photoelectric absorption model such as phabs. The extinction curve contains no spectral features and is characterized by a powerlaw slope over spectral ...

Optical absorption spectra of interplanetary dust particles 2-30 microns in size collected in the atmosphere at an altitude of 20 km by inertial impactors mounted on NASA U-2 aircraft are reported. Fourier transform absorption spectroscopy of crushed samples of the particles reveals a broad feature in the region ...

The features of absorption and emission spectra of interplanetary dust are analyzed. The absence of overlap between these two spectra is discussed. The comparison between the 3.4 microns band attributed to aliphatic C-H bonds seen in absorption and the 3....

It is shown that the study of the interstellar extinction and spectral features (absorption/emission) in the infrared, observed in astronomical spectra, provides indications about likely material candidates for cosmic dust. Carbonaceous materials as silic...

The possibilities that unidentified interstellar dust particles contain organic matter and even microbes and viruses are explored, along with the methods for the identification. The interstellar extinction curve allows determination of the dimming effect on starlight by interposed dust clouds, and is used to identify the grains by measurement of the IR and ...

o Dust: prominent iron features (Fe L and K-edge), absent in IR band ... XANES ( Xray Absorption Near Edge Structure). + EXAFS (Extended X-ray absorption ...

We investigate the effects of dust extinction on integrated absorption-line indices that are widely used to derive constraints on the ages and metallicities of composite stellar systems. Typically, absorption-line studies have been performed on globular clusters or elliptical galaxies, which are mostly dust-free ...

Springtime desert dust storms regularly deposit radiatively absorbing dust upon the San Juan Mountains of southwestern Colorado. The dust deposits reduce the albedo of snow in visible wavelengths, accelerate grain metamorphism, and increase grain size. Because the dust increases net visible ...

The first detection of the silicate absorption feature in Active Galactic Nuclei (AGNs) was made at 9.7?m for the prototypical Seyfert 2 galaxy NGC1068 35 yr ago, indicating the presence of a large column of silicate dust in the line of sight to the nucleus. It is now well recognized that type 2 AGNs exhibit prominent silicate ...

It is argued that irradiated tetrahedron silicates in the interstellar dust are one of the main contributors responsible for many of the diffuse absorption features of interstellar bands in the visible region. Attention is given to the stable absorption bands of irradiated tetrahedron silicates with particular ...

Dust and mid-IR properties of Interacting Galaxies Vassilis Charmandaris IRS Science Center photon in 10 penetrates � Continuum bump at ~100�m � Presence of ice absorption features (3.1 �m ) � IRJ, 2001) Really hot dust (~200-1500K) in a equilibrium is observed via a near/mid-IR "bump" close to tori

Stars on the asymptotic giant branch (AGB) produce dust in their circumstellar shells. The nature of the dust-forming environment is influenced by the evolution of the stars, in terms of both chemistry and density, leading to an evolution in the nature of the dust that is produced. Carbon-rich AGB stars are known to produce silicon ...

Because interstellar dust is closely related to the evolution of matter in the galactic environment and many other astrophysical phenomena, the laboratory synthesis of interstellar dust analogs has received significant attention over the past decade. To simulate the ultraviolet (UV) interstellar extinction feature at 217.5 nm ...

The interstellar medium (ISM) has a multiphase structure characterized by gas, dust and molecules. It is possible to probe the ISM through observation of its absorption lines and edges in X-ray spectra of background sources. We present a high quality RGS spectrum of the low-mass X-ray binary (LMXB) GS 1826-238 with a detailed treatment of the ...

We present 7-14 ?m Infrared Space Observatory (ISO) spectroscopy of 12 M-type evolved stars in the Large Magellanic Cloud (LMC), in order to study the dust mineralogy and condensation process around these stars. The sample stars show a broad dust feature in the 7-14 ?m region, which is seen in either emission or (self-) ...

The possibility is considered that a broad absorption feature centered on a wavelength close to 2200 A, derived from scattering studies of dust clouds observed during the storm at the Martian surface in 1971, may be a signature of highly complex organic or prebiotic molecules. Attention is given to considerations reported by Hoyle and ...

We introduce a model of radiative transfer in circumstellar dust shells. By assuming that the shell is both isothermal and its thickness is small compared to its radius, the model is simple enough for students to grasp and yet still provides a quantitative description of the relevant physical features. The isothermal model can be used in a classroom ...

... Accession Number : AD0836883. Title : INFRARED ABSORPTION SPECTRA OF ATMOSPHERIC DUST,. Corporate Author ...

Numerical radiative-transfer models are used to discuss the properties of circumstellar dust grains around the premain-sequence star AB Aur (HD 31293). It is assumed that the dust consists of a silicate-graphite mixture with Draine and Lee (1984) optical properties. The modeling technique is to match the observed FUV through FIR energy distribution with ...

Transmission electron microscopy of a hydrated interplanetary dust particle (IDP) indicates that it contains abundant magnesium-iron carbonates, primarily breunnerite and magnesian siderite. This IDP displays a strong absorption band at 6.8 micrometers in its infrared spectrum, similar to that in certain protostellar spectra. The carbonates probably ...

An electrical connector was developed that is tolerant of the presence of lunar dust. Novel features

In spite of some similarities with the infrared features observed in the interstellar medium, the 3 micron signature observed in comet Halley's spectrum shows two distinct differences: (1) the 3.28 micron and 3.37 micron cometary features are both in emission, while the 3.37 micron interstellar feature is most often observed in ...

Beta Pictoris is the best studied Vega-type star with the optically resolved circumstellar dust disk. However, the typical size of dust particles in the disk is still an open question. Several optical observations have indicated that the color of the disk is same as the beta Pic itself within the observational uncertainties. This result has been ...

The remote sensing data sets that typically are used to assess dust cover on Mars are thermal inertia and albedo measurements. Thermal inertia measurements are well suited to identifying surfaces that are dust covered but are ineffective for dust layers less than a few centimeters thick. Albedo measurements can be used to infer the ...

