Large Amounts Of Dust Research Articles

Extended Emission by Dust in the Dwarf Galaxy UGC 10445

We present Spitzer Space Telescope images of the isolated dwarf galaxy UGC 10445. The galaxy is detected at all photometric bands (3.6-160 μm), as well as in the Multiband Imaging Photometer for Spitzer (MIPS) spectral energy distribution mode (55-95 μm). We derive a star formation rate of 0.25 M☉ yr-1, based on Hα and infrared flux densities. There is over 106 M☉ of cold dust (T ~ 18 K) in the galaxy, represented by 160 μm emission, which extends to a larger radius than the ultraviolet (UV), optical, and near-infrared light. Such extended emission has been seen previously only in dwarf galaxies in cluster environments. We suggest that the source of heating for this dust is UV light, originating in star-forming complexes. To produce the large quantity of dust requires a higher rate of star formation in the past than is currently observed.

Saharan dust intrusions in the Mediterranean area: Three years of Raman lidar measurements

A multiyear climatological study of Saharan dust intrusions in the central Mediterranean in terms of aerosol optical parameters vertical profiles is carried out for the first time. Observations are performed at Istituto di Metodologie per l'Analisi Ambientale (IMAA) Raman/elastic lidar station located in Tito Scalo, Potenza (40°36′N, 15°44′E), from May 2000 to April 2003, in the framework of European Aerosol Research Lidar Network (EARLINET). Desert dust aerosols are observed between 1.8 and 9 km in 112 days. Mean values within the desert dust layer of 76 Mm−1, 1.0 Mm−1 sr−1 and 0.54 Mm−1 sr−1 are observed for aerosol extinction at 355 nm and aerosol backscatter at 355 and 532 nm. Desert dust layer optical depth at 355 nm ranges between 0.001 and 0.68, with a mean of 0.13. The source origin is the central Sahara in about 65% of the cases, the western Sahara in about 31%, and only in four cases the eastern Sahara. The most extended database of Saharan dust lidar ratio data was collected: Values range between 6 and 126 sr following a 3‐modal Gaussian distribution centered at 22, 37 and 57 sr. A mean value of 37 sr is found around the center of the Saharan dust layer. At its extremes, where dust particles are mixed to PBL and free troposphere background aerosols, a mean value of 57 sr is found. Finally, low lidar ratio values of about 22 sr are observed when large amount of dust is transported at low altitudes over the Mediterranean Sea.

Ultraviolet-to-far infrared properties of Lyman break galaxies and luminous infrared galaxies at z ~ 1

We present the first large, unbiased sample of Lyman Break Galaxies (LBGs) at z ~ 1. Far ultraviolet-dropout (1530 A) galaxies in the Chandra Deep Field South have been selected using GALEX data. This first large sample in the z ~ 1 universe provides us with a high quality reference sample of LBGs. We analyzed the sample from the UV to the IR using GALEX, SPITZER, ESO and HST data. The morphology (obtained from GOODS data) of 75 % of our LBGs is consistent with a disk. The vast majority of LBGs with an IR detection are also Luminous Infrared Galaxies (LIRGs). As a class, the galaxies not detected at 24 microns are an order of magnitude fainter relative to the UV compared with those detected individually, suggesting that there may be two types of behavior within the sample. For the IR-bright galaxies, there is an apparent upper limit for the UV dust attenuation and this upper limit is anti-correlated with the observed UV luminosity. Previous estimates of dust attenuations based on the ultraviolet slope are compared to new ones based on the FIR/UV ratio (for LBGs detected at 24 microns), which is usually a more reliable estimator. Depending on the calibration we use to estimate the total IR luminosity, beta-based attenuations A_{FUV} are larger by 0.2 to 0.6 mag. than the ones estimated from FIR/UV ratio. Finally, for IR-bright LBGs, median estimated beta-based SFRs are 2-3 times larger than the total SFRs estimated as SFR_{TOT} = SFR_{UV} + SFR_{IR} while IR-based SFRs provide values below SFR_{TOT} by 15 - 20 %. We use a stacking method to statistically constrain the 24 microns flux of LBGs non individually detected. The results suggest that these LBGs do not contain large amounts of dust.

Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles

Sea ice and dust flux increased greatly in the Southern Ocean during the last glacial period. Palaeorecords provide contradictory evidence about marine productivity in this region, but beyond one glacial cycle, data were sparse. Here we present continuous chemical proxy data spanning the last eight glacial cycles (740,000 years) from the Dome C Antarctic ice core. These data constrain winter sea-ice extent in the Indian Ocean, Southern Ocean biogenic productivity and Patagonian climatic conditions. We found that maximum sea-ice extent is closely tied to Antarctic temperature on multi-millennial timescales, but less so on shorter timescales. Biological dimethylsulphide emissions south of the polar front seem to have changed little with climate, suggesting that sulphur compounds were not active in climate regulation. We observe large glacial-interglacial contrasts in iron deposition, which we infer reflects strongly changing Patagonian conditions. During glacial terminations, changes in Patagonia apparently preceded sea-ice reduction, indicating that multiple mechanisms may be responsible for different phases of CO2 increase during glacial terminations. We observe no changes in internal climatic feedbacks that could have caused the change in amplitude of Antarctic temperature variations observed 440,000 years ago.

Gemini Near Infrared Spectrograph Observations of the Central Supermassive Black Hole in Centaurus A

The Gemini Near Infrared Spectrograph on Gemini South unlocks new possibilities to study the central black holes (BHs) in dusty galaxies that have been inaccessible to previous BH studies. We exploit good near-infrared seeing to measure the central BH of Centaurus A (NGC 5128). We measure the stellar kinematics of NGC 5128 using the region around the CO band heads at 2.3 μm and determine the BH mass using axisymmetric orbit-based models. BHs are believed to be essential components of galaxies, and their evolutionary states appear to be closely linked to those of their hosts. Our current knowledge does not go much beyond this; galaxies such as NGC 5128 (a recent merger with an active galactic nucleus) can further develop this knowledge. However, NGC 5128 and galaxies like it contain large amounts of dust, which hamper optical spectroscopy, making near-infrared measurements an attractive alternative. We find a BH mass of 2.4 × 108 M⊙ for an edge-on model, 1.8 × 108 M⊙ for a model with an inclination of 45°, and 1.5 × 108 M⊙ for a model with an inclination of 20°. We adopt the value for the edge-on model, since it has significantly lower χ2; however, it is unlikely that we can constrain the actual inclination of moderately triaxial NGC 5128 using an axisymmetric modeling procedure. These estimates, based on adjusting the asymmetric kinematics of NGC 5128 so that we can use an axisymmetric code, are consistent with the range of acceptable BH masses implied by a previous gas dynamical study. However, these estimates are 5–10 times higher than that predicted by the correlation between BH mass and velocity dispersion. If NGC 5128 will eventually follow the trend for quiescent galaxies, this result suggests that its BH assembled first before its host component. NGC 5128 thus provides an important example for our knowledge of central BHs; this technique can be applied to other such galaxies to further explore this question.

Obscured Activity: AGN, Quasars, Starbursts and ULIGs Observed by the Infrared Space Observatory

Some of the most ‘active’ galaxies in the Universe are obscured by large quantities of dust and emit a substantial fraction of their bolometric luminosity in the infrared. Observations of these infrared luminous galaxies with the Infrared Space Observatory (ISO) have provided a relatively unabsorbed view to the sources fuelling this active emission. The improved sensitivity, spatial resolution and spectroscopic capability of ISO over its predecessor Infrared Astronomical Satellite (IRAS) of enabled significant advances in the understanding of the infrared properties of active galaxies. ISO surveyed a wide range of active galaxies which, in the context of this review, includes those powered by intense bursts of star formation as well as those containing a dominant active galactic nucleus (AGN). Mid-infrared imaging resolved for the first time the dust enshrouded nuclei in many nearby galaxies, while a new era in infrared spectroscopy was opened by probing a wealth of atomic, ionic and molecular lines as well as broad band features in the mid- and far-infrared. This was particularly useful, since it resulted in the understanding of the power production, excitation and fuelling mechanisms in the nuclei of active galaxies including the intriguing but so far elusive ultraluminous infrared galaxies. Detailed studies of various classes of AGN and quasars greatly improved our understanding of the unification scenario. Far-infrared imaging and photometry revealed the presence of a new very cold dust component in galaxies and furthered our knowledge of the far-infrared properties of faint starbursts, ULIGs and quasars. We summarise almost nine years of key results based on ISO data spanning the full range of luminosity and type of active galaxies.

