survey data. The programs were designed to detect faint extended emission surrounding a bright unresolved source. Candidate objects were chosen from a list of red giant stars and young planetary nebulae which have been detected in millimeter/submillimeter lines of CO. Of the 279 stars examined, 55 were resolved at 60 microns. The principle results of the study are given. The average age for the shells surrounding the 9 Mira-type stars which are extended is 6 x 10(exp 4) yr. This suggests that the period during which these stars lose mass lasts for approx 10(exp 5) yr. The oldest shell found surrounds U Ori, and the youngest surrounds Mira itself. Some shells appear to be detached from the central star. This phenomenon is more common among older stars, suggesting that the mass loss becomes more episodic as the star sheds its envelope. Although all 8 stars less distant than 200 pc are resolved in the IRAS 60 micron data, 29 stars within 500 pc were not. These stars probably have younger circumstellar shells than those which were resolved. Almost all the carbon stars with distances of 500 pc or less have resolved shells, while only 1/2 of the oxygen-rich stars do. The resolved carbon star shells also are older on average than the oxygen-rich ones. These facts imply that carbon stars have been losing mass for a longer period, on average, than oxygen-rich red giants. Large circumstellar shells tend to be found at large distances from the galactic plane, confirming that the ISM density limits the size to which a dust shell can grow. Surprisingly, even very large shells seem to be nearly spherical, and do not appear to

  6. Lunar Surface Charging and Dust Transport during the Passage of a Coronal Mass Ejection

    NASA Astrophysics Data System (ADS)

    Stubbs, T. J.; Farrell, W. M.; Zimmerman, M. I.; Collier, M. R.; Glenar, D. A.; Halekas, J. S.

    2012-12-01

    The surface of the Moon is directly exposed to the surrounding space plasma and energetic particle (> 10 keV) populations, as well as solar ultraviolet and soft X-ray radiation on the dayside, which result in it becoming electrically charged. Under certain conditions it is possible that the resulting near-surface electric fields could have a significant influence on the transport of charged lunar dust (< ~10 microns in radius). These processes are anticipated to be most extreme at various periods during the passage of a coronal mass ejection (CME). Such an event is studied here using solar wind observations from April/May 1998 as part of the Solar Storm-Lunar Atmosphere Modeling (SSLAM) Lunar Extreme Workshop (LEW) to investigate the entire lunar surface-exosphere-space plasma system during a space weather event at the Moon. This workshop was organized by the NASA Lunar Science Institute (NLSI) Dynamic Response of the Environment At the Moon (DREAM) team. In this study, surface charging models are used to predict surface potentials and electric fields during the April/May 1998 CME event, as well as assess the importance of the different current sources and the implications for electrostatic dust transport. As expected, at the subsolar point it is found that surface charging is dominated by photoemission currents, although secondary electron emission due to plasma electrons can often have a noticeable influence. Meanwhile at the terminator, surface charging is dominated by plasma electrons and the associated secondary electron emission. At certain times the secondary electron emission is predicted to be sufficiently intense to be able to charge the shadowed surface positive. In addition, it is found that intervals with high fluxes of particles with energies > 10 keV could be very important when their current contribution exceeds that of the plasma ions. The location of the transition from positive to negative surface charging on the lunar dayside, also referred to

  7. Detection of graphite using laser microprobe mass analysis of a transbronchial biopsy from a foundry worker with mixed dust pneumoconiosis.

    PubMed

    Domej, Wolfgang; Földes-Papp, Zeno; Schlagenhaufen, Claudia; Wippel, Ruediger; Tilz, Gernot Peter; Krachler, Michael; Demel, Ulrike; Lang, Johanna; Urban-Woltron, Hildegard

    2002-03-28

    Inhalation of dust containing graphite can cause lung disease in foundry workers and workers in graphite mines or mills. Mixed dust pneumoconiosis caused by long-term occupational exposure to graphite dust is a rare disease. Only a few cases of graphite pneumoconiosis have been reported in literature, and these were usually diagnosed post mortem. Our report is of an 80-year-old male patient who had worked in an iron foundry for 20 years and whose work had entailed regular contact with ground graphite and foundry vapors. Chest x-rays revealed both a reticular and nodular pattern in the lung, moderate apical distractions and pleural scarring, all of which were confirmed by high-resolution computed tomography. Bronchoalveolar lavage and transbronchial biopsies were also consistent with mixed dust pneumoconiosis, and due to the long-term dust exposure, graphite pneumoconiosis was strongly suspected. To confirm this diagnosis, the chemical composition of the dark granules in the semi-thin histological sections of the transbronchial biopsies were analyzed using laser microprobe mass spectroscopy. The mass spectra of these black particles were consistent with those of natural graphite powder. Comparative analyses of normal lung tissue did not produce similar spectral patterns. We conclude that histology and cytology does not always suffice to confirm a diagnosis of graphite pneumoconiosis, because black particles are also found in conditions resulting from other exposures, such as heavy smoking or coal mining. Analysis of the composition of particles deposited in the lung tissue offers more precise information, which can be used as evidence in occupational and forensic medicine. Laser microprobe mass spectroscopy can assess the mineral dust load in lung samples. PMID:12238312

  8. Dust fertilization of biological productivity in the Subarctic North Pacific during the last 150 kyr

    NASA Astrophysics Data System (ADS)

    Serno, S.; Winckler, G.; Anderson, R. F.; Ren, H. A.; Hayes, C.; Machalett, B.; Gersonde, R.; Haug, G. H.

    2012-12-01

    The Subarctic North Pacific (SNP) is one of three principal High Nutrient Low Chlorophyll regions of the modern ocean characterized by an excess pool of macronutrients not completely consumed during the annual biogeochemical cycle. In the last 25 years, a number of studies from the SNP have proposed that eolian dust input of iron from East Asian arid regions is the major limiting factor for primary and export production. In recent years, additional iron sources have been suggested for regulating phytoplankton growth in the SNP, including mobilized continental margin material, ice-rafted debris, volcanic material, turbulent mixing and upwelling. We will present results of a multi-proxy approach from INOPEX core SO202-7-6 and ODP site 882 from the Detroit Seamount in the northwest SNP covering the last 30 and 150 kyr, respectively. We will compare 230Th-normalized dust flux records based on 4He, 232Th and REE, grain size distributions and 230Th-normalized fluxes of opal, total organic carbon, carbonate and biogenic barium and Pa/Th ratios as productivity proxies for INOPEX core SO202-7-6. A new high resolution record of dust fluxes based on 4He will be compared with published productivity proxy records from ODP site 882. A spatial survey of core-top sediments covering the whole SNP indicates that the efficiency of diatom export out of the euphotic zone, as defined by the ratio of opal flux in the core-top sediments to the maximum annual surface water silicate concentration during the winter months, is positively correlated with dust fluxes, possibly as a result of either dust fertilization of primary production or a diatom ballasting effect by dust particles. Preliminary results from INOPEX core SO202-7-6, on the other hand, indicate no correlation between dust flux and biological productivity during the last deglaciation. We will discuss possible explanations for these observations to answer the question if the dust fertilization hypothesis proposed by John Martin

  9. Dust and Pollution Aerosol Air Mass Mapping from Satellite Multi-angle Imaging

    NASA Astrophysics Data System (ADS)

    Kahn, R. A.; Nelson, D. L.; Yau, K. S.; Martonchik, J.; Diner, D. J.; Gaitley, B. J.; Russell, P.; Livingston, J.; Redemann, J.; Quinn, P. R.; Clarke, A. R.; Howell, S.; McNaughton, C.; Reid, J.; Holben, B.; Wendisch, M.; Petzold, A.

    2006-12-01

    One objective of the NASA Earth Observing System's Multi-angle Imaging SpectroRadiometer (MISR) is to map aerosol air mass types, based on retrieved column-average particle microphysical properties. Early results demonstrated the ability to distinguish three-to-five bins over the 0.1 to 2.5 micron aerosol size range, about two-to-four groupings of single-scattering albedo, and to separate spherical from randomly oriented non- spherical particles, under good but not ideal viewing conditions. These results relied heavily on the MISR Research Aerosol Retrieval algorithm, which allows flexibility in choosing retrieval patch size and location, component aerosol properties and mixtures, and mixture acceptance criteria, compared to early versions of the MISR Standard algorithm, designed to routinely process the entire global data set. Early mid-visible column aerosol optical depth results were validated against surface-based sun photometer measurements. The corresponding particle property results appeared qualitatively promising, but formal validation requires quantitative constraints on component particle properties and mixtures in a range of natural settings, available mainly from the combination of height-resolved and total column data collected by surface and airborne instruments during field campaigns. This presentation will highlight the latest detailed, multi-platform case studies, as well as MISR regional mapping, of smoke, Saharan dust, and mixtures of pollution aerosol and desert dust collected during the INTEX, SAMUM, and UAE-2 campaigns, respectively. The broader implications of these results for global, and especially regional, aerosol climate and air quality studies will also be discussed. This work is performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  10. Millimeter continuum measurements of circumstellar dust around very young low-mass stars

    NASA Technical Reports Server (NTRS)

    Terebey, S.; Chandler, C. J.; Andre, P.

    1994-01-01

    We investigate the question of disk formation during the protostar phase. We build on the results of Keene and Masson (1990) whose analysis of L1551 showed the millimeter continuum emission comes from both an unresolved circumstellar component, i.e., a disk and an extended cloud core. We model the dust continuum emission from the cloud core and show how it is important at 1.3 mm but negligible at 2.7 mm. Combining new 2.7 mm Owens Valley Interferometer data of IRAS-Dense cores with data from the literature we conclude that massive disks are also seen toward a number of other sources. However, 1.3 mm data from the IRAM 30 m telescope for a larger sample shows that massive disks are relatively rare, occurring around perhaps 5% of young embedded stars. This implies that either massive disks occur briefly during the embedded phase or that relatively few young stars form massive disks. At 1.3 mm the median flux of IRAS-Dense cores is nearly the same as T Tauri stars in the sample of Beckwith et al. (1990). We conclude that the typical disk mass during the embedded phase is nearly the same or less than the typical disk mass during the T Tauri phase.

  11. Efficacy of Dinotefuran (Alpine® spray and dust) on six species of stored product insects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dinotefuran, an agonist of insect nicotinic acetylcholine receptors, was evaluated both as a 0.5% active ingredient aerosol spray and a dust combined with diatomaceous earth (DE), 5 g/m2 and 10g/m2), at 45% r.h. and 75% r.h. Target species were six adult stored product insect species: Tribolium cast...

  12. Steel: Energy-Efficient Arc Furnace Dust into Saleable Chemical Products

    SciTech Connect

    Ericksen, E.

    1999-01-29

    Drinkard Metalox, Inc., has developed an innovative new technology to completely process electric arc furnace dust into saleable products by means of a hydro metallurgical process. Order this fact sheet to read how this new technology can both lower energy costs and eliminate the need to dispose of and transport hazardous waste off site.

  13. MITOCHONDRIAL OXIDANT PRODUCTION BY POLLUTANT DUST AND NO-MEDIATED APOPTOSIS IN HUMAN ALVEOLAR MACHROPHAGE

    EPA Science Inventory

    Residual oil fly ash (ROFA) is a pollutant dust that stimulates production of reactive oxygen species (ROS) from mitochondria and apoptosis in alveolar macrophages (AM), but the relationship between these two processes is unclear. In this study, human AM were incubated with RO...

  14. Production of densely sintered periclase clinker from the product of the chemical beneficiation of caustic magnesite dust

    SciTech Connect

    Simonov, K.V.

    1986-11-01

    A dense clinker with a concentration of 99% MgO has been obtained from the product of the chemical beneficiation of caustic magnesite dust cleaned out from the waste gas of rotary furnaces during the firing of magnesite. The production process includes the calcination of the product of chemical beneficiation (Mg(OH)/sub 2/), the hot dry briquetting of the MgO without binder, and firing of the hot briquette with comparatively low pressing pressure and firing temperature.