We investigate the mid-IR (5-38 um) properties of Seyfert nuclei using archival Spitzer/IRS spectra. Seyfert mid-IR spectra show a large range in continuum shapes and the contributions from the polycyclic aromatic hydrocarbon (PAH) bands. The spectra also show a number of low- and high-ionization forbidden emission lines. While the PAH contribution is expected to come from the star-forming regions ...

We present Spitzer InfraRed Spectrograph (IRS) mid-infrared (5-35 ?m) spectra of a complete flux-limited sample (>=3 mJy at 8 ?m) of young stellar object (YSO) candidates selected on the basis of their infrared colors in the Serpens Molecular Cloud. Spectra of 147 sources are presented and classified. Background stars (with slope consistent with a reddened stellar spectrum and silicate ...

Aims: In this paper we study the effects of inclusions and porosities on the emission properties of silicate grains and compare the model curves with the observed infrared emission from circumstellar dust. Methods: We calculated the absorption efficiency of the composite grain, made up of a host silicate oblate spheroid and inclusions of ice/graphite/or ...

May 24, 2001 ... The feature is a dust devil. Dust devils are spinning, columnar vortices of wind that move across the landscape, pick up dust, ...

The Interstellar Medium Absorption Gradient Experiment Rocket (IMAGER) will probe the correlation between ultraviolet dust extinction, and the metallicity and radiation environment in M101. With four 400�-wide bandpasses, IMAGER targets UV extinction features and will utilize M101 as a laboratory for studying ...

Prior to mineral dust deposition affecting albedo, aerosols can have direct and indirect effects on local to regional scale climate by changing both the shortwave and longwave radiative forcing. In addition, mineral dust causes health hazards, such as respiratory-related illnesses and deaths, loss of agricultural soil, and safety hazards to aviation and ...

... Title : WEATHER MODIFICATION BY CARBON DUST ABSORPTION OF SOLAR ENERGY, IN: JOURNAL OF APPLIED METEOROLOGY, VOL15 ...

The Dust in the Interstellar Medium model solves for the absorption and scattering of light from spherical particles assuming a Mie solution.

Interstellar dust is characterized by strong absorption in the ultraviolet and the mid-IR. Current models of interstellar dust are based on three chemically distinct components: a form of carbon (usually graphite), a silicate, and a blend of polycyclic aromatic hydrocarbons or other carbonaceous material. Previous work using effective ...

A gamma ray burst with strong optical-UV emission occuring in a molecular cloud will photodissociate H2, photoionize H2, H, and He, and destroy dust grains. We model these processes, including time-dependent radiative transfer in both continuum radiation and the resonance lines of H2. The UV will pump H2 into vibrationally-excited levels. We calculate the ...

We present observations of a local dust storm performed by the OMEGA and PFS instruments aboard Mars Express. OMEGA observations are used to retrieve the dust single-scattering albedo in the spectral range 0.4-4.0 ?m. The single-scattering albedo shows fairly constant values between 0.6 and 2.6 ?m, and a sharp decrease at wavelengths shorter than 0.6 ?m, ...

demonstrate that Saharan dust absorption of solar radiation is several times smaller than ..... compare the two methods, linear fits (color lines) were performed ...

One of the key questions of infrared astronomy is how the characteristics of dust depend on the physical properties of the surrounding medium. To address this question, we present results from the Spitzer Space Telescope on two projects designed to study the dust properties of a sample of 25 Planetary Nebulae (PNe) in the Magellanic Clouds, and three ...

Variable absorption features were observed in the visible and ultraviolet spectrum of beta-Pictoris soon after this star gained attention in the early 1980s due to its large IRAS infrared excess and the discovery, from optical imaging, of an edge-on dust disk. The absorption has been attributed to the evaporation ...

The authors have obtained spectra of the thermal emission from Mars in the 5.4-10.5 {mu}m wavelength domain at a resolving power of about 60 from the Kuiper Airborne Observatory. These data, as well as spectral fluxes of single spots based using the star {alpha} Tau as a calibration standard, show a number of emission and absorption features. They are ...

We present the column densities of heavy elements and dust depletion studies in two strong Mg II absorption systems at z ~ 1.4 displaying the 2175 � dust extinction feature. Column densities are measured from low-ionization absorption lines using an Apparent Optical Depth Method on the ...

A model for intergalactic dust composed of graphite grains is presented. The model is examined in the context of the Rayleigh approximation for results due to long-wavelength scattering and absorption by the grains. The temperature of the scattering grains as a function of redshift is found, based on reasonable assumptions of the density of optical ...

Observationally, both the 3.4 ?m aliphatic hydrocarbon C-H stretching absorption feature and the 9.7 ?m amorphous silicate Si-O stretching absorption feature show considerable variations from the local diffuse interstellar medium (ISM) to Galactic center (GC): both the ratio of the visual extinction (AV) to the 9.7 ...

The authors present new HST STIS NUV-MAMA and STIS CCD observations of the BL Lac object AO 0235+164 and the intervening damped Ly {alpha} (DLA) line at z{sub {alpha}} = 0.524. The line profile gives N(HI) = 5 {+-} 1 x 10{sup 21} cm{sup -2} and, combined with the H I 21 cm absorption data leads to a spin temperature of Ts = 220 K {+-} 60 K. Those spectra also show a strong, ...

ABSTRACT Total dust samples produced by machining three commercial asbestos-cement products (autoclaved sheet, non-autoclaved sheet, pipe) were examined for their dimensional, surface, and physicochemical characteristics. Microscopic inspection of dust fractions with different settling characteristics in air allowed determination of the simple dimensional ...