Mission Concept for the Single Aperture Far-Infrared (SAFIR) Observatory

The Single Aperture Far-InfraRed (SAFIR) Observatory’s science goals are driven by the fact that the earliest stages of almost all phenomena in the universe are shrouded in absorption by and emission from cool dust and gas that emits strongly in the far-infrared (40μ–200μ) and submillimeter (200μ–1 mm). In the very early universe, the warm gas of newly collapsing, unenriched galaxies will be revealed by molecular hydrogen emission lines at these long wavelengths. High redshift quasars are found to have substantial reservoirs of cool gas and dust, indicative of substantial metal enrichment early in the history of the universe. As a result, even early stages of galaxy formation will show powerful far-infrared emission. The combination of strong dust emission and large redshift (1 < z < 7) of these galaxies means that they can only be studied in the far-infrared and submillimeter. For nearby galaxies, many of the most active galaxies in the universe appear to be those whose gaseous disks are interacting in violent collisions. The details of these galaxies, including the effect of the central black holes that probably exist in most of them, are obscured to shorter wavelength optical and ultraviolet observatories by the large amounts of dust in their interstellar media. Within our own galaxy, the earliest stages of star formation, when gas and dust clouds are collapsing and the beginnings of a central star are taking shape, can only be observed in the far-infrared and submillimeter. The cold dust that ultimately forms the planetary systems, as well as the cool “debris” dust clouds that indicate the likelihood of planetary sized bodies around more developed stars, can only be observed at wavelengths longward of 20μ.

The ventilation of an underground crushing plant

The use of compressive crushing plant such as gyratory crushers within minerals processing operations can generate large quantities of dust as large volumes of ore are tipped into the crusher feed bins. Methods to reduce these dust emissions include the retrofitting of shrouds, enclosures, local exhaust ventilation (LEV) systems and water suppression systems. The operation of these ancillary systems should be optimised to offer maximum performance. It is desirable that the future planning of such facilities include sufficient dust suppression and/or removal systems to ensure that material delivery rates are maintained and the welfare of the workforce is protected. This paper presents the results of an investigation of the tipping process through the application of computational fluid dynamic (CFD) methods and validation using data obtained from scale experiment. A 3-D computational model has been constructed using the Fluent™ <www. fluent. co. uk> modelling software to represent the ventilation regimen within an underground crushing installation. The falling ore has been represented as a granular fluid continuum falling under gravity from the bed of the dump truck. Transient streamlines are used to represent the dispersion of dust due to the updraft airflow generated by the tipping process. A parametric analysis has been performed on a model of the tipping process to investigate the influence on dust dispersion of; the orientation of the dump truck, the surrounding ventilation characteristics and the material tipping rate and volume. The CFD models predict a strong shear-induced flow in the region of the crusher during tipping and a high sensitivity to the surrounding ventilation regimen. These results indicate the need for further experimental studies to characterise the entrainment and transport of dust-laden air into the induced shear flow. An experimental rig has been designed and evaluated for the purposes of conducting validation studies and gaining further insight into this phenomenon. Results of these investigations are presented.

Multicolor CCD photometry of the dusty, giant, late-type spiral galaxy NGC 5351

The paper reports the results of BV RI surface photometry of the giant galaxy NGC 5351 based on CCD observations obtained on the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. Analysis of the structure and radial brightness distribution in the galaxy shows that NGC 5351 has a complex and, in some places, asymmetric structure. The galaxy possesses a large quantity of dust. The average internal extinction due to dust is AV=1.2m±0.4m. After correcting for the effect of this dust, the parameters of the galaxy are typical of late-type spirals. The compositions of the stellar population in various parts of the galaxy are estimated using two-color diagrams. Star-forming regions in NGC 5351 are identified and studied. Most of the star-forming regions are located in the ring of the galaxy. Evolutionary modeling is used to estimate the ages of regions of violent star formation. An elliptical companion galaxy to NGC 5351 was found. The rotation curve of the galaxy is modeled and its mass estimated. The disk of NGC 5351 is self-gravitating within its optical radius.