  15. On the relationship between visual magnitudes and gas and dust production rates in target comets to space missions

    NASA Astrophysics Data System (ADS)

    de Almeida, A.; Sanzovo, G.; Singh, P.; Misra, A.; Torres, R. Miguel; Boice, D.; Huebner, W.

    at frequent intervals and published periodically in International Comet Quartely (ICQ). We use the semi -classical photometric model, described in details by Newburn (1981) and de Almeida, Singh &Huebner (1997) which with some modifications introduced by us, allowed the determination of the gas production rates from observed visual magnitudes measurements, mainly for short period comets (P < 20 years). These water release rates are then used in the determination of the total surface active areas, lower limits of nuclear radii estimates, when the whole sunlit hemisphere is active, and gas mass loss rates. Also we make a systematic and uniform analysis of continuum fluxes observed at optical wavelengths, with the purpose to study the behaviour of the dust. For this, we use the framework of the photometric model of dust particles developed by Newburn &Spinrad (1985, 1989), with contributions given by de Freitas Pacheco, Landaberrry &Singh (1988) and, more recently, by Sanzovo, Singh &Huebner (1996), Singh et al. (1997) and Sanzovo et al. (2001, 2002). This way, we determine the dust release rates and evaluate the effective dust particle sizes as well as their variations with heliocentric distance. Another important result from the above photometric models is the dust-to-gas mass ratio and its behaviour with the heliocentric distance. Whenever possible, the variations of dust release rates with the heliocentric distance were compared with the quantity AFRHO (in cm), defined as the product between the albedo of the dust particles, the fraction of the aperture filled by the dust, and the radius of the slit aperture projected on the comet. This parameter was introduced by A'Hearn et al. (1984) and is frequently used, since a gas release rate divided by AFRHO give essentially, the gas-to-dust ratio. In summary, in this oral communication we report the results of a cometary research, developed during the last 10 years by our group, involving a criterious analysis of gas and

  16. Characterization of alveolar macrophage eicosanoid production in a non-human primate model of mineral dust exposure.

    PubMed

    Kuhn, D C; Griffith, J W; Stauffer, J L; Riling, S; Demers, L M

    1993-09-01

    The relative activation of eicosanoid production which results from the exposure of the alveolar macrophage (AM) to mineral dusts is thought to be a key factor in the pathophysiology of occupational lung disease. We compared in vitro basal and silica-stimulated production of prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) by AM from normal humans and non-human primates (Macaca nemestrina). In addition, we instilled mineral dusts directly into one lung of the non-human primate and evaluated AM eicosanoid production at two week intervals following dust instillation. Unstimulated AM from humans produce more PGE2 and TXA2 than do AM from M. nemestrina. However, in vitro exposure of AM from both species to silica dust produced a qualitatively similar increase in TXA2 production accompanied by no change in PGE2 production. Sequential analysis of AM eicosanoid production following a single bolus exposure to bituminous or anthracite coal dusts, titanium dioxide (TiO2) dust or crystalline silica showed marked variability among individual non-human primates in qualitative and quantitative aspects of dust-induced eicosanoid production. However, the rank order of potency of the different dusts (silica > anthracite > bituminous) correlated with epidemiological evidence relating the type of dust mined to the incidence of pneumoconiosis. These studies suggest that the non-human primate may serve as a model for the study of both the role of eicosanoids in the etiology of dust-induced occupational lung disease and the biochemical basis for individual variability in the response of lung cells to mineral dust exposure. PMID:8234829

  17. Production, partial purification and characterization of xylanase using Nicotiana tabacum leaf dust as substrate.

    PubMed

    Acharya, Komal P; Shilpkar, Prateek

    2016-03-01

    Isolated Bacillus sp. was used in the present study for production of xylanase from Nicotiana tabacum leaf dust. The strain was able to give a maximum of 1.77 Uml⁻¹ xylanase activity under optimized fermentation conditions which was further increased upto 2.77 Uml⁻¹ after extraction and partial purification of enzyme. After partial purification, the enzyme was characterized and it gave the highest xylanase activity at pH 7.0, when 0.2 ml enzyme was incubated with 2.0% substrate (Nicotiana tabacum leaf dust) for 60 min at 60°C. Saccharification study of Nicotiana tabacum leaf dust with partially purified enzyme revealed that 18.4% reducing sugar was released in 20 hrs incubation, and TLC and HPTLC analysis showed that xylose and glucose sugars were obtained after hydrolysis of substrate. FTIR analysis confirmed decomposition of substrate. PMID:27097451

  18. Modeling the total dust production of Enceladus from stochastic charge equilibrium and simulations

    NASA Astrophysics Data System (ADS)

    Meier, Patrick; Motschmann, Uwe; Schmidt, Jürgen; Spahn, Frank; Hill, Thomas W.; Dong, Yaxue; Jones, Geraint H.; Kriegel, Hendrik

    2015-12-01

    Negatively and positively charged nano-sized ice grains were detected in the Enceladus plume by the Cassini Plasma Spectrometer (CAPS). However, no data for uncharged grains, and thus for the total amount of dust, are available. In this paper we estimate this population of uncharged grains based on a model of stochastic charging in thermodynamic equilibrium and on the assumption of quasi-neutrality in the plasma-dust system. This estimation is improved upon by combining simulations of the dust component of the plume and simulations for the plasma environment into one self-consistent model. Calibration of this model with CAPS data provides a total dust production rate of about 12 kg s-1, including larger dust grains up to a few microns in size. We find that the fraction of charged grains dominates over that of the uncharged grains. Moreover, our model reproduces densities of both negatively and positively charged nanograins measured by Cassini CAPS. In Enceladus' plume ion densities up to ~104cm-3 are required by the self-consistent model, resulting in an electron depletion of about 50% in the plasma, because electrons are attached to the negatively charged nanograins. These ion densities correspond to effective ionization rates of about 10-7s-1, which are about two orders of magnitude higher than expected.

  19. RPC Production at General Tecnica: a mass scale production

    NASA Astrophysics Data System (ADS)

    della Volpe, D.; Morganti, S.

    2006-08-01

    The construction of LHC has deeply changed the RPC production. The enormous amount of detector needed and the strong requirements on gas volume quality had a deep impact on the production chain and on the QC and QA at the production site. This basically has brought the RPC from an almost hand-crafted detector to a medium scale mass product. The most critical aspects of the production chain have been modified and/or improved introducing new and more rigorous QC and QA procedures to guarantee the detector quality and improve the management of storage and the procurement on materials. Here it will be presented the work carried on in the last four year at the production site to improve and check the quality and the results achieved. Something like 10000 RPC were produced between 2002 and 2005. Also a preliminary and rough analysis on the efficiencies of the various phases in the chain production based on ATLAS production will be presented.

  20. Mobilization of dust and exfoliation of erosion product films in tokamaks

    SciTech Connect

    Martynenko, Yu. V.; Nagel, M. Yu.

    2012-04-15

    The mobilization of dust (i.e., detachment and removal of dust grains from a substrate) and the exfoliation of a film of erosion products in tokamaks have been studied theoretically. The following mechanisms of dust mobilization have been taken into account: (i) sharp heating (thermal shock) as a result of, e.g., plasma disruption and edge instabilities; (ii) substrate vibrations; and (iii) gas and plasma flow (wind) action. The most effective mobilization takes place under the action of sharp heating. Power fluxes that are characteristic of edge instabilities can mobilize dust grains with dimensions within or even greater than 0.1-1 {mu}m. The velocities of detached grains reach {nu} {approx} 100 m/s for heavy grains and up to {nu} {approx} 300 m/s for the light ones. Conditions favoring the exfoliation of a film of erosion products are determined. It is shown that exfoliation under the action of edge instabilities can take place at a film thickness of h > 1 {mu}m. Under the action of thermal-shock-induced stresses, the exfoliated film flakes with a size ranging from fractions of a millimeter to several centimeters break into pieces.

  1. CN Zeeman and dust polarization in a high-mass cold clump

    NASA Astrophysics Data System (ADS)

    Pillai, T.; Kauffmann, J.; Wiesemeyer, H.; Menten, K. M.

    2016-06-01

    We report on the young massive clump (G35.20w) in W48 that previous molecular line and dust observations have revealed to be in the very early stages of star formation. Based on virial analysis, we find that a strong field of 1640 μG is required to keep the clump in pressure equilibrium. We performed a deep Zeeman effect measurement of the 113 GHz CN (1-0) line towards this clump with the IRAM 30 m telescope. We combine simultaneous fitting of all CN hyperfines with Monte Carlo simulations for a large range in realization of the magnetic field to obtain a constraint on the line-of-sight field strength of -687 ± 420 μG. We also analyze archival dust polarization observations towards G35.20w. A strong magnetic field is implied by the remarkably ordered field orientation that is perpendicular to the longest axis of the clump. Based on this, we also estimate the plane-of-sky component of the magnetic field to be ~740 μG. This allows for a unique comparison of the two orthogonal measurements of magnetic field strength of the same region and at similar spatial scales. The expected total field strength shows no significant conflict between the observed field and that required for pressure equilibrium. By producing a probability distribution for a large range in field geometries, we show that plane-of-sky projections are much closer to the true field strengths than line-of-sight projections. This can present a significant challenge for Zeeman measurements of magnetized structures, even with ALMA. We also show that CN molecule does not suffer from depletion on the observed scales in the predominantly cold and highly deuterated core in an early stage of high-mass star formation and is thus a good tracer of the dense gas. Based on observations carried out with the IRAM 30 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  2. Profiling of fine and coarse particle mass: case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes

    NASA Astrophysics Data System (ADS)

    Ansmann, A.; Seifert, P.; Tesche, M.; Wandinger, U.

    2012-05-01

    The lidar-photometer method introduced to separate volcanic coarse-mode and fine-mode particle properties is extended to cover Saharan dust events as well. A review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is presented. These mass-specific extinction coefficients are required in the retrieval of particle mass concentration profiles. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to Central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajökull eruptions in 2010 and (d) the Grimsvötn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic events.

  3. From dust to dust: ethical and practical issues involved in the location, exhumation, and identification of bodies from mass graves.

    PubMed

    Williams, Erin D; Crews, John D

    2003-06-01

    There are many potential purposes served by the investigation of human remains: criminal fact-finding, archaeological exploration, forensic research, and others. This paper focuses on the identification of remains from mass graves to find missing persons. The primary goal of such efforts is to honor the memory of the dead by bringing closure to living family members, thus supporting the human rights of both the living and the deceased. Cultures, customs, political, and interpersonal specifics will vary, but that singular goal should remain the central guiding principle. This article presents ethical and practical issues resulting from efforts to locate, exhume, and identify the remains of mass fatalities. PMID:12808715

  4. Typology of dust particles collected by the COSIMA mass spectrometer in the inner coma of 67P/Churyumov Gerasimenko

    NASA Astrophysics Data System (ADS)

    Langevin, Y.; Hilchenbach, M.; Ligier, N.; Merouane, S.; Hornung, K.; Engrand, C.; Schulz, R.; Kissel, J.; Rynö, J.; Eng, P.

    2016-06-01

    The COSIMA mass spectrometer on board the ROSETTA orbiter has collected dust in the near coma of comet 67P/Churyumov-Gerasimenko since August 11, 2014. The collected dust particles are identified by taking images with a microscope (COSISCOPE) under grazing incidence illumination before and after exposure of the target to cometary dust. More than 10,000 dust particles >14 μm in size collected from August 11, 2014 to April 3, 2015 have been detected on three distinct target assemblies, including ˜500 dust particles with sizes ranging from 50 to more than 500 μm, that can be resolved by COSISCOPE (pixel size 14 μm). During this period, the heliocentric distance decreased from 3.5 AU to less than 2 AU. The collection efficiency on targets covered with "metal black" has been very high, due to the low relative velocity of incoming dust. Therefore, the COSISCOPE observations provide the first optical characterization of an unbiased sample of particles collected in the inner coma of a comet. The typology of particles >100 μm in size is dominated by clusters with a wide range of structure and strength, most originating from the disruption of large aggregates (>1 mm in size) shortly before collection. A generic relationship between these clusters and IDPs/Antarctic meteorites is likely in the framework of accretion models. About 15% of particles larger than 100 μm are compact particles with two likely contributions, one being linked to clusters and another leaving the cometary nucleus as single compact particles.

  5. Techniques For Mass Production Of Tunneling Electrodes

    NASA Technical Reports Server (NTRS)

    Kenny, Thomas W.; Podosek, Judith A.; Reynolds, Joseph K.; Rockstad, Howard K.; Vote, Erika C.; Kaiser, William J.

    1993-01-01

    Techniques for mass production of tunneling electrodes developed from silicon-micromachining, lithographic patterning, and related microfabrication processes. Tunneling electrodes named because electrons travel between them by quantum-mechanical tunneling; tunneling electrodes integral parts of tunneling transducer/sensors, which act in conjunction with feedback circuitry to stabilize tunneling currents by maintaining electrode separations of order of 10 Angstrom. Essential parts of scanning tunneling microscopes and related instruments, and used as force and position transducers in novel microscopic accelerometers and infrared detectors.

  6. The evolution of interstellar medium mass probed by dust emission: Alma observations at z = 0.3-2

    SciTech Connect

    Scoville, N.; Manohar, S.; Aussel, H.; Sheth, K.; Scott, K. S.; Sanders, D.; Ivison, R.; Pope, A.; Capak, P.; Vanden Bout, P.; Kartaltepe, J.; Robertson, B.; Lilly, S.

    2014-03-10

    The use of submillimeter dust continuum emission to probe the mass of interstellar dust and gas in galaxies is empirically calibrated using samples of local star-forming galaxies, Planck observations of the Milky Way, and high-redshift submillimeter galaxies. All of these objects suggest a similar calibration, strongly supporting the view that the Rayleigh-Jeans tail of the dust emission can be used as an accurate and very fast probe of the interstellar medium (ISM) in galaxies. We present ALMA Cycle 0 observations of the Band 7 (350 GHz) dust emission in 107 galaxies from z = 0.2 to 2.5. Three samples of galaxies with a total of 101 galaxies were stellar-mass-selected from COSMOS to have M {sub *} ≅ 10{sup 11} M {sub ☉}: 37 at z ∼ 0.4, 33 at z ∼ 0.9, and 31 at z = 2. A fourth sample with six infrared-luminous galaxies at z = 2 was observed for comparison with the purely mass-selected samples. From the fluxes detected in the stacked images for each sample, we find that the ISM content has decreased by a factor ∼6 from 1 to 2 × 10{sup 10} M {sub ☉} at both z = 2 and 0.9 down to ∼2 × 10{sup 9} M {sub ☉} at z = 0.4. The infrared-luminous sample at z = 2 shows a further ∼4 times increase in M {sub ISM} compared with the equivalent non-infrared-bright sample at the same redshift. The gas mass fractions are ∼2% ± 0.5%, 12% ± 3%, 14% ± 2%, and 53% ± 3% for the four subsamples (z = 0.4, 0.9, and 2 and infrared-bright galaxies).