We present intermediate-resolution ( lambda / Delta lambda ~ 60) spectra of 21 ultracompact H II regions in the spectral range from 3 to 13 mu m. The 9.7 mu m silicate feature is seen in absorption, and the 12.8 mu m [Ne II] fine structure line is seen in emission toward most of the observed nebulae. The strengths of both features vary ...

to the higher signal that #12;� 6 � was originally there. 3.4. Zodiacal Light As somewhat of a surprise to us of the night show evidence for a zodiacal absorption feature near H. Although observations were only taken of the observation (due to solar system rotation of the zodiacal dust along the line of sight). Work by G. Madsen

New measurements of the reduction of the V-band surface brightness across the prominent dust feature in the galaxy NGC 4826 are compared with corresponding increases in the V-K' color within the context of radiative transfer models invoking both absorption and scattering. The K'-band surface brightness is found to be higher than ...

We have observed a sample of 35 long-period variables (LPVs) and four Cepheid variables in the vicinity of 23 Galactic globular clusters using the Infrared Spectrograph on the Spitzer Space Telescope. The LPVs in the sample cover a range of metallicities from near solar to about 1/40th solar. The dust mass-loss rate (MLR) from the stars increases with pulsation period and ...

The strength of the 9.7 microns absorption band in the radiation from the galactic center is used to

... (Author). Descriptors : (*STRATOSPHERE), TEMPERATURE, DIURNAL VARIATIONS, OZONE, WATER VAPOR, DUST, ABSORPTION. ...

Infrared absorption and emission features observed spectroscopically in our Galaxy allow to probe the composition of solid dust grains, their evolution and thus follow the cycling of matter in the Galaxy. Many observables do reveal the presence of large amounts of carbonaceous particles in space, other than the PAH-like emission lines. ...

(2000) (see Section 2), the retrieval uncertainty of aerosol absorption ... 2001 ), desert dust absorption of solar radiation is very weak for wavelengths ...

The goal of the present paper is to investigate the circumstellar material around the brightest dust-enshrouded sources in the central stellar cluster of the Milky Way. Observations have been carried out at the European Southern Observatory's Very Large Telescope (VLT) on Paranal, Chile. We have used the long wavelength (LWS3) low resolution (LR) spectroscopic mode of the ...

We use high spatial resolution IR data to investigate the origin of the silicate emission in a Seyfert 2 AGN and to probe the chemistry of the torus in NGC~1068. In NGC~2110, the closest known type 2 AGN with silicate emission features, mid-IR imaging and spectroscopy enable us to set tight constraints on the location of the emitting material (within 32 pc of the nucleus). ...

This paper studies the effects of the presence of dust particles with variable charge, in fully ionized, homogeneous, magnetized plasma of electrons and ions, with the electrons and ions described by bi-Maxwellian distributions in the equilibrium. The dispersion relation and the absorption rate are obtained for low frequency waves, with frequencies much ...

The speciation of Fe and Mn in road dust particles, collected on the walls and floor of the ventilation shaft of Traforo del San Bernardo highway tunnel, was studied by means of XAS spectroscopy. Absorption spectra were recorded on BM8 at the ESRF (Grenoble, France) at the Fe and Mn K-edges. Several reference compounds were measured along with the samples, ...

This MOC wide-angle view shows a large, regional dust storm in Noachis Terra on November 26, 1997. The dust storm is the large, cloudy feature in the lower ...

The feature is a dust devil. Dust devils are spinning, columnar vortices of ... Dust devils are a common occurrence in dry and desert landscapes on Earth as ...

... of this systematic investigation is to gain further understanding of the details of various absorption features in the vicinity of the K absorption edge of ...

The interstellar medium (ISM) has a multiphase structure characterized by gas, dust and molecules. The interstellar gas consists of different charge states: neutral, weakly-ionized and highly-ionized. Dust is mainly found in carbonaceous and silicates compounds, and molecules like CO and CH are also common. Through the study of the X-ray ...

We observed a sample of evolved stars in the Large and Small Magellanic Clouds (LMC and SMC) with the Infrared Spectrograph on the Spitzer Space Telescope. Comparing samples from the SMC, LMC, and the Galaxy reveals that the dust-production rate depends on metallicity for oxygen-rich stars, but carbon stars with similar pulsation properties produce similar quantities of ...

The absorption, scattering, and re-emission of light by dust grains in space affects the interpretation of stellar formation processes, galactic star formation rates, intrinsic spectral energy distributions of stars along given sightlines, and observed spectral signatures of a variety of astronomical object classes. Quantifying optical properties of ...

BC absorption of solar radiation is estimated to be 0.5 W/m2, a ... and dust transported from the Sahara [Gobbi et al., 2000]. Dust preferential absorption ...

This thesis deals with some aspects of circumstellar dust shells. This dust shell, emitting infrared radiation, is described by way of its absorptive and emissive properties as well as by the transfer of radiation through the dust shell itself. Model calc...

We present Spitzer IRS data on 19 asymptotic giant branch (AGB) stars in the Large Magellanic Cloud, complementing existing published data sets of carbon stars in both Magellanic Clouds and the Milky Way, to investigate the effects of metallicity on dust and molecular spectral features arising from the circumstellar envelope. We find that the C2H 2 P- and ...

High signal-to-noise ratio spectra are presented of the 10-?m silicate absorption feature in lines of sight towards Elias 16 and 18 in the Taurus dark cloud, and towards the heavily reddened supergiant Cyg OB2 no. 12. The observations are fitted with laboratory and astronomical spectra to produce intrinsic absorption profiles. These ...

Observations of the 1(01) --> 0(00) rotational transitions of A and E state acetaldehyde are reported. The transitions were detected, for the first time in interstellar space, in the cold dust clouds TMC-1 and L134N, and in Sgr B2. This is also the first time acetaldehyde has been found in a dust cloud and is the most complex oxygen-bearing molecule ...

Observations of the 1/sub o1/..-->..0/sub 00/ rotational transitions of A and E state acetaldehyde are reported. The transitions were detected, for the first time in interstellar space, in the cold dust clouds TMC-1 and L134N, and in Sgr B2. This is also the first time acetaldehyde has been found in a dust cloud and is the most complex oxygen-bearing ...