Comparisons of the Dust/Smoke Particulate that Settled Inside the Surrounding Buildings and Outside on the Streets of Southern New York City after the Collapse of the World Trade Center, September 11, 2001

The collapse of the World Trade Center (WTC) on September 11, 2001, generated large amounts of dust and smoke that settled in the surrounding indoor and outdoor environments in southern Manhattan. Sixteen dust samples were collected from undisturbed locations inside two uncleaned buildings that were adjacent to Ground Zero. These samples were analyzed for morphology, metals, and organic compounds, and the results were compared with the previously reported outdoor WTC dust/smoke results. We also analyzed seven additional dust samples provided by residents in the local neighborhoods. The morphologic analyses showed that the indoor WTC dust/smoke samples were similar to the outdoor WTC dust/smoke samples in composition and characteristics but with more than 50% mass in the <53 μm size fraction. This was in contrast to the outdoor samples that contained >50% of mass above >53 μm. Elemental analyses also showed the similarities, but at lower concentrations. Organic compounds present in the outdoor samples were also detected in the indoor samples. Conversely, the resident-provided convenience dust samples were different from either the WTC indoor or outdoor samples in composition and pH, indicating that they were not WTC-affected locations. In summary, the indoor dust/smoke was similar in concentration to the outdoor dust/smoke but had a greater percentage of mass <53 μm in diameter.

Blue Blob in the Red Rectangle

ASTROPHYSICS The Red Rectangle nebula is an unusual protoplanetary nebula. Its central star, HD44179, is dying, and substantial mass is being blown off the star in a bipolar outflow, creating the rectangular shape and a large amount of dust. It is the brightest source of unidentified infrared band emission (UIR), and much of this comes from carbon compounds. Given that 20 to 30% of the Milky Way's infrared radiation is in the UIR and that carbon is an important component of stars, planets, and terrestrial life, it is desirable to identify the carbon species that account for the emissions. At shorter wavelengths, in the visible to ultraviolet, the Red Rectangle looks like a blue blob, produced by dust-scattered light from the central star. Vijh et al. obtained spectra at these wavelengths, and the peaks correspond to those in fluorescence spectra of electronic transitions in neutral polycyclic aromatic hydrocarbons (PAHs) with three to four rings, such as anthracene and pyrene. Thus, not only is the Red Rectangle producing a lot of PAH dust, but blue luminescence may be used to identify many carbon and silicon species that fluoresce at specific wavelengths. — LR Astrophys. J. , in press (astro-ph/0403522).

A Quaternary climate record based on grain size analysis from the Luochuan loess section on the Central Loess Plateau, China

Important climatic information is stored in the Luochuan sediment record on the Central Loess Plateau in China. Large quantities of dust have registered the activity of the summer and winter monsoon. In this paper, the process that caused the loess deposition is explained and the influence of (palaeo)climate on this sedimentation process is discussed. The concept of establishing a time scale is based on the fact that grain size and sedimentation rate (SR) appear to correlate very well with the strength of the winter monsoon in northern China. Grain-size analysis does not only offer the opportunity to construct an independent numerical Quaternary time scale, but also to reconstruct temporal palaeoclimatic changes. In a reference curve, the correlation between grain size and SR is determined, afterwards the SR of all layers could be calculated based on their grain size. In this work, the climatic results of the Luochuan loess section are determined by making two important adjustment steps. Firstly, a general grain-size trend has been removed since the layers tend to coarsen upwards in the section. Secondly, the real quantity of sediment deposited is calculated by multiplying the SR with the bulk density of the layer, which results in dust flux values. The bulk density of the loess layers appears to fluctuate both in depth as well as with palaeoclimate during dust deposition. Finally, climatic results derived from this improved time scale are discussed.

Dust production in supernovae

The question `Are supernovae important sources of dust?' is a contentious one. Condensation theory and observations of dust at very high redshifts suggests that they should be, since only massive stars evolve quickly enough to produce the large quantities of dust seen at such early times in the Universe. However, observations with IRAS and ISO have only detected very small amounts of hot dust in supernova remnants, not enough to make them significant sources of dust. Here, we present new observations of two young Galactic remnants with SCUBA, and show that large quantities of dust are indeed produced by supernovae.