  7. Contrasted Saharan dust events in LNLC environments: impact on nutrient dynamics and primary production

    NASA Astrophysics Data System (ADS)

    Ridame, C.; Dekaezemacker, J.; Guieu, C.; Bonnet, S.; L'Helguen, S.; Malien, F.

    2014-09-01

    The response of the phytoplanktonic community (primary production and algal biomass) to contrasted Saharan dust events (wet and dry deposition) was studied in the framework of the DUNE ("a DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem") project. We simulated realistic dust deposition events (10 g m-2) into large mesocosms (52 m3). Three distinct dust addition experiments were conducted in June 2008 (DUNE-1-P: simulation of a wet deposition; DUNE-1-Q: simulation of a dry deposition) and 2010 (DUNE-2-R1 and DUNE-2-R2: simulation of two successive wet depositions) in the northwestern oligotrophic Mediterranean Sea. No changes in primary production (PP) and chlorophyll a concentrations (Chl a) were observed after a dry deposition event, while a wet deposition event resulted in a rapid (24 h after dust addition), strong (up to 2.4-fold) and long (at least a week in duration) increase in PP and Chl a. We show that, in addition to being a source of dissolved inorganic phosphorus (DIP), simulated wet deposition events were also a significant source of nitrate (NO3-) (net increases up to +9.8 μM NO3- at 0.1 m in depth) to the nutrient-depleted surface waters, due to cloud processes and mixing with anthropogenic species such as HNO3. The dry deposition event was shown to be a negligible source of NO3-. By transiently increasing DIP and NO3- concentrations in N-P starved surface waters, wet deposition of Saharan dust was able to relieve the potential N or NP co-limitation of the phytoplanktonic activity. Due to the higher input of NO3- relative to DIP, and taking into account the stimulation of the biological activity, a wet deposition event resulted in a strong increase in the NO3-/DIP ratio, from initially less than 6, to over 150 at the end of the DUNE-2-R1 experiment, suggesting a switch from an initial N or NP co-limitation towards a severe P limitation. We also show that the contribution of new production to PP strongly increased after wet dust

  8. [Heavy metal mass accumulation of urban surface dust in Shanghai City].

    PubMed

    Chang, Jing; Liu, Min; Li, Xian-hua; Yu, Jie; Lin, Xiao; Wang, Li-li; Gao, Lei

    2008-12-01

    This paper investigated heavy metal accumulative process of road dust on paved urban surfaces of Shanghai City in April, 2006. The data indicate that the surface dust load mean value for traffic area is 12.4 g/m and the range is 5.04-23.2 g/m; the mean value for the university area is 6.1 g/m with the range of 3.8-10.0 g/m. The research indicated that long duration and high intensity rainfall has the obvious reduction function to the dust particles load, but the light rain can enable it to increase. Land use and road traffic conditions are the important factors controlling "source-sink" effect of surface dust particulate emission. Dust load buildup occurs and the particles become coarser over the dry days. In high-traffic flow area, the dust displays "source effect" on atmospheric particulate with heavy metal concentration decreasing, while in low-traffic area, the dust displays "sink effect" on atmospheric particulate with heavy metal concentration increasing. The results also show that over the dry days, with S-type growth tendency, pollutant load depends on the couple-variation of dust load and pollutant concentrations. After the rainfall, the rate of accumulation of heavy metal load remain slow within 10 days, and during the following period of 5 days, pollution load increase rapidly. Then after 15 days, the load accumulation rate of heavy metal decrease due to the equilibrium of dust deposition and emission. PMID:19256389

  9. CARBON-RICH DUST PRODUCTION IN METAL-POOR GALAXIES IN THE LOCAL GROUP

    SciTech Connect

    Sloan, G. C.; Matsuura, M.; Lagadec, E.; Van Loon, J. Th.; Kraemer, K. E.; McDonald, I.; Zijlstra, A. A.; Groenewegen, M. A. T.; Wood, P. R.; Bernard-Salas, J.

    2012-06-20

    We have observed a sample of 19 carbon stars in the Sculptor, Carina, Fornax, and Leo I dwarf spheroidal galaxies with the Infrared Spectrograph on the Spitzer Space Telescope. The spectra show significant quantities of dust around the carbon stars in Sculptor, Fornax, and Leo I, but little in Carina. Previous comparisons of carbon stars with similar pulsation properties in the Galaxy and the Magellanic Clouds revealed no evidence that metallicity affected the production of dust by carbon stars. However, the more metal-poor stars in the current sample appear to be generating less dust. These data extend two known trends to lower metallicities. In more metal-poor samples, the SiC dust emission weakens, while the acetylene absorption strengthens. The bolometric magnitudes and infrared spectral properties of the carbon stars in Fornax are consistent with metallicities more similar to carbon stars in the Magellanic Clouds than in the other dwarf spheroidals in our sample. A study of the carbon budget in these stars reinforces previous considerations that the dredge-up of sufficient quantities of carbon from the stellar cores may trigger the final superwind phase, ending a star's lifetime on the asymptotic giant branch.

  10. Dust Production of Comet 21P/Giacobini-Zinner using Broadband Photometry

    NASA Technical Reports Server (NTRS)

    Blaauw, Rhiannon C.; Suggs, Robert M.; Cooke, William J.

    2012-01-01

    Presented here are results from photometric analysis on broadband images taken of Comet 21P/Giacobini-Zinner from May 24, 2011 to October 24, 2011. As the parent body of the Draconids, a meteor shower known for outbursting, 21P was studied for its dust production activity, Afrho, focusing on how it changes with heliocentric distance. An expected increase in dust production with a decrease in heliocentric distance was observed. The comet went from heliocentric distance of 3.05 AU to 1.77 AU during the observed time that corresponded to an apparent magnitude of 19.61 to 15.72 and Afrho of 16.48 cm to 284.17 cm. These values can be extrapolated to estimate a peak Afrho value at perihelion of 3824 cm. The images were obtained using a 0.5-meter f/8.1 Ritchey-Chretien telescope located in Mayhill, New Mexico.

  11. Dust Production By Hypothetical Satellites In The Secondary Ring-moon System Of Uranus

    NASA Astrophysics Data System (ADS)

    Sfair, Rafael; Giuliatti Winter, S. M.

    2010-10-01

    The population of the ν and μ rings of Uranus is mostly composed by micrometric particles (de Pater et al, 2006), which can be strongly disturbed by the solar radiation pressure (SRP). Sfair & Giuliatti Winter (2009) showed that the combination of the SRP with the planetary oblateness and the gravitational perturbation of the closest satellites results in a series of close encounters and sometimes collisions with the small nearby satellites. When a collision occurs the probably result is the deposition of particles onto the surface of these satellites. Since this mechanism tends to cause a depletion of material of the rings, we investigate additional sources for these dust particles. Following the method presented in Krivov et al. (2002) and adopting a rough estimative of the flux of interplanetary meteoroids at Uranus' orbit, we calculated the amount of ejecta produced by hypervelocity impacts. If we assume that these collisions are effective in order to create more debris than the mass of the impactor, due to the small cross section of the satellites, the production rate is only about few grams per second. We also investigated if a supplementary amount of material can be generated by collisions of interplanetary projectiles with a population of meter-to-kilometer bodies embedded within the rings, since these bodies may provide an addition of effective cross section area to the impactors. As a preliminary analysis we analyzed a sample of hypothetical satellites located at the peak of the brightness profile of each ring. We restricted ourselves to satellites smaller than the observational threshold of 5 km. Although a sample of moonlets smaller than 5 km can survive at the ν ring without cause any perturbation in the eccentricity larger than 1E-3 of the nearby satellites, those moonlets at the μ ring disturb the orbit of Mab.

  12. Global Scale Attribution of Anthropogenic and Natural Dust Sources and their Emission Rates Based on MODIS Deep Blue Aerosol Products

    NASA Technical Reports Server (NTRS)

    Ginoux, Paul; Prospero, Joseph M.; Gill, Thomas E.; Hsu, N. Christina; Zhao, Ming

    2012-01-01

    Our understanding of the global dust cycle is limited by a dearth of information about dust sources, especially small-scale features which could account for a large fraction of global emissions. Here we present a global-scale high-resolution (0.1 deg) mapping of sources based on Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue estimates of dust optical depth in conjunction with other data sets including land use. We ascribe dust sources to natural and anthropogenic (primarily agricultural) origins, calculate their respective contributions to emissions, and extensively compare these products against literature. Natural dust sources globally account for 75% of emissions; anthropogenic sources account for 25%. North Africa accounts for 55% of global dust emissions with only 8% being anthropogenic, mostly from the Sahel. Elsewhere, anthropogenic dust emissions can be much higher (75% in Australia). Hydrologic dust sources (e.g., ephemeral water bodies) account for 31% worldwide; 15% of them are natural while 85% are anthropogenic. Globally, 20% of emissions are from vegetated surfaces, primarily desert shrublands and agricultural lands. Since anthropogenic dust sources are associated with land use and ephemeral water bodies, both in turn linked to the hydrological cycle, their emissions are affected by climate variability. Such changes in dust emissions can impact climate, air quality, and human health. Improved dust emission estimates will require a better mapping of threshold wind velocities, vegetation dynamics, and surface conditions (soil moisture and land use) especially in the sensitive regions identified here, as well as improved ability to address small-scale convective processes producing dust via cold pool (haboob) events frequent in monsoon regimes.

  13. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    ... contrast strongly with the dust storm that swept across Iraq and Saudi Arabia on May 13, 2004 (bottom panels). These data products from ... as yellowish ripples that obscure a large part of southern Iraq. The dust is easy to discern over the dark waters of the teardrop-shaped ...

  14. Impact-Mobilized Dust in the Martian Atmosphere

    NASA Technical Reports Server (NTRS)

    Nemtchinov, I. V.; Shuvalov, V. V.; Greeley, R.

    2002-01-01

    We consider dust production and entrainment into the atmosphere of Mars by impacts. Numerical simulations based on the multidimensional multimaterial hydrocode were conducted for impactors 1 to 100 m in size and velocities 11 and 20 kilometers per second. The size distribution of particles was based on experimentrr wing TNT explosions. Dust can be mobilized even when the impactor does not reach the ground through the release of energy in the atmosphere, We found that the blast produced winds entrained dust by a mechanism similar to boundary layer winds as determined from the wind-tunnel tests. For a l-m radius stony asteroid releasing its energy in the atmosphere the lifted mass of dust is larger than that in a typical dust devil and could trigger local dust storms, For a 100-m-radius meteoroid the amount of injected dust is comparable with the tota! mass of a global dust storm.

  15. Chemical weathering, mass loss, and dust inputs across a climate by time matrix in the Hawaiian Islands

    NASA Astrophysics Data System (ADS)

    Porder, Stephen; Hilley, George E.; Chadwick, Oliver A.

    2007-06-01

    We determined the total mass loss and rate of chemical weathering from three minimally eroded, Hawaiian lava flows that are ˜ 10, 170, and 350 ka old. Using a backhoe, we sampled the entire weathering zone at 28 sites and measured the depletion or enrichment of each major element in each soil horizon relative to parent material. We were able to assess the influence of both climate and substrate age on chemical weathering because each flow crosses a precipitation gradient from ˜ 600 to ˜ 2500 mm yr - 1 . Mass loss rates were highest for the 0-10 ka interval under the wettest climatic conditions (54 t km - 2 yr - 1 ), and decreased to near zero in the wet sites during the 10-170 and 170-350 ka intervals. Not surprisingly, weathering rates were lower in drier sites; ˜ 24 t km - 2 yr - 1 from 0-10 ka to < 2 t km - 2 yr - 1 thereafter. However the effects of precipitation were non-linear. There was a precipitation threshold below which mass loss was relatively small, and above which mass loss was substantial but insensitive to increased rainfall. Chemical weathering rates depend on tectonic uplift, erosion, climate, rock type or some combination thereof. By working on stable, uneroded surfaces of a single rock type across a well-constrained precipitation gradient, we were able to identify another potential driver: the rate of dust deposition. Although Hawaíi is one of the least dusty places in the northern hemisphere, dust inputs reached 82% of the total mass loss from the weathering zone at some sites, and averaged 30% on the 170 ka flow. This highlights the potential importance of dust as a component of observed weathering fluxes from catchments worldwide.

  16. Dust production and deposition in Asia and the north Pacific Ocean over the past 12 Myr

    NASA Astrophysics Data System (ADS)

    Pettke, Thomas; Halliday, Alex N.; Hall, Chris M.; Rea, David K.