Gases in the Martian atmosphere, including CO{sub 2}, H{sub 2}O, CO, and O{sub 3}, combine to produce some absorption at most infrared wavelengths. Line-by-line and quasi-random models are used to derive synthetic spectra of dust-free Martian atmospheres. These spectra show where gases absorb most strongly and provide a baseline for comparison with the ...

This study investigates the influence of dust-radiation effects on the modification of the Saharan air layer (SAL) and environmental shear. A tracer model based on the Weather Research and Forecast model was developed to examine the influence using a dust outbreak event. Two numerical experiments were conducted with (ON) and without (OFF) the ...

We have searched for the 9.7 micrometer silicate feature in four quasar absorption systems at absorption redshifts 0.4 < z < 1.3, using data from the Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. These systems were chosen because of hints of their dusty nature from optical/UV spectra of the quasars. Three of ...

We present findings for DG Tau B and VV CrA, two of the objects observed in our Spitzer Infrared Spectrograph (IRS) project to search for molecular absorption in edge-on disks, along with near-IR spectroscopy of the CO fundamental transitions and mid-IR imaging. While the only gas absorption seen in the Spitzer IRS spectrum toward DG Tau B is CO2, we use ...

ISO spectroscopy has revealed that the spectra of ULIRGs are not simply an ultra-luminous blend of AGN and starburst spectra. Instead, the 5-15 micron spectra show clear signs of ice and silicate absorption features, which distort their mid-infrared spectra. Especially puzzling are the 'modified' PAH emission features seen in the ...

The composition and history of dust in the diffuse ISM was studied using 3600-2700/cm absorption spectra of objects which have widely varying amounts of visual extinctions along different lines of sight. The 3300/cm and 2950/cm features are attributed to O-H and C-H stretching vibrations, respectively. The O-H ...

... Title : TECHNOLOGICAL FEATURES OF THE OPTICAL ABSORPTION METHOD OF LEAK TESTING OF VESSEL STRUCTURES. ...

The interstellar absorption band centred on 2175 � that is conventionally attributed to monodisperse graphite spheres of radii 0.02 ?m is more plausibly explained as arising from biologically derived aromatic molecules. On the basis of panspermia models, interstellar dust includes a substantial fraction of biomaterial in various stages of degradation. We ...

We have observed a sample of 36 objects in the Small Magellanic Cloud (SMC) with the Infrared Spectrometer on the Spitzer Space Telescope. Nineteen of these sources are carbon stars. An examination of the near- and mid-infrared photometry shows that the carbon-rich and oxygen-rich dust sources follow two easily separated sequences. A comparison of the spectra of the 19 carbon ...

We have searched for interstellar or circumstellar absorption lines in the center of Ca II K towards bright A-type stars that are mostly within 80 pc of the Sun. Narrow absorption features are found in about 30 % of the 28 normal main-sequence A stars and 18 metal-deficient lambda Bootis stars studied. We have determined surface ...

We present the results of Spitzer Infrared Spectrograph low-resolution infrared 5-35 ?m spectroscopy of nearby ultraluminous infrared galaxies (ULIRGs) at z<0.15. We focus on the search for the signatures of buried active galactic nuclei (AGNs) in the complete sample of ULIRGs classified optically as non-Seyferts (LINERs or H II regions). In addition to polycyclic aromatic hydrocarbon (PAH) ...

Mass-extinction coefficients of soil-derived atmospheric dust often are determined largely by the absorption (rather than scattering) by individual particles, especially at longer infrared wavelengths. Under many conditions, reasonable estimates of mass-extinction coefficients of dusts can be made from absorption ...

We present the results of near-infrared (NIR) multi-epoch observations of the optical transient in the nearby galaxy NGC 300 (NGC 300-OT) at 398 and 582 days after the discovery with the Infrared Camera (IRC) on board AKARI. NIR spectra (2-5 ?m) of NGC 300-OT were obtained for the first time. They show no prominent emission nor absorption features, but are ...

We present the results of near-infrared (NIR) multi-epoch observations of the optical transient in the nearby galaxy NGC 300 (NGC 300-OT) at 398 and 582 days after the discovery with the Infrared Camera (IRC) on board AKARI. NIR spectra (2-5 {mu}m) of NGC 300-OT were obtained for the first time. They show no prominent emission nor absorption features, but ...

... hard-crust palliatives, a higher concentration led to better dust abatement and thus ... slow absorption rate of these products, leading to excess ...

During the Apollo program the effects of lunar dust on thermal control surfaces was found to be more

... and submillimeter waves propagating through these dust clouds can suffer various degrading effects including absorption, scattering, decorrelation ...

Spectra of objects which lie along several lines of sight through the diffuse interstellar medium (DISM) reveal an absorption feature near 3.4 micrometers, which has been attributed to saturated aliphatic hydrocarbons on interstellar grains. The similarity of the absorption bands near 3.4 micrometers (2950 cm-1) along different lines ...

Random covalent network (RCN) theory is applied to describe the infrared spectroscopic properties of carbonaceous solids with compositions containing a mixture of aromatic, aliphatic, and diamond-like hydrocarbons. Application of this technique to carbonaceous dust is equivalent to the synthesis of solids whose structure and bonding satisfy stoichiometry while minimizing ...

We present AKARI/IRC observations of a sample of six extremely red IRAS sources, of which three are variable OH/IR stars and the rest are early post-AGB stars. The OH/IR stars show a red continuum with the expected strong 10 ?m silicate absorption feature, while the post-AGB stars show an even redder continuum accompanied with a comparably weak silicate ...

The reaction of atomic hydrogen with few-layer buckminsterfullerene films deposited on silicon in ultrahigh vacuum produces fullerane mixtures, which are studied in situ by high resolution electron energy loss spectroscopy. The vibrational and electronic excitation spectra are measured and discussed. Their main features are compared to observational data, including the ...