Age Dependence of the Vega Phenomenon: Theory

In a separate paper (Decin et al 2003), we have re-examined the observations of IR excess obtained with the ISO satellite and discussed the ages of stars with excess. The amount of dust (measured by the luminosity fraction \fdust=L_\mathrm{IR}/L_{\star}) seen around main-sequence stars of different ages shows several interesting trends. To discuss these results in the context of a physical model, we develop in this paper an analytical model for the dust production in Vega-type systems. Previously it has been claimed that a powerlaw slope of about -2 in the diagram plotting amount of dust versus time could be explained by a simple collisional cascade. We show that such a cascade in fact results in a powerlaw \fdust\propto t^{-1} if the dust removal processes are dominated by collisions. A powerlaw \fdust\propto t^{-2} only results when the dust removal processes become dominated by Pointing-Robertson drag. This may be the case in the Kuiper Belt of our own solar system, but it is certainly not the case in any of the observed disks. A steeper slope can, however, be created by including continuous stirring into the models. We show that the existence of both young and old Vega-like systems with large amounts of dust (\fdust\simeq 10^{-3}) can be explained qualitatively by Kuiper-Belt-like structures with \emph{delayed stirring}. Finally, the absence of young stars with intermediate amounts of dust may be due to the fact that stirring due to planet formation may not be active in young low-mass disks. The considerations in this paper support the picture of simultaneous stirring and dust production proposed by Kenyon and Bromley (2002).

Type II supernovae as a significant source of interstellar dust.

Large amounts of dust (>10(8)M(o)) have recently been discovered in high-redshift quasars and galaxies corresponding to a time when the Universe was less than one-tenth of its present age. The stellar winds produced by stars in the late stages of their evolution (on the asymptotic giant branch of the Hertzsprung-Russell diagram) are thought to be the main source of dust in galaxies, but they cannot produce that dust on a short enough timescale (&<1 Gyr) to explain the results in the high-redshift galaxies. Supernova explosions of massive stars (type II) are also a potential source, with models predicting 0.2-4M(o) of dust. As massive stars evolve rapidly, on timescales of a few Myr, these supernovae could be responsible for the high-redshift dust. Observations of supernova remnants in the Milky Way, however, have hitherto revealed only 10(-7)-10(-3)M(o) each, which is insufficient to explain the high-redshift data. Here we report the detection of approximately 2-4M(o) of cold dust in the youngest known Galactic supernova remnant, Cassiopeia A. This observation implies that supernovae are at least as important as stellar winds in producing dust in our Galaxy and would have been the dominant source of dust at high redshifts.

SCUBA observations of NGC 1275

Deep SCUBA observations of NGC 1275 at 450 micron and 850 micron along with the application of deconvolution algorithms have permitted us to separate the strong core emission in this galaxy from the fainter extended emission around it. The core has a steep spectral index and is likely due primarily to the AGN. The faint emission has a positive spectral index and is clearly due to extended dust in a patchy distribution out to a radius of $\sim$ 20 kpc from the nucleus. These observations have now revealed that a large quantity of dust, $\sim$ 6 $\times$ 10$^7$ $M_\odot$, 2 orders of magnitude larger than that inferred from previous optical absorption measurements, exists in this galaxy. We estimate the temperature of this dust to be $\sim$ 20 K (using an emissivity index of $\beta$ = 1.3) and the gas/dust ratio to be 360. These values are typical of spiral galaxies. The dust emission correlates spatially with the hot X-ray emitting gas which may be due to collisional heating of broadly distributed dust by electrons. Since the destruction timescale is short, the dust cannot be replenished by stellar mass loss and must be externally supplied, either via the infalling galaxy or the cooling flow itself.

Keck Observations of the Hidden Quasar IRAS P09104+4109

We present imaging and spectropolarimetric observations of the ultraluminous infrared galaxy IRAS P09104+4109 using the Keck 10 m Telescope. We detect the clear presence of broad Hβ, Hγ, and Mg II λ2800 emission lines in the polarized flux spectra of the nucleus and of an extranuclear emission region ~4'' away, confirming the presence of a hidden central quasar. The polarization of the broad Mg II emission line is high (~29%), consistent with the remarkably high polarization (~30%–40%) observed in the extended continuum emission. This indicates that the off-nuclear continuum is dominated by light scattered from the hidden quasar, most probably by dust mixed with the line-emitting gas. The high polarizations, combined with the foreshortened morphology of the polarized brightness distribution, allow us to constrain the scattering biconical structure to be at inclination i ≈ 50° with a half-opening cone angle θc ≈ 40°. The narrow emission lines are polarized in a stratified fashion, with the high-ionization lines ([O III], [Ne V], [Fe VII]) being polarized 0.7%–1.7% and [O II] essentially unpolarized. The line polarizations are positively correlated with critical density, ionization potential, and velocity width of the emission lines. This indicates that, as is the case with the narrow-line radio galaxies, which also often contain powerful quasars, the narrow emission line region may be partially shadowed by the putative torus, with the higher ionization lines originating closer to the nucleus. One notable characteristic of the extranuclear knot is that all species of Fe are markedly absent in its spectrum, while they appear prominently in the nucleus. In addition, narrow Mg II is observed to be much weaker than predicted by ionization models. Our favored interpretation is that there is a large amount of dust in the extranuclear regions, allowing gaseous refractory metals to deposit. Near the nucleus, dust is destroyed in the strong radiation field of the quasar, inhibiting metal depletion onto grains. The extended emission regions are most likely material shredded from nearby cluster members and not gas condensed from the cooling flow or expelled from the obscured quasar. The higher temperature inferred from [O III] lines compared to that from [N II] and the general better agreement with models of line ratios, especially [O III] λ5007/λ4363 and He II/Hβ, provide strong evidence for matter-bounded clouds in addition to ionization-bounded clouds in the narrow-line region. Ionization by pure velocity shocks can be ruled out. Shocks with photoionizing precursors may be present but are probably not a dominant contributor to the energy input.