    2000-05-01

    during chemical weathering but date the diagenetic growth of illite, the major K-bearing phase in the dust. Over the past 12 Myr, the dust flux to the north Pacific increased by more than an order of magnitude, documenting a substantial drying of central Asia. This climatic change, however, did not alter the ultimate source of the dust, and neoformational products of chemical weathering always remained subordinate to assemblages reworked by mechanical erosion in dust deposited in eastern Asia and the Pacific Ocean.

  17. Andromeda's dust

    SciTech Connect

    Draine, B. T.; Aniano, G.; Krause, Oliver; Groves, Brent; Sandstrom, Karin; Klaas, Ulrich; Linz, Hendrik; Rix, Hans-Walter; Schinnerer, Eva; Schmiedeke, Anika; Walter, Fabian; Braun, Robert; Leroy, Adam E-mail: ganiano@ias.u-psud.fr

    2014-01-10

    Spitzer Space Telescope and Herschel Space Observatory imaging of M31 is used, with a physical dust model, to construct maps of dust surface density, dust-to-gas ratio, starlight heating intensity, and polycyclic aromatic hydrocarbon (PAH) abundance, out to R ≈ 25 kpc. The global dust mass is M {sub d} = 5.4 × 10{sup 7} M {sub ☉}, the global dust/H mass ratio is M {sub d}/M {sub H} = 0.0081, and the global PAH abundance is (q {sub PAH}) = 0.039. The dust surface density has an inner ring at R = 5.6 kpc, a maximum at R = 11.2 kpc, and an outer ring at R ≈ 15.1 kpc. The dust/gas ratio varies from M {sub d}/M {sub H} ≈ 0.026 at the center to ∼0.0027 at R ≈ 25 kpc. From the dust/gas ratio, we estimate the interstellar medium metallicity to vary by a factor ∼10, from Z/Z {sub ☉} ≈ 3 at R = 0 to ∼0.3 at R = 25 kpc. The dust heating rate parameter (U) peaks at the center, with (U) ≈ 35, declining to (U) ≈ 0.25 at R = 20 kpc. Within the central kiloparsec, the starlight heating intensity inferred from the dust modeling is close to what is estimated from the stars in the bulge. The PAH abundance reaches a peak q {sub PAH} ≈ 0.045 at R ≈ 11.2 kpc. When allowance is made for the different spectrum of the bulge stars, q {sub PAH} for the dust in the central kiloparsec is similar to the overall value of q {sub PAH} in the disk. The silicate-graphite-PAH dust model used here is generally able to reproduce the observed dust spectral energy distribution across M31, but overpredicts 500 μm emission at R ≈ 2-6 kpc, suggesting that at R = 2-6 kpc, the dust opacity varies more steeply with frequency (with β ≈ 2.3 between 200 and 600 μm) than in the model.

  18. A semi-empirical photometric theory of cometary gas and dust production: Application to P/Halley's gas production rates

    NASA Technical Reports Server (NTRS)

    Newburn, R. L.

    1981-01-01

    The semiempirical photometric theory of cometary gas and dust production is recalibrated using UV observations from 14 comets and uniform visual photometry from 8 comets. The calibration is not changed significantly but becomes more secure. The complete theory is presented with all approximations evaluated and explained. Numerical calibration aspects are presented in tables. The theory is applied to P/Halley using a light curve without the artifact caused by the close approach to Earth in 1910. Gas production rates predicted for the 1985/86 apparition are similar to those for 1910.

  19. Computational and experimental prediction of dust production in pebble bed reactors, Part II

    SciTech Connect

    Mie Hiruta; Gannon Johnson; Maziar Rostamian; Gabriel P. Potirniche; Abderrafi M. Ougouag; Massimo Bertino; Louis Franzel; Akira Tokuhiro

    2013-10-01

    This paper is the continuation of Part I, which describes the high temperature and high pressure helium environment wear tests of graphite–graphite in frictional contact. In the present work, it has been attempted to simulate a Pebble Bed Reactor core environment as compared to Part I. The experimental apparatus, which is a custom-designed tribometer, is capable of performing wear tests at PBR relevant higher temperatures and pressures under a helium environment. This environment facilitates prediction of wear mass loss of graphite as dust particulates from the pebble bed. The experimental results of high temperature helium environment are used to anticipate the amount of wear mass produced in a pebble bed nuclear reactor.

  20. Circumstellar CO Emission in S Stars I. Mass-Loss with Little or No Dust

    NASA Technical Reports Server (NTRS)

    Sahai, R.; Liechti, S.

    1994-01-01

    47 S stars have been searched for circumstellar CO (J=1-0 and/or 2-1) emission, and 29 have been detected, including 4 which show no evidence of dust in their IRAS LRS spectra and one with possibly no Tc (and therefore not an AGB star).

  1. FIRST-2MASS RED QUASARS: TRANSITIONAL OBJECTS EMERGING FROM THE DUST

    SciTech Connect

    Glikman, Eilat; Urrutia, Tanya; Lacy, Mark; Djorgovski, S. George; Mahabal, Ashish; Myers, Adam D.; Ross, Nicholas P.; Petitjean, Patrick; Ge, Jian; Schneider, Donald P.; York, Donald G.

    2012-09-20

    We present a sample of 120 dust-reddened quasars identified by matching radio sources detected at 1.4 GHz in the Faint Images of the Radio Sky at Twenty Centimeters survey with the near-infrared Two Micron All Sky Survey catalog and color-selecting red sources. Optical and/or near-infrared spectroscopy provide broad wavelength sampling of their spectral energy distributions that we use to determine their reddening, characterized by E(B - V). We demonstrate that the reddening in these quasars is best described by Small-Magellanic-Cloud-like dust. This sample spans a wide range in redshift and reddening (0.1 {approx}< z {approx}< 3, 0.1 {approx}< E(B - V) {approx}< 1.5), which we use to investigate the possible correlation of luminosity with reddening. At every redshift, dust-reddened quasars are intrinsically the most luminous quasars. We interpret this result in the context of merger-driven quasar/galaxy co-evolution where these reddened quasars are revealing an emergent phase during which the heavily obscured quasar is shedding its cocoon of dust prior to becoming a 'normal' blue quasar. When correcting for extinction, we find that, depending on how the parent population is defined, these red quasars make up {approx}< 15%-20% of the luminous quasar population. We estimate, based on the fraction of objects in this phase, that its duration is 15%-20% as long as the unobscured, blue quasar phase.

  2. The slow flow model of dust efflux in local star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Zahid, H. J.; Torrey, P.; Kudritzki, R. P.; Kewley, L. J.; Davé, R.; Geller, M. J.

    2013-12-01

    We develop a dust efflux model of radiation pressure acting on dust grains which successfully reproduces the relation between stellar mass, dust opacity and star formation rate observed in local star-forming galaxies. The dust content of local star-forming galaxies is set by the competition between the physical processes of dust production and dust loss in our model. The dust loss rate is proportional to the dust opacity and star formation rate. Observations of the relation between stellar mass and star formation rate at several epochs imply that the majority of local star-forming galaxies are best characterized as having continuous star formation histories. Dust loss is a consequence of sustained interaction of dust with the radiation field generated by continuous star formation. Dust efflux driven by radiation pressure rather than dust destruction offers a more consistent physical interpretation of the dust loss mechanism. By comparing our model results with the observed relation between stellar mass, dust extinction and star formation rate in local star-forming galaxies, we are able to constrain the time-scale and magnitude of dust loss. The time-scale of dust loss is long and therefore dust is effluxed in a `slow flow'. Dust loss is modest in low-mass galaxies but massive galaxies may lose up to 70-80 per cent of their dust over their lifetime. Our slow flow model shows that mass-loss driven by dust opacity and star formation may be an important physical process for understanding normal star-forming galaxy evolution.

  3. An unusually very bright dust light mass (?) observed in the vicinity (?) of á Lyrae

    NASA Astrophysics Data System (ADS)

    Stefanopoulos, G.

    2009-04-01

    There are not many written worldwide references regarding unusual phenomena such as dust, unusual lights or unexplained objects orbiting the earth or the solar and extra solar systems. Regarding the external space few references exist . Regarding the a Lyrae many scientists were involve in the eighties with the possible existence of a planet next to this star. Structure in the Dusty Debris around Vega, D. J. Wilner et al 2002 ApJ 569.Near-infrared observations of Vega, at 2006 Philip M. Hinz et al. refers to possible companion planet round this star .In constellations Lyrae and Eridani,some authors refer to possible initial formation of planets and they mention the presence of dust formations orbiting around those stars.(A. N. Heinze, Philip M. Hinz, Deep L' and M-band Imaging for Planets Around Vega and epsilon Eridani,The Astrophysical Journal 688 (2008) 583. This paper is concerned with an unexplained or perhaps portion of dust, in the constellation of Lyrae, which appears and have been observed only in conventional photographic plaque.For this observation , simple equipment and amateur instruments are use.In the night of April the 2002, during an amatory observation in variable stars, in the RR Lyrae, pictures were taken in the mentioned deep space area as a normal weekly study procedure. The instruments used are, telescope Meade 10΄΄, illuminate reticle guiding, 12mm, photo camera Nikon F -100, and lenses,70mm, f =1,8.The film used was a Kodak X-pro,BW 400 ASA.The equatorial mount was motorized. A total of six pictures with an exposure 5-10 min were taken. While developing the film, on the fifth photogram, a bright (object?) - dust light appear which seems to be in adhesion with the Vega star . On consecutive months more pictures were taken, with conventional and digital exposures, without any repetition of the event. What is provoke illumination of this dust portion to have been present in a simple photographic film? This simple observation study is

  4. Potential of laser ablation and laser desorption mass spectrometry to characterize organic and inorganic environmental pollutants on dust particles.

    PubMed

    Carré, Vincent; Aubriet, Frédéric; Scheepers, Paul T; Krier, Gabriel; Muller, Jean-François

    2005-01-01

    Stainless steel factories are known to release particles into the atmosphere. Such particulate matter contains significant amounts of heavy metals or toxic inorganic compounds and organic pollutants such as, for example, Cr(VI) and polycyclic aromatic hydrocarbons (PAHs). The investigation of Cr(VI) and PAHs is often complicated by the associated matrix. Organic and inorganic pollutants present in stainless steel dust particles have been investigated with the same laser microprobe mass spectrometer according to two original methodologies. These analytical methods do not require time-consuming pretreatment (extraction, solubilization) or preconcentration steps. More specifically, experiments are conducted with a Fourier transform ion cyclotron resonance mass spectrometer coupled to an ArF (193 nm) or a tripled frequency Nd-YAG (355 nm) laser. Experiments at 355 nm allow the nature of the most frequently occurring Cr(III)/Cr(VI) compounds in dust particles to be identified. Examination of PAHs at 193 nm is assisted by the formation of pi-complexes with 7,7',8,8'-tetracyanoquinodimethane to prevent their evaporation in the mass spectrometer during analysis and to ensure an increase in sensitivity. PMID:15724235

  5. [Determination of 39 polychlorinated biphenyls in indoor dust using ultrasonic extraction and gas chromatography-tandem mass spectrometry].

    PubMed

    Wang, Bingling; Zhang, Xiaoling; Zhang, Qi; Lu, Xiaomei; Cui, Yuan; Zhang, Zhengdong

    2014-01-01

    A method for the determination of 39 polychlorinated biphenyls (PCBs) in indoor dust was developed. A vacuum cleaner was used for gathering the house dust. N-Hexane-dichloromethane (1: 1, v/v) was added and the extraction was performed in an ultrasonic bath. The supernatant was concentrated and then 0.1 mL n-hexane-dichloromethane (1: 1, v/v) was added. Gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected-reaction monitoring (SRM) mode has been investigated for the determination of the 39 PCBs congeners in indoor dust. The 39 PCBs had highly efficient separation within 30 min and showed good linearity in the range of 0.1 - 100 microg/L with the correlation coefficients of 0.991 0 - 0.999 9. The spiked recoveries were 57.2% - 120.3%. The intra-day relative standard deviations (RSDs) were between 0.3% and 24.7%, while the inter-day RSDs were between 0.6% and 29.9%. This method has good linearity, high sensitivity, high accuracy and precision. Also, it is simple, rapid and low solvent consumption. The low chemical background interference allowed it to be used in more complex matrices. PMID:24783872

  6. Dust Seds And Processing Near Sites Of High Mass Star Formation In The LMC

    NASA Astrophysics Data System (ADS)

    Hony, Sacha; Galliano, F.; Madden, S. M.; SAGE Consortium

    2010-01-01

    We present a study into the properties of the dust and complex molecules in and around selected HII regions in the Large Magellanic Cloud. The analysis is based on the Spitzer program SAGE (Surveying the Agents of a Galaxy's Evolution). Because of the lower metallicity environment, dust shielding is reduced and the effects of the ultraviolet radiation carry further than in the Milky way. Because of this these HII regions may better represent star forming regions in the more distant universe. We present the near- to far-IR spectral energy distributions (SEDs) as a function of radial distance to the center of the several clusters. The regions span a wide range in luminosities. We have developed a self consistent spherical clumpy dust radiative transfer model to interpret the observed trends. The model treats the detailed dust optical properties and transient grain heating as well as IR absorption and reprocession. This allows us to interpret the observed variations in SED in terms of the clumpiness, varying incident radiation-field and changing abundances of polycyclic aromatic hydrocarbons (PAHs), transiently heated very small grains (VSG) to submicron-sized grains in thermal equilibrium, i.e. in terms of the varying grain-size distribution. We find that the LMC massive star forming sites are typified by a several parsec sized void and clumpiness and PAH abundance which increases with distance from the central illuminating source. The inner void may be the result of massive star winds. The observed flat mid-IR SEDs require a grain-size distribution skewed to a higher fraction of smaller grains compared to the Milky Way dust.