Cycling of matter between the ISM and stars drives the evolution of a galaxy's visible matter and its emission characteristics. To understand this recycling, the SAGE legacy project has surveyed the Large Magellanic Cloud with IRAC and MIPS to study the physical processes of the ISM, the formation of new stars and the injection of mass by evolved stars and their relationships on the galaxy-wide ...

We present preliminary Spitzer IRS and MIPS data of young dust-reddened quasars. These quasars were selected using the FIRST-2MASS survey and have large optical reddenings (E(B-V) 1.0). Hubble ACS images of these objects revealed them to be young quasars in which the host galaxies show clear signs of merger. The red quasars are most likely an evolutionary step in the ...

Interplanetary dust (IPD) scatters solar radiation which results in the zodiacal light that dominates the celestial diffuse brightness at optical and near-infrared wavelengths. Both asteroid collisions and cometary ejections produce the IPD, but the relative contribution from these two sources is still unknown. The low resolution spectrometer (LRS) onboard the Cosmic Infrared ...

Interplanetary dust (IPD) scatters solar radiation which results in the zodiacal light that dominates the celestial diffuse brightness at optical and near-infrared wavelengths. Both asteroid collisions and cometary ejections produce the IPD, but the relative contribution from these two sources is still unknown. The Low Resolution Spectrometer (LRS) onboard the Cosmic Infrared ...

Interplanetary dust (IPD) scatters solar radiation which results in the zodiacal light that dominates the celestial diffuse brightness at optical and near-infrared wavelengths. Both asteroid collisions and cometary ejections produce the IPD, but the relative contribution from these two sources is still unknown. The low resolution spectrometer (LRS) onboard the Cosmic Infrared ...

We present observations of solid-state absorption features due to water ice, CO ice, and silicate dust in the spectrum of the bright infrared source (IRS 1) associated with the Herbig-Haro nebula HH 100 in the R Coronae Australis dark cloud. These absorptions are shown to arise predominantly in the molecular cloud ...

Measurements on spectral dependence of aerosol light absorption and BC mass concentrations were made at various locations between Ahmedabad (23.03�N, 72.50�E) and Hyderabad (17.47�N, 78.45�E) during February 2004. Average concentration of BC was close to 2 ?g/m3 which is about 2 to 5% of the total aerosol mass loading measured at the surface. ...

A linear relationship between concentration of sulfur dioxide (SO2) and optical parameter (OP) is established using the Beer-Lambert law. The SO2 measuring system is set up to measure the concentration of sulfur dioxide in the wavelength range 275-315 nm. Experimental results indicate that the detection limit of the sulfur dioxide measuring system is below 0.2 ppm per meter of path length, and the ...

The X-ray absorption model can be computed for various metallicities by sim- ple scaling of the Solar abundances by a constant factor. ...

gaseous absorption (ozone, water vapor, oxygen). Rayleigh scattering by air molecules. Mie scattering and absorption by aerosols (haze, dust, pollution) ...

... ABSORPTION SPECTRA OF ATMOSPHERIC DUST OVER AN INTERIOR DESERT-PURE AND APPLIED GEOPHYSICS, V74, NO3, P151-164. ...

... Title : Contributions of Particle Absorption to Mass Extinction Coefficients (0. 55-14Micrometer) of Soil-Derived Atmospheric Dusts. ...

We present spectropolarimetry of the solid CO feature at 4.67 ?m along the line of sight to Elias 16, a field star background to the Taurus dark cloud. A clear increase in polarization is observed across the feature with the peak of polarization shifted in wavelength relative to the peak of absorption. This shows that ...

A recently detected absorption feature at 3.53 microns in the spectrum of W33A has been assigned to methanol (CH3OH). Its optical depth implies that methanol is the second most abundant molecule (7 percent relative to H2O) in the grain mantles in the line of sight toward W33A observed to date. Laboratory experiments have shown that the implied abundance is ...

As it is well known established that significant ecosystems effects can be produced by pollutants generated many hundreds of kilometres away. Desert is natural laboratories containing valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Dust is a key species of many biogeochemical. One important effect of the ...

A coherent picture of the dust composition and its physical characteristics in the various phases of the interstellar medium was the central theme. Topics addressed included: dust in diffuse interstellar medium; overidentified infrared emission features; dust in dense clouds; dust in galaxies; ...

Dust particles collected in the stratosphere that have chondritic elemental abundances provide a new form of extraterrestrial matter for laboratory study. Spectral transmission measurements from 2.5 to 25 ..mu..m of 26 such particles show that almost all have a dominant 10 ..mu..m silicate absorption feature. Twenty-two of the ...

Modulated spectra of CO2 (new peak at ~900 cm-1) have been received and analyzed with the purpose of comparison with spectra of martian dust and soil. It is assumed that molecules of CO2 surround the dust particles that influence on absorption and emissio

During the Apollo program the effects of lunar dust on thermal control surfaces was found to be more significant than anticipated, with several systems overheating due to deposition of dust on them. In an effort to reduce risk to future missions, a series...

To evaluate the effect of lunar dust on the optical properties (absorptivity and emissivity) of 12 candidate thermal coatings. Two duplicate arrays each ...

... DC, Woodcock, AH �The Production, Concentration, and ... of the Environment, Water, Heritage, and the ... Dust Absorption of Solar Energy." Journal of ...

... ABSORPTION SPECTRA, SOLUBILITY, AQUATIC ORGANISMS, ATOMIC PROPERTIES, SPECTRUM ANALYSIS, HARDNESS, HALF LIFE. ...

... The ether layer was dried with magnesium sulfate and then ... The Dewar flask was washed after each use with shampoo to prevent dust particles ...

The forward model will properly account for Rayleigh scattering, gaseous absorption, and the bidirectional reflection function of the surface. ...