Dust formation and inhomogeneous mass-loss from asymptotic giant branch stars

ABSTRA C T We examine the flow from asymptotic giant branch (AGB) stars when along a small solid angle the optical depth resulting from dust is very large. We consider two types of flows. In the first, small cool spots are formed on the surface of slowly rotating AGB stars. Large quantities of dust are expected to be formed above the surface of these cool spots. We propose that if the dust formation occurs during the last AGB phase when the mass-loss rate is high, the dust shields the region above it from the stellar radiation. This leads to both further dust formation in the shaded region and, owing to lower temperature and pressure, the convergence of the stream toward the shaded region, and the formation of a flow having a higher density than its surroundings. This density contrast can be as high as ,4. A concentration of magnetic cool spots toward the equator will lead to a density contrast of up to a few between the equatorial and polar directions. This process can explain the positive correlation between high mass-loss rate and a larger departure from sphericity in progenitors of elliptical planetary nebulae. In the second type of flow, the high density in the equatorial plane is formed by a binary interaction, where the secondary star is close to, but outside the AGB envelope. The shielding of the radiation by dust results in a very slow and dense flow in the equatorial plane. We suggest this flow as an alternative explanation for the equatorial dense matter found at several hundred astronomical units around several post-AGB binary

A soiling system for evaluation of house dust, allergens, and lead retention on carpets and other surfaces.

Artificial soiling of carpeted or other floor surfaces has several important applications in human exposure assessment and textile research including evaluation of textile properties, sampling devices, and cleaning regimens. A method was developed and validated to deposit uniform and reproducible known quantities of house dust, allergens, and leaded dust on carpets. The soiling apparatus consisted of a 100 cm x 60 cm inclined steel track and a plastic cylinder, with a series of staggered holes, that contains a known volume of reference house dust. After deposition, the dust is embedded by dragging a steel rod over the carpet surface. Deposition tests were performed with bulk house dust, sodium chloride, and house dust with reference quantities of dust mite allergen and lead. The apparatus deposited equivalent (arithmetic mean) amounts of dust, sodium chloride, and dust mite allergen on the front and back halves of test carpets. The introduction of inert fumed silica to the reference sample aided in dispersal of dust over test surfaces. Little to no variation in mean deposition was found within or between 4 days of testing. Using a grid containing weighing boats under the apparatus, spatial deposition was found to vary across a 92 x 46 cm surface by 13 percent. The apparatus deposited reproducible mean quantities of bulk dust on test surfaces from 7 g/m2 to 28 g/m2 with a coefficient of variation ranging from 4-6 percent. The apparatus could be altered to deliver smaller or larger amounts of dust.

The Gravitational Lens MG 0414+0534: A Link between Red Galaxies and Dust

We present near-IR observations of the red gravitational lens system MG 0414+0534. Our images are of sufficient quality to allow photometry of all four QSO images and the lens galaxy. The observations show that the K-band brightnesses of the components are more similar to the radio brightnesses than to the optical and thus support the notion that the system is highly reddened. The differing brightnesses at visible wavelengths are interpreted as variable amounts of extinction in the lens galaxy. The lens galaxy is detected in the K band and is as red as any other known galaxy of comparable apparent magnitude. An estimate of the redshift of the lens galaxy of 0.45 < z < 0.6 is determined from the Faber-Jackson relation and photometric considerations. By extension, we argue that other very red field galaxies may contain large amounts of dust. K-band spectra of the individual components show no difference in the Hα equivalent widths among the components. This is evidence against significant microlensing.