  7. Biological/biomedical accelerator mass spectrometry targets. 1. optimizing the CO2 reduction step using zinc dust.

    PubMed

    Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

    2008-10-15

    Biological and biomedical applications of accelerator mass spectrometry (AMS) use isotope ratio mass spectrometry to quantify minute amounts of long-lived radioisotopes such as (14)C. AMS target preparation involves first the oxidation of carbon (in sample of interest) to CO 2 and second the reduction of CO 2 to filamentous, fluffy, fuzzy, or firm graphite-like substances that coat a -400-mesh spherical iron powder (-400MSIP) catalyst. Until now, the quality of AMS targets has been variable; consequently, they often failed to produce robust ion currents that are required for reliable, accurate, precise, and high-throughput AMS for biological/biomedical applications. Therefore, we described our optimized method for reduction of CO 2 to high-quality uniform AMS targets whose morphology we visualized using scanning electron microscope pictures. Key features of our optimized method were to reduce CO 2 (from a sample of interest that provided 1 mg of C) using 100 +/- 1.3 mg of Zn dust, 5 +/- 0.4 mg of -400MSIP, and a reduction temperature of 500 degrees C for 3 h. The thermodynamics of our optimized method were more favorable for production of graphite-coated iron powders (GCIP) than those of previous methods. All AMS targets from our optimized method were of 100% GCIP, the graphitization yield exceeded 90%, and delta (13)C was -17.9 +/- 0.3 per thousand. The GCIP reliably produced strong (12)C (-) currents and accurate and precise F m values. The observed F m value for oxalic acid II NIST SRM deviated from its accepted F m value of 1.3407 by only 0.0003 +/- 0.0027 (mean +/- SE, n = 32), limit of detection of (14)C was 0.04 amol, and limit of quantification was 0.07 amol, and a skilled analyst can prepare as many as 270 AMS targets per day. More information on the physical (hardness/color), morphological (SEMs), and structural (FT-IR, Raman, XRD spectra) characteristics of our AMS targets that determine accurate, precise, and high-hroughput AMS measurement are in the

  8. New Extinction and Mass Estimates of the Low-mass Companion 1RXS 1609 B with the Magellan AO System: Evidence of an Inclined Dust Disk

    NASA Astrophysics Data System (ADS)

    Wu, Ya-Lin; Close, Laird M.; Males, Jared R.; Barman, Travis S.; Morzinski, Katie M.; Follette, Katherine B.; Bailey, Vanessa P.; Rodigas, Timothy J.; Hinz, Philip; Puglisi, Alfio; Xompero, Marco; Briguglio, Runa

    2015-07-01

    We used the Magellan adaptive optics system to image the 11 Myr substellar companion 1RXS 1609 B at the bluest wavelengths to date (z‧ and Ys). Comparison with synthetic spectra yields a higher temperature than previous studies of {T}{eff}=2000+/- 100 {{K}} and significant dust extinction of {A}V={4.5}-0.7+0.5 mag. Mass estimates based on the DUSTY tracks gives 0.012-0.015 {M}⊙ , making the companion likely a low-mass brown dwarf surrounded by a dusty disk. Our study suggests that 1RXS 1609 B is one of the ˜25% of Upper Scorpius low-mass members harboring disks, and it may have formed like a star and not a planet out at ˜320 AU. This paper includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

  9. ORIGIN OF DUST AROUND V1309 SCO

    SciTech Connect

    Zhu, Chunhua; Lü, Guoliang; Wang, Zhaojun

    2013-11-01

    The origin of dust grains in the interstellar medium is still an unanswered problem. Nicholls et al. found the presence of a significant amount of dust around V1309 Sco, which may originate from the merger of a contact binary. We investigate the origin of dust around V1309 Sco and suggest that these dust grains are produced in the binary-merger ejecta. By means of the AGBDUST code, we estimate that ∼5.2 × 10{sup –4} M{sub ☉} dust grains are produced with a radii of ∼10{sup –5} cm. These dust grains are mainly composed of silicate and iron grains. Because the mass of the binary merger ejecta is very small, the contribution of dust produced by binary merger ejecta to the overall dust production in the interstellar medium is negligible. However, it is important to note that the discovery of a significant amount of dust around V1309 Sco offers a direct support for the idea that common-envelope ejecta provides an ideal environment for dust formation and growth. Therefore, we confirm that common envelope ejecta can be important source of cosmic dust.

  10. Dust ablation in Pluto's atmosphere

    NASA Astrophysics Data System (ADS)

    Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan

    2016-04-01

    Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

  11. Dust feed mechanism

    DOEpatents

    Milliman, Edward M.

    1984-01-01

    The invention is a dust feed device for delivery of a uniform supply of dust for long periods of time to an aerosolizing means for production of a dust suspension. The device utilizes at least two tandem containers having spiral brushes within the containers which transport the dust from a supply to the aerosolizer means.

  12. Mass extinctions: Ecological selectivity and primary production

    NASA Astrophysics Data System (ADS)

    Rhodes, Melissa Clark; Thayer, Charles W.

    1991-09-01

    If mass extinctions were caused by reduced primary productivity, then extinctions should be concentrated among animals with starvation-susceptible feeding modes, active lifestyles, and high-energy budgets. The stratigraphic ranges (by stage) of 424 genera of bivalves and 309 genera of articulate brachiopods suggest that there was an unusual reduction of primary productivity at the Cretaceous/Tertiary (K/T) boundary extinction. For bivalves at the K/T, there were (1) selective extinction of suspension feeders and other susceptible trophic categories relative to deposit feeders and other resistant categories, and (2) among suspension feed-ers, selective extinction of bivalves with active locomotion. During the Permian-Triassic (P/Tr) extinction and Jurassic background time, extinction rates among suspension feeders were greater for articulate brachiopods than for bivalves. But during the K/T event, extinction rates of articulates and suspension-feeding bivalves equalized, possibly because the low-energy budgets of articulates gave them an advantage when food was scarce.

  13. Gas and dust production by Comet P/Halley (1910 II)

    NASA Technical Reports Server (NTRS)

    Howell, Ellen S.; Lutz, Barry L.; Slipher, V. M.

    1991-01-01

    Selected long-slit spectrograms of Comet P/Halley, photographed during the postperihelion period between April 16 and June 3, 1910 have been quantitatively analyzed for comparison with the 1985/86 apparition. The Fe-V-Na spark spectrum was used to determine characteristic curves for these plates, and flux calibrations based on contemporaneous broad-band photometric measurements were applied. Haser model production rates for C2 and values Afp were computed for each of the nights selected and compared with the photometric observations obtained by Schleicher et al. (1987) during the comparable postperihelion period of the 1985/86 apparition. As found for the 1985/86 apparation, the gas and dust production in 1910 varied in phase, but the rates of production were higher than observed in 1986 by a small but statistically significant amount.

  14. The Motion Verified Red Stars (MoVeRS) Catalog and Low-Mass Field Stars with Warm Dust

    NASA Astrophysics Data System (ADS)

    Theissen, Christopher; West, Andrew A.; Dhital, Saurav

    2016-01-01

    We present the Motion Verified Red Stars (MoVeRS) catalog of proper motion selected low-mass stars from SDSS, 2MASS, and WISE. These surveys provide a time baseline of ~12 years for sources found in all three surveys, and a precision better than 10 mas/year.The MoVeRS catalog is augmented with proper motions from SDSS+USNO-B and the full sample contains 8,735,004 photometric point-sources selected based on colors and their significant (2σ) proper motions. This catalog will be useful for finding new low-mass common proper motion systems, along with providing a large input catalog for numerous studies of low-mass stars. In addition, we use the MoVeRS catalog to present a preliminary sample of low-mass field stars exhibiting signatures of warm dust (mid-infrared excesses). Such systems are thought to originate from collisions of terrestrial planets, raising even more questions about the habitability of planetary systems around low-mass stars.

  15. Dust Measurements in Tokamaks

    SciTech Connect

    Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M

    2008-04-23

    Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 {micro}m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

  16. DUST FORMATION IN THE EJECTA OF COMMON ENVELOPE SYSTEMS

    SciTech Connect

    Lue Guoliang; Zhu Chunhua; Podsiadlowski, Philipp

    2013-05-10

    The material that is ejected in a common-envelope (CE) phase in a close binary system provides an ideal environment for dust formation. By constructing a simple toy model to describe the evolution of the density and the temperature of CE ejecta and using the AGBDUST code to model dust formation, we show that dust can form efficiently in this environment. The actual dust masses produced in the CE ejecta depend strongly on their temperature and density evolution. We estimate the total dust masses produced by CE evolution by means of a population synthesis code and show that, compared to dust production in asymptotic giant branch stars, the dust produced in CE ejecta may be quite significant and could even dominate under certain circumstances.

  17. Dust Production of Comet 21P/Giacobini-Zinner Using Broadband Photometry

    NASA Technical Reports Server (NTRS)

    Blaauw, R. C.; Suggs, R. M.; Cooke, W.

    2012-01-01

    Comet 21P/Giacobini-Zinner is a Jupiter family comet, approximately 2 km in diameter, and is established to be the parent of the Draconids, a meteor shower known to outburst. In 1933 and 1946 up to 10,000 meteors per hour were reported for the Draconids, and 2011 saw a minor Draconid outburst. Meteor stream modeling/forecasting being a primary focus for the NASA Meteoroid Environment Office, it was decided to monitor 21P for three purposes: firstly to find the apparent and absolute magnitude with respect to heliocentric distance; second to calculate Af , a quantity that describes the dust production rate and is used in models to predict the activity of the Draconids; and thirdly to detect possible increases in cometary activity, which could correspond to future Draconid meteor outbursts. A similar study was done for 21P during its 2004-2006 close approach to the Sun in which apparent and absolute magnitudes were found with various heliocentric distances, as well as the dust production. At 2.32 AU from the Sun, 21P possessed an apparent magnitude of 17.05 and Af of 83 cm, and an apparent magnitude of 15.91 and Af of 130.66 cm at 1.76 AU from the sun.

  18. Impact of intensive dust outbreaks on marine primary production as seen by satellites

    NASA Astrophysics Data System (ADS)

    Papadimas, Christos; Hatzianastassiou, Nikos; Mihalopoulos, Nikos; Kanakidou, Maria

    2016-04-01

    The impact of intensive dust outbreaks from the African continent on the marine primary production of the Mediterranean sea is here investigated using MODIS satellite observations of atmospheric aerosol optical depth and chlorophyll-a in the seawater. Dust outbreak episodes in the area are detected based on aerosol relevant satellite observations over a 12-year period from 2003 to 2014. For a total of 167 identified episodes, correlations between aerosol optical depth and chlorophyll-a are investigated both on regional and on a pixel by pixel basis as well as for simultaneous or time-lagged satellite observations. The identified co-variations are thoroughly discussed in view of the impact of nutrient atmospheric deposition on the marine biology in the Mediterranean Sea ecosystem. This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARISTEIA - PANOPLY (Pollution Alters Natural Aerosol Composition: implications for Ocean Productivity, cLimate and air qualitY) grant.

  19. The relation between the gas, dust and total mass in edge-on spiral galaxies

    NASA Astrophysics Data System (ADS)

    Allaert, Flor

    2015-02-01

    Each component of a galaxy plays its own unique role in regulating the galaxy's evolution. In order to understand how galaxies form and evolve, it is therefore crucial to study the distribution and properties of each of the various components, and the links between them, both radially and vertically. The latter is only possible in edge-on systems. We present the HEROES project, which aims to investigate the 3D structure of the interstellar gas, dust, stars and dark matter in a sample of 7 massive early-type spiral galaxies based on a multi-wavelength data set including optical, NIR, FIR and radio data.

  20. The AKARI 2.5-5.0 μm Spectral Atlas of Type-1 Active Galactic Nuclei: Black Hole Mass Estimator, Line Ratio, and Hot Dust Temperature

    NASA Astrophysics Data System (ADS)

    Kim, Dohyeong; Im, Myungshin; Kim, Ji Hoon; Jun, Hyunsung David; Woo, Jong-Hak; Lee, Hyung Mok; Lee, Myung Gyoon; Nakagawa, Takao; Matsuhara, Hideo; Wada, Takehiko; Oyabu, Shinki; Takagi, Toshinobu; Ohyama, Youichi; Lee, Seong-Kook

    2015-01-01

    We present 2.5-5.0 μm spectra of 83 nearby (0.002 < z < 0.48) and bright (K < 14 mag) type-1 active galactic nuclei (AGNs) taken with the Infrared Camera on board AKARI. The 2.5-5.0 μm spectral region contains emission lines such as Brβ (2.63 μm), Brα (4.05 μm), and polycyclic aromatic hydrocarbons (3.3 μm), which can be used for studying the black hole (BH) masses and star formation activity in the host galaxies of AGNs. The spectral region also suffers less dust extinction than in the ultra violet (UV) or optical wavelengths, which may provide an unobscured view of dusty AGNs. Our sample is selected from bright quasar surveys of Palomar-Green and SNUQSO, and AGNs with reverberation-mapped BH masses from Peterson et al. Using 11 AGNs with reliable detection of Brackett lines, we derive the Brackett-line-based BH mass estimators. We also find that the observed Brackett line ratios can be explained with the commonly adopted physical conditions of the broad line region. Moreover, we fit the hot and warm dust components of the dust torus by adding photometric data of SDSS, 2MASS, WISE, and ISO to the AKARI spectra, finding hot and warm dust temperatures of ~1100 K and ~220 K, respectively, rather than the commonly cited hot dust temperature of 1500 K.