The Saharan dust is generally found between the latitudes of 10N 20N and is ... the Earth's radiation budget through the scattering and absorption of ...

The distinct patterns, relatively low intensities, and peak positions of overtone-combination bands of silicates and oxides suggest that the 5-8 �m spectral region can provide clues for the dust composition when near optically thick conditions exist for the 10 �m silicate feature. We will present 1000-2500 cm-1 room temperature laboratory spectra ...

The distinct patterns, relatively low intensities and peak positions of overtone-combination bands of silicates and oxides suggest that the 5-8 ?m spectral region can provide clues for the dust composition when near optically thick conditions exist for the 10-?m silicate feature. We present 1000-2500 cm-1 room-temperature laboratory spectra obtained from ...

Absorption features at 6.4. keV and 7.0 keV S Unexpected ... Strong Absorption Feature. � Similar to feature observed with. Chandra ...

Scheduled for launch in summer 2011, the Interstellar Medium Absorption Gradient Experiment Rocket (IMAGER) will probe the correlation between ultraviolet dust extinction, and the metallicity and radiation environment in M101. IMAGER simultaneously images M101 in four 400�-wide bandpasses, targeting UV extinction features. We present ...

A number of authors have, in the past decade, pointed to the similarity of the 3.4-mu m band of kerogen with that of the Galactic Centre (GC). Kerogen is a family of solid terrestrial sedimentary materials essentially made of C, H and O interlocked in a disordered, more or less aliphatic, structure. Here, the most recent results of the astronomical literature and the rich quantitative geochemical ...

Using a radiative transfer code (DUSTY) parameters of the circumstellar dust shells of 15 hot post-AGB stars have been derived. Combining the optical, near and far-infrared (ISO, IRAS) data of the stars, we have reconstructed their spectral energy distributions (SEDs) and estimated the dust temperatures, mass loss rates, angular radii of the inner boundary ...

We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch ``21 mu m object'' HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model the emission of the dust we use ...

In an attempt to determine the nature of the enigmatic cocoon stars in the Quintuplet Cluster, we have obtained mid-infrared imaging and spectrophotometry of the cluster, using the CAM and SWS instruments on ISO, using SpectroCam-10 on the Palomar 5 m telescope, and NICMOS on HST. The spectra show smooth continua with various dust and ice absorption ...

Two interesting features visible through the dust are Dubai�s manmade Palm Islandsdescribed by their builders as the Eighth Wonder of the Worldin the ...

Two interesting features visible through the dust are Dubai's manmade Palm Islandsdescribed by their builders as the Eighth Wonder of the Worldin the ...

A: A dust devil is something that happens both on Earth and on Mars and looks somewhat like a mini-tornado. As with tornadoes, dust devils are spinning ...

Oct 9, 2007 ... Each type of mineral, or dust grain, has a unique signature, as can be seen in the graph, or spectrum, above. The strongest features are from ...

New measurements of the reduction of the V-band surface brightness across the prominent dust feature

Features: RIVER, DUST STORM, CHANNEL, DUST, AMUDARYA RIVER, MOUNTAIN, AGRICULTURE, VALLEY, HAZE, HINDU KUSH MTS, SEA, RANGE Geographic Region: TURKMENISTAN ...

Features: RIVER, DUST STORM, CHANNEL, DUST, AMUDARYA RIVER, MOUNTAIN, AGRICULTURE, VALLEY, HAZE, HINDU KUSH MTS, SEA, RANGE Geographic Region: TURKMENISTAN ...

Dec 5, 2003 ... Dust devils create streaks by removing or disrupting thin coatings of fine, bright, dust on the surface. These are ephemeral features that ...

Archival high-dispersion International Ultraviolet Explorer (IUE) spectra have been used to search for circumstellar gas absorption features in alpha PsA (A3 V), a nearby (6.7 pc) proto-planetary system candidate. Recent sub-millimeter mapping observations around the region of alpha PsA indicate a spatially resolved dust disk like the ...

We present spectra for a sample of 14 FUors and two T Tauri stars observed with Spitzer or ISO. Based on the appearance of the 10 ?m silicate feature, we define two categories of FUors. Objects showing the silicate feature in absorption (Category 1) are still embedded in a circumstellar envelope. The shape of the silicate bands is in ...

A mineral absorption index (MAI) has been developed to separate leaf water and mineral absorption in

Results of the initial studies of the hydrous alteration of amorphous Mg-SiO smokes indicate that although these materials readily adsorb water, the silicate structure is much more stable at 360/sup 0/K than expected. We have observed drastic changes in the relative absorption strengths of the 10- and 20-micron ''silicate'' ...

Methane explosion accidents occur frequently, and accurate and real-time detection and early warning of methane concentration are the effective means of preventing these accidents. The research was based on the spectrum absorption properties of methane, and a near-infrared tunable DFB laser diode of 1.65 microm wave band was used. With the mode-hopping ...

We have detected five (and possibly eight) weak absorption lines in the average of 14 IDS spectra of the quasar 3C 286. These optical lines have a redshift identical to the 21 cm absorption line found by Brown and Roberts at z=692. The observed lines are identified with transition in Mg I, Mg II, and Fe II. The measured equivalent widths are comparable to ...

The Discrete Ordinate Radiative Transfer (DISORT) model was used to retrieve spectral Lambert albedos from 0.4 to 4.0 ?m from Mars Express OMEGA data over layered outcrops in Aram Chaos. Atmospheric carbon dioxide, carbon monoxide, water vapor, and dust were modeled, along with both solar and thermal contributions to spectral radiances. Lambert albedos for layered units show ...

Nearly complete 2 to 13 ..mu..m spectra are presented for 13 compact infrared sources associated with molecular clouds, as well as partial spectra of six additional objects. The spectra resemble blackbodies with superposed absorption features from 2.8 to 3.5 ..mu..m, at 6.0 and 6.8 ..mu..m, and in the silicate band centered near 9.7 ..mu..m. Correlations ...