  1. ATL Products Division's entries into the computer mass storage marketplace

    NASA Technical Reports Server (NTRS)

    Zeiler, Fred

    1991-01-01

    The viewgraphs of a discussion on ATL Products Division's entries into the computer mass storage marketplace presented at the National Space Science Data Center (NSSDC) Mass Storage Workshop is included. Topics covered are product evolution including robotics; aperture storage module library; Broadcast Division's TCS2000 Video Cart and TCS90 Videocart System; high density systems business product lines; and storage and library management.

  2. Herschel OBSERVATIONS OF DUST AROUND THE HIGH-MASS X-RAY BINARY GX 301-2

    SciTech Connect

    Servillat, M.; Coleiro, A.; Chaty, S.; Rahoui, F.; Zurita Heras, J. A.

    2014-12-20

    We aim at characterizing the structure of the gas and dust around the high-mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant (HG) star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs from the optical to the radio range (0.4 to 4 × 10{sup 4} μm). GX 301-2 is detected for the first time at 70 and 100 μm. We fitted different models of circumstellar (CS) environments to the data. All tested models are statistically acceptable, and consistent with an HG star at ∼3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far-infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favor a disk-like CS environment of ∼8 AU that would enshroud the binary system. The temperature goes down to ∼200 K at the edge of the disk, allowing for dust formation. This disk is probably a rimmed viscous disk with an inner rim at the temperature of the dust sublimation temperature (∼1500 K). The similarities between the HG GX 301-2, B[e] supergiants, and the highly obscured X-ray binaries (particularly IGR J16318-4848) are strengthened. GX 301-2 might represent a transition stage in the evolution of massive stars in binary systems, connecting supergiant B[e] systems to luminous blue variables.

  3. Herschel Observations of Dust around the High-mass X-Ray Binary GX 301-2

    NASA Astrophysics Data System (ADS)

    Servillat, M.; Coleiro, A.; Chaty, S.; Rahoui, F.; Zurita Heras, J. A.

    2014-12-01

    We aim at characterizing the structure of the gas and dust around the high-mass X-ray binary GX 301-2, a highly obscured X-ray binary hosting a hypergiant (HG) star and a neutron star, in order to better constrain its evolution. We used Herschel PACS to observe GX 301-2 in the far infrared and completed the spectral energy distribution of the source using published data or catalogs from the optical to the radio range (0.4 to 4 × 104 μm). GX 301-2 is detected for the first time at 70 and 100 μm. We fitted different models of circumstellar (CS) environments to the data. All tested models are statistically acceptable, and consistent with an HG star at ~3 kpc. We found that the addition of a free-free emission component from the strong stellar wind is required and could dominate the far-infrared flux. Through comparisons with similar systems and discussion on the estimated model parameters, we favor a disk-like CS environment of ~8 AU that would enshroud the binary system. The temperature goes down to ~200 K at the edge of the disk, allowing for dust formation. This disk is probably a rimmed viscous disk with an inner rim at the temperature of the dust sublimation temperature (~1500 K). The similarities between the HG GX 301-2, B[e] supergiants, and the highly obscured X-ray binaries (particularly IGR J16318-4848) are strengthened. GX 301-2 might represent a transition stage in the evolution of massive stars in binary systems, connecting supergiant B[e] systems to luminous blue variables.

  4. Estimation of individual dust exposure by magnetopneumography in stainless steel production.

    PubMed

    Huvinen, M; Oksanen, L; Kalliomäki, K; Kalliomäki, P L; Moilanen, M

    1997-06-20

    The objectives of the study were to measure the magnetic dust lung burden of workers in stainless steel production by magnetopneumography (MPG) and to investigate the relationship of the results with air-borne concentrations of dust, total and hexavalent chromium as well as urinary excretion of chromium. There were 128 workers from the chromite mine, sintering plant, ferrochrome smelter, stainless steel smelting shop, cold rolling mill and welding shop in the exposed groups and five persons from the office staff in the control group. The remanent magnetic field (RMF) in the lungs was slightly elevated among workers in the ferrochromium and steel smelting shops; the levels were, however, lower than those reported for welders earlier and those observed in the welding/repair shop. Workers in the mine, concentrator and sintering plants and in the cold rolling mill exhibited remanent magnetic fields comparable to the referents. There was a relationship between the RMF and the actual urinary chromium concentration. Miners and concentrator and sintering plant workers showed retarded relaxation rate (ReR) of the remanent magnetic field. However, the RMF of the first two of these groups were low (< 0.1 nT) and this made it difficult to measure the ReR accurately. The duration of exposure correlated weakly but significantly with the relaxation rate, while smoking was not related to it. PMID:9200856

  5. Dust Production of Comet 21P/Giacobini Zinner Using Broadband Photometry

    NASA Technical Reports Server (NTRS)

    Blaauw, Rhiannon; Suggs, Robert M.; Cooke, William

    2012-01-01

    Comet 21P/Giacobini-Zinner is a Jupiter family comet that was discovered in December of 1900 by the French astronomer Michel Giacobini, and rediscovered two orbits later by German astronomer Ernst Zinner in 1913. 21P is approximately 2 km in diameter, and is the parent of the Draconids, a meteor shower known to undergo dramatic outbursts. In 1933 and 1946, up to 10,000 meteors per hour were reported for the Draconids; and 2011 saw a minor Draconid outburst. As meteor stream modeling/ forecasting is a primary focus for the NASA Meteoroid Environment Office, it was decided to monitor 21P for three purposes: firstly to find the apparent and absolute magnitude with respect to heliocentric distance; second to calculate Af(rho), a quantity that describes the dust production rate and is used in models to predict the activity of the Draconids; thirdly to detect possible increases in cometary activity, which could correspond to future Draconid meteor outbursts. Giacobini-Zinner is unique in several ways. It was the first comet to have measurements made in situ. Comet 21P was visited by ICE (International Cometary Explorer) in 1985 to study the interaction of the cometary atmosphere with the flowing solar-wind plasma. It is a carbon-depleted comet, and most studies show that it peaks in gas and dust production pre-perihelion, specifically in two very studied passages; 1985 and 1998. A prior study was conducted by Pittichova et al (2008) for 21P during its 2004-2006 close approach to the Sun. Apparent and absolute magnitudes were measured at various heliocentric distances as well as the dust production. At 2.32 AU from the Sun, 21P exhibited an apparent magnitude of 17.05 and Af of 83 cm, and an apparent magnitude of 15.91/Af(rho) of 130.66 cm at 1.76 AU. Another such study performed by Lara et al.on 21P s 1998 apparition found values of Af(rho) of 1010 cm when 1.05 AU from the Sun, two weeks before perihelion, and 669 cm at perihelion, when 1.03 AU from the Sun

  6. The Dusty Nova: An Examination of Dust Production and Processing in the Ejecta of Classical Novae

    NASA Astrophysics Data System (ADS)

    Helton, L. A.; Evans, A.; Woodward, C. E.; Gehrz, R. D.; Vacca, W.

    2014-12-01

    Classical novae (CNe) are known to frequently produce dust in their ejecta. Infrared observations have revealed that the dust produced can be of a variety of different species, including silicates, amorphous carbon, hydrocarbons, and silicon carbide. Due to their relatively rapid evolution, CNe provide unique laboratories for the examination of the processes of dust condensation, grain growth, and destruction. Here we present analysis of the near- to mid-IR spectra of a number of recent dust forming novae, including V2361 Cyg, V2362 Cyg, and V1280 Sco. We discuss the implications for our understanding of dust formation and processing with particular emphasis on the role of hydrocarbon species.

  7. Pressurized solvent extraction followed by gas chromatography tandem mass spectrometry for the determination of benzotriazole light stabilizers in indoor dust.

    PubMed

    Carpinteiro, I; Abuín, B; Rodríguez, I; Ramil, M; Cela, R

    2010-06-11

    A novel and sensitive method for the determination of five benzotriazole compounds (commonly used as light stabilizers) in indoor dust is presented. Pressurized liquid extraction (PLE) and gas chromatography followed by tandem in time mass spectrometry (GC-MS/MS) were used as sample preparation and determination techniques, respectively. Extraction and clean-up were integrated on-line and, after an evaporative concentration step, the extract provided by the PLE instrument was injected directly in the GC-MS/MS system. Parameters affecting the performance of the sample preparation process were evaluated using experimental factorial designs. Under optimized conditions, analytes were recovered from 0.5g samples in 3 static extraction cycles of 10min, using a hexane:dichloromethane (7:3) mixture, at 90 degrees C. Silica (1g) was placed in the bottom of the extraction cells as clean-up sorbent. The recoveries of the method varied from 82 to 122%, with standard deviations below 13. The inter-day precision ranged from 9 to 12%, and the limits of quantification (LOQs) remained below 10ngg(-1) for all species. For the first time, four of the five investigated species were found in dust from indoor environments. Their mean concentrations ranged from 71 to 780ngg(-1). PMID:20435314

  8. Direct observations of the atmospheric processing of Asian mineral dust

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Guazzotti, S. A.; Sodeman, D. A.; Prather, K. A.

    2006-05-01

    The accumulation of secondary acid products and ammonium on individual mineral dust particles during ACE-Asia has been measured in real-time using ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles corresponded to different air mass source regions. During volcanically influenced periods, dust mixed with sulphate dominated. This rapidly switched to dust predominantly mixed with chloride when the first Asian dust front reached the R/V Ronald Brown. We hypothesise that the high degree of mixing of dust with chloride was caused by the prior reaction of NOy(g) and volcanic SO2(g) with sea salt particles, reducing the availability of nitrate and sulphate precursors while releasing HCl(g), which then reacted with the incoming dust front. The segregation of sulphate from nitrate and chloride in individual dust particles is demonstrated for the first time. This is likely caused by the dust plume encountering elevated SO2(g) in the Chinese interior before reaching coastal urban areas polluted by both SO2(g) and NOx(g). This caused the fractions of dust mixed with nitrate and/or chloride to be strongly dependent on the total dust loadings, whereas dust mixed with sulphate did not show this same dust concentration dependence. Ammonium was also significantly mixed with dust and the amount correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent statements that they exist as an external mixture. The size distribution of the mixing state of dust with these secondary species validates previous models and mechanisms of the atmospheric processing of dust. The uptake of secondary acids was also dependent on the individual dust particle mineralogy; nitrate accumulated on calcium-rich dust while sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate-rich dust is a probable

  9. Experimental approaches and analytical technique for determining heavy metals in fallen dust at ferrosilicon production factory in Edfu, Aswan, Egypt

    PubMed Central

    Soltan, M.E.; Rageh, H.M.; Rageh, N.M.; Ahmed, M.E.

    2005-01-01

    In this study aimed to evaluate the pollution extent of metals and nonmetals inside and outside the ferrosilicon production factory in Edfu, Aswan, Egypt, raw materials (quartz, cokes, iron oxides), ferrosilicon alloy, silica fume, dust and suspended dust (at different sites) samples were collected from the factory, and fallen dust samples were collected from outside the factory, horizontally (at different sites and different distance and directions) and vertically (at different floors in the selected buildings). Gravimetric methods, X-ray fluorescence (XRF), flame photometer, wide range carbon determinator and atomic absorption spectroscopy tools were used for elements determination. The results indicating that the fallen dust and its element contents on southern factory walls being higher than those on eastern factory walls may be due to the nature of the dusts and effects of wind force and wind direction. Fallen dust levels in different regions outside the factory were found to be affected by the distance, direction and floors. The nature of dust samples was affected by gravity and the suspended dust in different factory units depended on the work capacity and method of handling materials by personnel in different production units. Silica fume was a complicated problem, had dangerous effect against the workers’ health, and was characterized by high concentrations of SiO2 (90.6%~93.6%) and heavy metals (Mn, 420.6×10−6~520.3×10−6; Fe, 2354×10−6~2685×10−6; Co, 80.7×10−6~101.6×10−6 and Ni, 5.3×10−6~6.05×10−6). The TSP (Total Suspended Particulate) levels in all factory units were higher than the recommended air quality value (70 μg/m3) under Egyptian law. The effect of ferrosilicon factory fallen dust on the surrounding regions decreased with increasing distance between the factory and these regions. The suspended dust samples in the factory units and their components greatly exceeded national and international standards, so health and

  10. Effects of dust additions on phytoplankton growth and DMS production in high CO2 northeast Pacific HNLC waters

    NASA Astrophysics Data System (ADS)

    Mélançon, J.; Levasseur, M.; Lizotte, M.; Scarratt, M.; Tremblay, J.-É.; Tortell, P.; Yang, G.-P.; Shi, G.-Y.; Gao, H.-W.; Semeniuk, D. M.; Robert, M.; Arychuk, M.; Johnson, K.; Sutherland, N.; Davelaar, M.; Nemcek, N.; Peña, A.; Richardson, W.

    2015-08-01

    Ocean acidification (OA) is likely to have an effect on the fertilizing potential of desert dust in high-nutrient, low-chlorophyll oceanic regions, either by modifying Fe speciation and bioavailability, or by altering phytoplankton Fe requirements and acquisition. To address this issue, short incubations (4 days) of northeast subarctic Pacific waters enriched with either FeSO4 or dust, and set at pH 8.0 (in situ) and 7.8 were conducted in August 2010. We assessed the impact of a decrease in pH on dissolved Fe concentration, phytoplankton biomass, taxonomy and productivity, and the production of dimethylsulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP). Chlorophyll a (chl a) remained unchanged in the controls and doubled in both the FeSO4-enriched and dust-enriched incubations, confirming the Fe-limited status of the plankton assemblage during the experiment. In the acidified treatments, a significant reduction (by 16-38 %) of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15 % reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. Lowering the pH affected mostly the haptophytes, but pelagophyte concentrations were also reduced in some acidified treatments. Acidification did not significantly alter DMSP and DMS concentrations. These results show that dust deposition events in a low-pH iron-limited Northeast subarctic Pacific are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean during the few days following fertilization and point to a low initial sensitivity of the DMSP and DMS dynamics to OA.

  11. Dust particle injector for hypervelocity accelerators provides high charge-to-mass ratio

    NASA Technical Reports Server (NTRS)

    Berg, O. E.

    1966-01-01

    Injector imparts a high charge-to-mass ratio to microparticles and injects them into an electrostatic accelerator so that the particles are accelerated to meteoric speeds. It employs relatively large masses in the anode and cathode structures with a relatively wide separation, thus permitting a large increase in the allowable injection voltages.

  12. How much dust does Enceladus eject?

    NASA Astrophysics Data System (ADS)

    Kempf, Sascha; Horanyi, Mihaly; Schmidt, Jürgen; Southworth, Ben

    2015-04-01

    There is an ongoing argument how much dust per second the ice volcanoes on Saturn's ice moon Enceladus eject. By adjusting their plume model to the dust flux measured by the Cassini dust detector during the close Enceladus flyby in 2005, as well as to the plume brightness in Cassini imaging, Schmidt et al. (2008) obtained a total dust production rate in the plumes of about 5 kg/s. On the other hand, Ingersoll and Ewald (2011) derived a dust production rate of 51 kg/s from photometry of very high phase-angle images of the plume, a method that is sensitive also to particles in the size range of microns and larger. Knowledge of the production rate is essential for estimating the dust to gas mass ratio, which in turn is an important constraint for finding the plume source mechanism. Here we report on numerical simulations of the Enceladus dust plume. We run a large number of dynamical simulations including gravity and Lorentz force to investigate the earliest phase of the ring particle life span. The magnetic field in the vicinity of Enceladus is based on the model by Simon et al. (2012). The evolution of the electrostatic charge carried by the initially uncharged grains is treated self-consistently. Our numerical simulations reproduce dust measurements by the Cassini Cosmic Dust Analyzer (CDA) during Cassini plume traversals as well as the snowfall pattern derived from ISS observations of the Enceladus surface (Schenk et al, 2011, EPSC abstract). Based on our simulation results we are able to draw conclusions about the dust production rate as well as wether the Enceladus dust plume constitutes a dusty plasma.

  13. Dust clouds around red giant stars - Evidence of sublimating comet disks?

    NASA Astrophysics Data System (ADS)

    Matese, J. J.; Whitmire, D. P.; Reynolds, R. T.

    1989-09-01

    The dust production by disk comets around intermediate mass stars evolving into red giants is studied, focusing on AGB supergiants. The model of Iben and Renzini (1983) is used to study the observed dust mass loss for AGB stars. An expression is obtained for the comet disk net dust production rate and values of the radius and black body temperature corresponding to peak sublimation are calculated for a range of stellar masses. Also, the fractional amount of dust released from a cometesimal disk during a classical nova outburst is estimated.

  14. Measurement of respirable superabsorbent polyacrylate (SAP) dust by ethanol derivatization using gas chromatography-mass spectrometry (GC-MS) detection.

    PubMed

    McCormack, Paul; Lemmo, John S; Macomber, Margaret; Holcomb, Mark L; Lieckfield, Robert

    2011-04-01

    Superabsorbent polyacrylate (SAP) is an important industrial chemical manufactured primarily as sodium polyacrylate but occasionally as potassium salt. It has many applications owing to its intrinsic physical property of very high water absorption, which can be more than 100 times it own weight. SAP is commonly used in disposable diapers and feminine hygiene products and is known by a number of synonyms-sodium polyacrylate, superabsorbent polyacrylate (SAP), polyacrylate absorbent (PA), and superabsorbent material (SAM). Germany and The Netherlands have adopted a nonbinding scientific guideline value 0.05 mg/m³ (8-hr time-weighted average, TWA) as the maximum allowable workplace concentration for the respirable dust of SAP (<10 μm particle diameter). Three industry associations representing Europe, the United States, and Asia have adopted the German scientific guideline value of 0.05 mg/m³ (8-hr TWA) as a voluntary guideline. A new test method based on alcohol derivatization of the acrylate was developed and validated for the analysis of respirable superabsorbent polyacrylate dust collected on filter cassettes in the workplace environment. This method is an alternative to the commonly used sodium-based method, which is limited owing to potential interference by other sources of sodium from the workplace and laboratory environments. The alcohol derivatization method effectively eliminates sodium interference from several classes of sodium compounds, as shown by their purposeful introduction at two and six times the equivalent amount of SAP present in reference samples. The accuracy of the method, as determined by comparison with sodium analysis of known reference samples, was greater than 80% over the study range of 5-50 μg of SAP dust. The lower reporting limit of the method is 3.0 μg of SAP per sample, which is equivalent to 3 (μg/m³) for an 8-hr sampling period at the recommended flow rate of 2.2 L/min. PMID:21416441

  15. EI MASS SPECTROMETRY OF BHT AND ITS ALTERATION PRODUCTS

    EPA Science Inventory

    The electron impact (El) mass spectra of 2,6-di-tert-butyl-4-methylphenol (BHT) and certain of its alteration products are described in detail. ccurate mass measurements confirm the element compositions of important fragment ions in the El spectra. Collisionally activated mass sp...

  16. Potential of mass algae production in Kuwait

    SciTech Connect

    Prokop, A.; Fekri, M.

    1984-11-01

    The rationale for efficient light absorption by algae at a production unit is given and design details of an intensive thin-layer technology outdoor (2.11m/sup 2/) unit are presented. Data on productivity under extreme conditions were collected. Maximum productivity data are close to those reported in the literature for similar geographic areas.

  17. Interstellar Dust Instrumentation

    NASA Astrophysics Data System (ADS)

    Sternovsky, Zoltan; Gruen, E.; Horanyi, M.; Drake, K.; Collette, A.; Kempf, S.; Srama, R.; Postberg, F.; Krueger, H.; Auer, S.

    2010-10-01

    Interstellar grains traversing the inner planetary system have been identified by the Ulysses dust detector. Space dust detectors on other missions confirmed this finding. Analysis of the Stardust collectors is under way to search for and analyze such exotic grains. Interstellar dust particles can be detected and analyzed in the near-Earth space environment. New instrumentation has been developed to determine the origin of dust particles and their elemental composition. A Dust Telescope is a combination of a Dust Trajectory Sensor (DTS, Rev. Sci. Instrum. 79, 084501, 2008) together with a high mass resolution mass analyzer for the chemical composition of dust particles in space. Dust particles' trajectories are determined by the measurement of induced electric signals when a charged grain flies through a position sensitive electrode system. A modern DTS can measure dust particles as small as 0.2 micron in radius and dust speeds up to 100 km/s. Large area chemical analyzers of 0.1 m2 sensitive area have been tested at a dust accelerator and it was demonstrated that they have sufficient mass resolution to resolve ions with atomic mass number up to >100 (Earth, Moon and Planets, DOI: 10.1007/s11038-005-9040-z, 2005; Rev. Sci. Instrum. 78, 014501, 2007). The advanced Dust Telescope is capable of identifying interstellar and interplanetary grains, and measuring their mass, velocity vector, charge, elemental and isotopic compositions. An Active Dust Collector combines a DTS with an aerogel or other dust collector materials, e.g. like the ones used on the Stardust mission. The combination of a DTS with a dust collector provides not only individual trajectories of the collected particles but also their impact time and position on the collector which proves essential in finding collected sub-micron sized grains on the collector.

  18. The impact of dust on sulfate aerosol, CN and CCN during an East Asian dust storm

    NASA Astrophysics Data System (ADS)

    Manktelow, P. T.; Carslaw, K. S.; Mann, G. W.; Spracklen, D. V.

    2010-01-01

    A global model of aerosol microphysics is used to simulate a large East Asian dust storm during the ACE-Asia experiment. We use the model together with size resolved measurements of aerosol number concentration and composition to examine how dust modified the production of sulfate aerosol and the particle size distribution in East Asian outflow. Simulated size distributions and mass concentrations of dust, sub- and super-micron sulfate agree well with observations from the C-130 aircraft. Modeled mass concentrations of fine sulfate (Dp<1.3 μm) decrease by ~10% due to uptake of sulfur species onto super-micron dust. We estimate that dust enhanced the mass concentration of coarse sulfate (Dp>1.0 μm) by more than an order of magnitude, but total sulfate concentrations increase by less than 2% because decreases in fine sulfate have a compensating effect. Our analysis shows that the sulfate associated with dust can be explained largely by the uptake of H2SO4 rather than reaction of SO2 on the dust surface, which we assume is suppressed once the particles are coated in sulfate. We suggest that many previous model investigations significantly overestimated SO2 oxidation on East Asian dust, possibly due to the neglect of surface saturation effects. We extend previous model experiments by examining how dust modified existing particle concentrations in Asian outflow. Total particle concentrations (condensation nuclei, CN) modeled in the dust-pollution plume are reduced by up to 20%, but we predict that dust led to less than 10% depletion in particles large enough to act as cloud condensation nuclei (CCN). Our analysis suggests that E. Asian dust storms have only a minor impact on sulfate particles present at climate-relevant sizes.

  19. The impact of dust on sulfate aerosol, CN and CCN during an East Asian dust storm

    NASA Astrophysics Data System (ADS)

    Manktelow, P. T.; Carslaw, K. S.; Mann, G. W.; Spracklen, D. V.

    2009-07-01

    A global model of aerosol microphysics is used to simulate a large East Asian dust storm during the ACE-Asia experiment. We use the model together with size resolved measurements of aerosol number concentration and composition to examine how dust modified the production of sulfate aerosol and the particle size distribution in East Asian outflow. Simulated size distributions and mass concentrations of dust, sub- and super-micron sulfate agree well with observations from the C-130 aircraft. Modelled mass concentrations of fine sulfate (Dp<1.3 μm) decrease by ~10% due to uptake of sulfur species onto super-micron dust. We estimate that dust enhanced the mass concentration of coarse sulfate (Dp<1.0 μm) by more than an order of magnitude, but total sulfate concentrations increase by less than 2% because decreases in fine sulfate have a compensating effect. Our analysis shows that the sulfate associated with dust can be explained largely by the uptake of H2SO4 rather than reaction of SO2 on the dust surface, which we assume is suppressed once the particles are coated in sulfate. We suggest that many previous model investigations significantly overestimated SO2 oxidation on East Asian dust, possibly due to the neglect of surface saturation effects. We extend previous model experiments by examining how dust modified existing particle concentrations in Asian outflow. Total particle concentrations modelled in the dust-pollution plume are reduced by up to 20%, but we predict that dust led to less than 10% depletion in particles large enough to act as cloud condensation nuclei. Our analysis suggests that E. Asian dust storms have only a minor impact on sulfate particles present at climate-relevant sizes.

  20. Mercury mass flow in iron and steel production process and its implications for mercury emission control.

    PubMed

    Wang, Fengyang; Wang, Shuxiao; Zhang, Lei; Yang, Hai; Gao, Wei; Wu, Qingru; Hao, Jiming

    2016-05-01

    The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%-49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%-36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039-0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%-73% of total mercury emissions to air. PMID:27155436

  1. Searching for Cool Dust in the Mid-to-Far Infrared: The Mass Loss Histories of the Hypergiants mu Cep, VY CMa, IRC +10420, and rho Cas

    NASA Astrophysics Data System (ADS)

    Humphreys, Roberta M.