Dust-Acoustic Waves: Visible Sound Waves Robert L. Merlino Department of Physics and Astronomy and experimental work on dust acoustic waves is given. The basic physics of the dust acoustic wave and some of the theoretical refinements that have been made, including the effects of collisions, plasma absorption, ...

Infrared (IR) observations of evolved red giant stars (AGB stars) have shown that many are surrounded by dust envelopes, which are ejected into the interstellar medium and seed the next generation of stars and planets. By studying these one can understand the origins of interstellar and solar system materials. AGB stars fall into two main categories: oxygen-rich and ...

In many models of dusty objects in space the grains are assumed to be composite or fluffy. However, the computation of the optical properties of such particles is still a very difficult problem. We analyze how the increase of grain porosity influences basic features of cosmic dust - interstellar extinction, dust temperature, infrared ...

Recognition that high-mass stars form only in clusters has motivated us to make new radiative transfer models for infrared emission from compact, dense cloud cores surrounding very young high-mass stars. We assume outer cloud radii are limited by the formation of stars in clusters to 0.1 pc. Since there is a high efficiency of conversion of gas into stars within clusters, we assumed the mass of ...

Spatially resolved reflectance spectra of Mars in the 2.2- to 2.4-{mu}m spectral region were obtained in August 1988 using the NASA 3-m Infrared Telescope Facility. The spectra show weak absorption features due to Martian atmospheric carbon monoxide and a surface mineral. Both CO and the mineral absorptions are composed of overlapping ...

Our current understanding of the absorption and emission properties of interstellar grains are reviewed. The constraints placed by the Kramers-Kronig relation on the wavelength-dependence and the maximum allowable quantity of the dust absorption are discussed. Comparisons of the opacities (mass absorption ...

The mineral composition of desert dust affects global climate both radiatively and as a source of nutrients to the terrestrial and the marine ecosystems. Dust clouds strongly influence the earth�s radiative budget by absorption and scattering in both the near-UV, the visible and infrared spectral regions. In addition, in high ...

Many details of the structure of Active Galactic Nuclei (AGN) galaxies continue to elude researchers in the field. To shed light on some of the enigmas related to the fueling and classification of AGN, I have studied the core structure of a sample of 37 nearby Seyfert galaxies at high resolution using adaptive optics on the CFHT. This dataset consists of near-IR imaging from 1 to 3 ?m (the J, H, ...

Although the precise nature of interstellar dust still remains unknown after over 70 years' extensive studies since Trumpler (1930, PASP, 42, 214) first revealed its presence in interstellar space through the discovery of color excess, it is now generally accepted that interstellar grains consist of amorphous silicates and some form of carbonaceous materials; the former is ...

Aims: The interstellar medium (ISM) has a multiphase structure characterized by gas, dust, and molecules. The gas can be found in different charge states: neutral, weakly ionized (warm) and highly ionized (hot). It is possible to probe the multiphase ISM through the observation of its absorption lines and edges in the X-ray spectra of background sources. ...

The purpose of this project was to model and quantify the increase of the absorptivity of radiant barriers caused by the accumulation of dust on the surface of radiant barriers. This research was the continuation of a previous work by the author at Texas A&M University in which a radiation energy balance inside the attic enclosure was developed. The ...

Recent observations have shown that IRAS 22272+ 5435, a post-AGB object with a cool central star, is one of the few sources known which displays strong 21 and 30?m features. We present a detailed analysis of the spectral energy distribution and discuss the possible nature of the dust grains in the circumstellar envelope around this source. We find that ...

The moon Enceladus embedded in Saturn's radiation belts in the inner magnetosphere is the main internal source of charged particles in this outer planet's system. A plume of water molecules released through geysirs on the south polar region provide enough material to feed the E-ring of Saturn and the entire magnetosphere. In the time period 2005-2010 the Cassini spacecraft flew close by the moon ...

A solar terminator wave (TW) is found in high-resolution general circulation model (GCM) simulations of Mars' atmosphere. In the horizontal plane at 160 km the wave fronts follow the westward-moving dusk terminator, exhibit a horizontal wavelength of order 1800-3600 km, and are oriented about 10�-30� with respect to the terminator. The disturbance originates in the lower atmosphere due to ...

We present the first principal component analysis (PCA) applied to a sample of 119 Spitzer Infrared Spectrograph (IRS) spectra of local ultraluminous infrared galaxies (ULIRGs) at z < 0.35. The purpose of this study is to objectively and uniquely characterize the local ULIRG population using all information contained in the observed spectra. We have derived the first three principal components ...

Laboratory characterization of Interplanetary Dust Particles (IDPs) collected in the lower stratosphere represents a concrete analysis of cosmic dust properties which played a fundamental role in the origin and evolution of Solar System. The IDPs were characterized by Field Emission Scanning Electron Microscope (FESEM) analyses and by InfraRed (IR) ...

We observed asteroid (596) Scheila and its ejecta cloud using the Swift UV-optical telescope. We obtained photometry of the nucleus and the ejecta, and for the first time measured the asteroid's reflection spectrum between 290 and 500 nm. Our measurements indicate significant reddening at UV wavelengths (13% per 103 �) and a possible broad, unidentified absorption ...

The possible existence of intergalactic dust with properties similar to interstellar dust is examined in some detail. If such dust does exist, it could result in a correction to the observed deceleration parameter. (As little as 2 x 10/sup -4/ mag Mpc/sup -1/ absorption would cause a measurement error of ...

There have been several investigations of the evolution of the mid-infrared (IR) dust features in carbon star spectra based on IRAS LRS data, but these studies are somewhat contradictory. In order to understand these differences in interpretations and to develop an understanding of the carbon star dust sequence, we have reexamined 26 ...

The angular scales on which local interstellar dust is distributed are so far rather unknown as are the geometrical shapes of the dust features. From the about 5000 color excesses resulting from a north polar survey with 4 to 5 stars per square degree the...

...EVALUATION, AND APPROVAL OF MINING PRODUCTS DUST COLLECTORS FOR USE IN CONNECTION WITH ROCK DRILLING IN COAL MINES Dust-Collector Requirements § 33.23...parts of a unit that are essential to the dust-collection feature shall be...

With high-resolution infrared data becoming available that can probe the formation of high-mass stellar clusters for the first time, appropriate models that make testable predictions of these objects are necessary. We utilize a three-dimensional radiative transfer code, including a hierarchically clumped dusty envelope, to study the earliest stages of super star cluster (SSC) evolution. We explore ...

We report observational evidence for water ice in comet C/1995 O1 (Hale-Bopp) when it was at 2.9 AU from the Sun, from emission features at 44 and 65 mu m, and possibly an absorption feature at 3.1 mu m, observed with ISO/LWS and PHT. We find that icy grains have mean radii of 15 mu m within a factor of 2, lifetimes of ~ 2 days, a ...

The 10 ?m silicate feature observed with Spitzer in active galactic nuclei (AGNs) reveals some puzzling behavior. It (1) has been detected in emission in type 2 sources, (2) shows broad, flat-topped emission peaks shifted toward long wavelengths in several type 1 sources, and (3) is not seen in deep absorption in any source observed so far. We solve all ...

In places like the Mediterranean region where anthropogenic aerosols coexist with desert dust the aerosol-radiation-cloud processes are rather complicated. The mixture of different age of air pollutants of anthropogenic origin with Saharan dust and sea salt may lead to the formation of other particles with different characteristics. The mixture of the ...

We report the detection and successful modeling of the unusual 9.7 {mu}m Si-O stretching silicate emission feature in the type 1 (i.e., face-on) LINER nucleus of M81. Using the Infrared Spectrograph (IRS) instrument on Spitzer, we determine the feature in the central 230 pc of M81 to be in strong emission, with a peak at {approx}10.5 {mu}m. This ...

Dusty plasmas are ubiquitous in low-temperature laboratory discharges as well as in the near-earth environment, planetary rings, and interstellar spaces. In this paper, updated knowledge of fundamentals of collective dust-plasma interactions and several novel phenomena are presented that have been observed in laboratories and in space dusty plasmas. Mechanisms that are ...

We present the results of our ongoing study of ice evolution, dust properties and extinction in dense cores, dense clouds with varying levels of star formation activity, and young stellar objects (Chiar et al. 2007, 2011; Boogert et al. 2008, 2011). Our studies are based on 5 to 25 micron spectra from Spitzer's Infrared Spectrometer, 2 to 4 micron spectra from ground-based ...

Desert dust blows off the west coast of Africa and over the Canary Islands in this. Saharan dust. 06.20.2011. Viewed from space, the most striking feature ...

Large organic molecules and carbon clusters are basic building blocks of life, but their existence in the universe has not been confirmed beyond doubt. A number of unidentified absorption features (arising in the diffuse interstellar medium), usually called "Diffuse Interstellar Bands" (DIBs), are hypothesized to be produced by large molecules. Among ...

Mineral dust emission from the Bode�le� Depression, northern Chad, during BoDEx 2005 Martin C. Todd March 2007. [1] Mineral dust in the atmosphere is an important component of the climate system region of mineral dust into the atmosphere. Frequent dust plumes are a distinguishing feature

This National Public Radio story follows Thomas Painter, a scientist with the National Snow and Ice Data Center at the University of Colorado, as he researches the effects of dust on the Colorado Rockies snow pack. The story discusses how dust acts as a catalyst to melting snow, where the dust comes from, and explains some of the ...

We have obtained 3.2-3.6 micron spectra, with a resolution lambda/delta-lambda approximately 750, of the protostar Mon R2/IRS-3 and of Elias 16, a background K giant behind the Taurus molecular cloud. A feature at 3,482 microns (2872/cm), with a full width at half-maximum of 0.09 microns (76/cm), is clearly seen in Mon R2/IRS-3. This feature is not ...

Knowledge of the physical properties of galaxies is essential to identify the processes responsible for the emergence and evolution of galaxies. Stellar population synthesis (SPS) is the principle technique that links the observable characteristics of galaxies to their physical properties, including their star formation and chemical enrichment histories, and dust content. This ...

In a place that hadn't seen a blade of grass or a bug for ages, and contending with dust and... Read More � ASTEP � Feature Stories ...

In a place that hadn't seen a blade of grass or a bug for ages, and contending with dust and... Read More � ASTEP � Feature Stories ...

Jul 6, 2003 ... A different astronomy and space science related image is featured each day, along with a brief explanation.

In a place that hadn't seen a blade of grass or a bug for ages, and contending with dust and... Read More � ASTEP � Feature Stories ...

... of cool supergiants, are blow into space by the solar winds and are incorporated in interstellar dust of which comets probably represent a sample. ...

The solar nebula, from which the planets in our solar system formed, featured a disk of gas and dust

PAHs, dust and clouds of gas are ingredients needed for star formation. The bright feature in the very center is a cluster of stars orbiting the massive ...

Education � Video & Features � Fun Stuff & Games ...... Observations of an Urban Ocean, Stardust will bring dust particles back to ...

We report moderate resolution 3-5 {mu}m spectroscopy of the nucleus of NGC 1068 obtained at 0.''3 (20 pc) resolution with the spectrograph slit aligned approximately along the ionization cones of the active galactic nucleus. The deconvolved full width at half-maximum of the nuclear continuum source in this direction is 0.''3. Four coronal lines of widely ...

We present laboratory mid-infrared transmission/absorption spectra obtained from matrix of the hydrated Murchison CM meteorite experimentally shocked at peak pressures of 10-49 GPa, and compare them to astronomical observations of circumstellar dust in different stages of the formation of planetary systems. The laboratory spectra of the Murchison samples ...