    2016-01-01

    The most massive cool stars near the empircal upper limit of luminosity on the HR Diagram shed mass during brief, intense periods of enhanced mass loss. Their circumstellar environments show extensive and complex ejecta in scattered light at visual wavelengths. In the infrared, thermal emission from cooler dust in their ejecta can be used as a tracers of their mass loss histories. We combine high-resolution adaptive optics imaging from MMT/MIRAC (8 - 12 µm) with the new capabilities in far-infrared imaging of SOFIA/FORCAST and Herschel/PACS to probe further into the past for evidence of earlier mass loss for four famous objects: the red supergiants mu Cep and VY CMa and the yellow hypergiants IRC +10420 and rho Cas. We find evidence for a variable mass loss rate over several thousand years for mu Cep, while in contrast the lack of extended cold dust beyond VY CMa's visible ejecta indicates that its high mass loss episodes are recent. Despite its history of episodic mass loss, rho Cas has no resolved circumstellar ejecta. The new long wavelength photometry from FORCAST, however, confirms the presence of a slowly expanding dust shell from its 1946 event

  2. Determination of polybrominated diphenyl ethers in house dust using standard addition method and gas chromatography with electron capture and mass spectrometric detection.

    PubMed

    Król, Sylwia; Zabiegała, Bożena; Namieśnik, Jacek

    2012-08-01

    Monitoring of the environmental fate of polybrominated diphenyl ethers (PBDEs) involves determination of their concentration in air, airborne particles and settled dust. This requires the implementation of appropriate analytical tools like measuring instruments, reference materials and analytical procedures. In this study an analytical procedure was developed for determining PBDEs in samples with a complex matrix composition. The efficiencies of three different extraction techniques - Soxhlet extraction (SE), Accelerated Solvent Extraction (ASE) and Ultrasound Assisted Extraction (UAE) - were compared. The study investigated the possibility of using the standard addition method for estimating PBDEs levels. The GC-μECD system was successfully applied as an alternative to low resolution mass spectrometry (LRMS) for determining BDE-209 in dust samples. The developed analytical procedure was then used to analyze dust samples, collected from houses and computer suites in the Tri-city area (Gdansk, Gdynia and Sopot), in order to detect and quantify the presence of polybrominated diphenyl ethers (PBDEs) in the indoor environment. Concentrations of studied congeners (from triBDE to heptaBDE), obtained by chromatographic analysis of dust samples extracts, performed applying two measurement systems (GC-EIMS and GC-μECD) ranged between 331 and 3102 ng g(-1) for house dust and between dust. The highest concentrations were obtained for congeners with four, five and six bromine atoms (BDE-47, BDE-99, BDE-100 and BDE-153). Concentrations of BDE-209 ranged from 384 ng g(-1) (house dust) to 12,553 ng g(-1) (electronic dust). PMID:22749362

  3. Mass Loss from Hypergiant Stars: Searching for Cool Dust in the Near-to-Mid IR

    NASA Astrophysics Data System (ADS)

    Shenoy, Dinesh; Humphreys, Roberta M.; Jones, Terry Jay; Marengo, Massimo; Gehrz, Robert D.; Helton, L. Andrew

    2015-01-01

    The final fate of the most massive stars depends on their mass loss histories during their lifetimes. Hypergiant stars residing near the empircal upper limit of luminosity on the HR Diagram shed mass during brief, intense periods of enhanced mass loss, with amounts as high as 10-3 M⊙ in a single event. Their circumstellar environments show extensive and complex ejecta at visual wavelengths. To further probe their mass-loss histories for evidence of earlier mass loss we have extended the search of hypergiants' circumstellar enviroments into the mid-to-far infrared for four famous objects: the yellow hypergiants IRC +10420 and rho Cas and the red hypergiants VY CMa and mu Ceph. We present high-resolution adaptive optics imaging from LBT/LMIRCam (2 - 5 µm) and MMT/MIRAC (8 - 12 µm), combined with recently obtained far-IR imaging from 11 - 37 µm obtained with SOFIA/FORCAST (Cycle 2). We also discuss their long wavelength SEDs.

  4. Utilization of Electric Arc Furnace Dust as raw material for the production of ceramic and concrete building products.

    PubMed

    Sikalidis, Constantine; Mitrakas, Manassis

    2006-01-01

    The up to 20 wt% addition of the Electric Arc Furnace Dust (EAFD) hazardous waste on the properties of extruded clay-based ceramic building products fired at various temperatures (850 to 1050 degrees C), as well as of dolomite-concrete products was investigated. Chemical, mineralogical and particle size distribution analyses were performed in order to characterize the used EAFD. The results showed that the ceramic specimens prepared had water absorption, firing shrinkage, apparent density, mechanical strength, colour and leaching behaviour within accepted limits. Addition of 7.5 to 15 wt% EAFD presented improved properties, while 20 wt% seems to be the upper limit. Dolomite-concrete specimens were prepared by vibration and press-forming of mixtures containing cement, sand, dolomite, EAFD and water. Modulus of rupture values were significantly increased by the addition of EAFD. The leaching tests showed stabilization of all toxic metals within the sintered ceramic structure, while the leaching behaviour of lead in dolomite-concrete products needs further detailed study. PMID:16849138

  5. Inhaled house dust mite induces pulmonary T helper 2 cytokine production

    PubMed Central

    Gregory, L. G.; Causton, B.; Murdoch, J. R.; Mathie, S. A.; O’Donnell, V.; Thomas, C. P.; Priest, F. M.; Quint, D. J.; Lloyd, C. M.

    2012-01-01

    Background Inhaled house dust mite (HDM) results in T-helper (TH) 2 type pathology in unsensitized mice, in conjunction with airway hyperreactivity and airway remodelling. However, the pulmonary cytokine and chemokine profile has not been reported. Methods We have performed a time course analysis of the characteristic molecular mediators and cellular influx in the bronchoalveolar lavage (BAL) and lung in order to define the pulmonary inflammatory response to inhaled HDM extract. Mice were exposed five times a week to soluble HDM extract for 3 weeks. Lung function was measured in groups of mice at intervals following the final HDM challenge. Recruitment of inflammatory cells and inflammatory mediator production was then assessed in BAL and lungs of individual mice. Results We found that Th2 cytokines were significantly increased in BAL and lung after HDM challenge from as early as 2 h post-final challenge. The levels of cytokines and chemokines correlated with the influx of eosinophils and Th2 cells to the different compartments of the lung. However, the production of key cytokines such as IL-4, IL-5 and IL-13 preceded the increase in airways resistance. Conclusion Inhaled HDM challenge induces a classical Th2 inflammatory mediator profile in the BAL and lung. These data are important for studies determining the efficacy of novel treatment strategies for allergic airways disease. PMID:19545261

  6. The transition from carbon dust to silicate production in low-metallicity asymptotic giant branch and super-asymptotic giant branch stars

    NASA Astrophysics Data System (ADS)

    Ventura, P.; di Criscienzo, M.; Schneider, R.; Carini, R.; Valiante, R.; D'Antona, F.; Gallerani, S.; Maiolino, R.; Tornambé, A.

    2012-02-01

    We compute the mass and composition of dust produced by stars with masses in the range ? and with a metallicity of Z= 0.001 during their asymptotic giant branch (AGB) and super-AGB phases. Stellar evolution is followed from the pre-main-sequence phase using the code ATON which provides, at each time-step, the thermodynamics and the chemical structure of the wind. We use a simple model to describe the growth of the dust grains under the hypothesis of a time-independent, spherically symmetric stellar wind. Although part of the modelling which describes the stellar outflow is not completely realistic, this approach allows a straight comparison with results based on similar assumptions present in the literature, and thus can be used as an indication of the uncertainties affecting the theoretical investigations focused on the dust formation process in the surroundings of AGB stars. We find that the total mass of dust injected by AGB stars in the interstellar medium does not increase monotonically with stellar mass and ranges between a minimum of ? for the 1.5-? stellar model up to ?, for the 6-? case. Dust composition depends on the stellar mass: low-mass stars (?) produce carbon-rich dust, whereas more massive stars, experiencing Hot Bottom Burning, never reach the C-star stage, and produce silicates and iron. This is in partial disagreement with previous investigations in the literature, which are based on synthetic AGB models and predict that, when the initial metallicity is Z= 0.001, carbon-rich dust is formed at all stellar masses. The differences are due to the different modelling of turbulent convection in the super-adiabaticity regime. Also in this case, like for other physical features of the AGB, the treatment of super-adiabatic convection shows up as the most relevant issue affecting the dust formation process. We also investigate super-AGB stars with masses in the range ? that evolve over an ONe core. Due to a favourable combination of mass-loss and Hot

  7. Niamey Dust Observations

    DOE Data Explorer

    Flynn, Connor

    2008-10-01

    Niamey aerosol are composed of two main components: dust due to the proximity of the Sahara Desert, and soot from local and regional biomass burning. The purpose of this data product is to identify when the local conditions are dominated by the dust component so that the properties of the dust events can be further studied.

  8. Evolution of interstellar dust and stardust in the solar neighbourhood

    NASA Astrophysics Data System (ADS)

    Zhukovska, S.; Gail, H.-P.; Trieloff, M.

    2008-02-01

    Aims:We studied the evolution of the abundance in interstellar dust species that originate in stellar sources and from condensation in molecular clouds in the local interstellar medium of the Milky Way. We determined from this the input of dust material to the Solar System. Methods: A one-zone chemical evolution model of the Milky Way for the elemental composition of the disk combined with an evolution model for its interstellar dust component similar to that of Dwek (1998) is developed. The dust model considers dust-mass return from AGB stars as calculated from synthetic AGB models combined with models for dust condensation in stellar outflows. Supernova dust formation is included in a simple parametrised form that is gauged by observed abundances of presolar dust grains with a supernova origin. For dust growth in the ISM, a simple method is developed for coupling this with disk and dust evolution models. Results: A chemical evolution model of the solar neighbourhood in the Milky Way is calculated, which forms the basis for calculating a model of the evolution of the interstellar dust population at the galactocentric radius of the Milky Way. The model successfully passes all standard tests for the reliability of such models. In particular the abundance evolution of the important dust-forming elements is compared with observational results for the metallicity-dependent evolution of the abundances for G-type stars from the solar neighbourhood. It is found that the new tables of Nomoto et al. (2006) for the heavy element production give much better results for the abundance evolution of these important elements than the widely used tables of Woosley & Weaver (1995). The time evolution for the abundance of the following dust species is followed in the model: silicate, carbon, silicon carbide, and iron dust from AGB stars and from supernovae, as well as silicate, carbon, and iron dust grown in molecular clouds. It is shown that the interstellar dust population is

  9. Direct observations of the atmospheric processing of Asian mineral dust

    NASA Astrophysics Data System (ADS)

    Sullivan, R. C.; Guazzotti, S. A.; Sodeman, D. A.; Prather, K. A.

    2007-02-01

    The accumulation of secondary acids and ammonium on individual mineral dust particles during ACE-Asia has been measured with an online single-particle mass spectrometer, the ATOFMS. Changes in the amounts of sulphate, nitrate, and chloride mixed with dust particles correlate with air masses from different source regions. The uptake of secondary acids depended on the individual dust particle mineralogy; high amounts of nitrate accumulated on calcium-rich dust while high amounts of sulphate accumulated on aluminosilicate-rich dust. Oxidation of S(IV) to S(VI) by iron in the aluminosilicate dust is a possible explanation for this enrichment of sulphate, which has important consequences for the fertilization of remote oceans by soluble iron. This study shows the segregation of sulphate from nitrate and chloride in individual aged dust particles for the first time. A transport and aging timeline provides an explanation for the observed segregation. Our data suggests that sulphate became mixed with the dust first. This implies that the transport pathway is more important than the reaction kinetics in determining which species accumulate on mineral dust. Early in the study, dust particles in volcanically influenced air masses were mixed predominately with sulphate. Dust mixed with chloride then dominated over sulphate and nitrate when a major dust front reached the R. V. Ronald Brown. We hypothesize that the rapid increase in chloride on dust was due to mixing with HCl(g) released from acidified sea salt particles induced by heterogeneous reaction with volcanic SO2(g), prior to the arrival of the dust front. The amount of ammonium mixed with dust correlated strongly with the total amount of secondary acid reaction products in the dust. Submicron dust and ammonium sulphate were internally mixed, contrary to frequent reports that they exist as external mixtures. The size distribution of the mixing state of dust with these secondary species validates previous mechanisms of

  10. Pulmonary function in relation to total dust exposure at a bauxite refinery and alumina-based chemical products plant

    SciTech Connect

    Townsend, M.C.; Enterline, P.E.; Sussman, N.B.; Bonney, T.B.; Rippey, L.L.

    1985-12-01

    A cross-sectional study of 1,142 male employees at the Arkansas Operations of a large aluminum production company examined the effect on pulmonary function of chronic exposure to total dust produced in the mining and refining of bauxite and the production of alumina chemicals. Never smokers, ex-smokers, and current smokers were analyzed separately. Among never smokers, a pattern of decreasing FEV1 was observed in relation to increasing duration and cumulative total dust exposure. Among never smokers with cumulative total dust exposures of greater than or equal to 100 mg/m3 yr and greater than or equal to 20 yr of exposure, there was a mean reduction from the predicted FEV1 of 0.29 to 0.39 L, in addition to a 3- to 4-fold excess of observed/expected numbers of subjects with FEV1 less than 80% of predicted. These results were observed relative to an external and an internal comparison group. Among current smokers, the deviations from predicted and the excess numbers of subjects with FEV1 less than 80% of predicted were larger in all exposure groups than for the never smokers. However, the quality of the smoking data was inadequate to allow separation of the effects of smoking and dust exposure.