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The detailed observations of GW170817 proved for the first time directly that neutron star mergers are a major production site of heavy elements. The observations could be fit by a number of simulations that qualitatively agree, but can quantitatively differ (e.g., in total r-process mass) by an order of magnitude. We categorize kilonova ejecta into several typical morphologies motivated by numerical simulations, and apply a radiative transfer Monte Carlo code to study how the geometric distribution of the ejecta shapes the emitted radiation. We find major impacts on both spectra and light curves. The peak bolometric luminosity can vary by two orders of magnitude and the timing of its peak by a factor of five. These findings provide the crucial implication that the ejecta masses inferred from observations around the peak brightness are uncertain by at least an order of magnitude. Mixed two-component models with lanthanide-rich ejecta are particularly sensitive to geometric distribution. A subset of mixed models shows very strong viewing angle dependence due to lanthanide curtaining, which persists even if the relative mass of lanthanide-rich component is small. The angular dependence is weak in the rest of our models, but different geometric combinations of the two components lead to a highly diverse set of light curves. We identify geometry-dependent P Cygni features in late spectra that directly map out strong lines in the simulated opacity of neodymium, which can help to constrain the ejecta geometry and to directly probe the r-process abundances.

Using the star cluster catalogs from the Hubble Space Telescope program Legacy Extragalactic UV survey (LEGUS) and 8 mu m images from the IRAC camera on the Spitzer Space Telescope for five galaxies within 5 Mpc, we investigate how the 8 mu m dust luminosity correlates with the stellar age on the 30-50 pc scale of star-forming regions. We construct a sample of 97 regions centered at local peaks of 8 mu m emission, each containing one or more young star cluster candidates from the LEGUS catalogs. We find a tight anticorrelation with a Pearson correlation coefficient ofr = -0.84 0.05 between the mass-normalized dust-only 8 mu m luminosity and the age of stellar clusters younger than 1 Gyr; the 8 mu m luminosity decreases with increasing age of the stellar population. Simple assumptions on a combination of stellar and dust emission models reproduce the observed trend. We also explore how the scatter of the observed trend depends on assumptions of stellar metallicity, polycyclic aromatic hydrocarbon (PAH) abundance, fraction of stellar light absorbed by dust, and instantaneous versus continuous star formation models. We find that variations in stellar metallicity have little effect on the scatter, while PAH abundance and the fraction of dust-absorbed light bracket the full range of the data. We also find that the trend is better explained by continuous star formation, rather than instantaneous burst models. We ascribe this result to the presence of multiple star clusters with different ages in many of the regions. Upper limits of the dust-only 8 mu m emission as a function of age are provided.

The physical evolution of young stellar objects (YSOs) is accompanied by an enrichment of the molecular complexity, mainly triggered by the heating and energetic processing of astrophysical ices. In this paper, a study of how the ice column density varies across the protostellar evolution has been performed. Tabulated data of H2O, CO2, CH3OH, and HCOOH observed by ground- and space-based telescopes toward 27 early-stage YSOs were taken from the literature. The observational data show that ice column density and spectral index (alpha), used to classify the evolutionary stage, are well correlated. A 2D continuum radiative transfer simulation containing bare and ice-covered grains at different levels of cosmic-ray processing were used to calculate the spectral energy distributions in different angle inclinations between face-on and edge-on configurations. The H2O:CO(2)ice mixture was used to address the H2O and CO(2)column density variation, whereas CH3OH and HCOOH are by-products of the virgin ice after energetic processing. The simulated spectra were used to calculate the ice column densities of YSOs in an evolutionary sequence. As a result, the models show that the ice column density variation of HCOOH with alpha can be justified by envelope dissipation and energetic processing of ice. On the other hand, the ice column densities are mostly overestimated in the cases of H2O, CO(2)and CH3OH, even though the physical and cosmic-ray processing effects are taken into account.

Colloidal quantum dot (CQD) light-emitting diodes (LEDs) deliver a compelling performance in the visible, yet infrared CQD LEDs underperform their visible-emitting counterparts, largely due to their low photoluminescence quantum efficiency. Here we employ a ternary blend of CQD thin film that comprises a binary host matrix that serves to electronically passivate as well as to cater for an efficient and balanced carrier supply to the emitting quantum dot species. In doing so, we report infrared PbS CQD LEDs with an external quantum efficiency of ~7.9% and a power conversion efficiency of ~9.3%, thanks to their very low density of trap states, on the order of 1014 cm−3, and very high photoluminescence quantum efficiency in electrically conductive quantum dot solids of more than 60%. When these blend devices operate as solar cells they deliver an open circuit voltage that approaches their radiative limit thanks to the synergistic effect of the reduced trap-state density and the density of state modification in the nanocomposite., Peer Reviewed, Postprint (author's final draft)

InAs/GaAs quantum dot devices have the potential to be the leading technology for infrared detection and emission which are necessary for many military and domestic applications. Quantum dot infrared photodetectors yield higher operating temperatures, lower dark currents, and more wavelength tunability. They also permit the detection of normal-incidence light. Quantum dot infrared sources are also expected to yield higher operating temperatures, ln addition to lower threshold currents and higher modulation bandwidths. After a brief review of the history of infrared detection and emission, the optical and electrical characteristics of self-organized In(Ga)As/GaAs quantum dots grown by molecular beam epitaxy are discussed, followed by results for the quantum dot detectors and emitters that have been developed at the University of Michigan, Ann Arbor., Published in the International Journal of High Speed Electronics and Systems, v12 n4 p969-994, 2002. Supported in part by DARPA.

Infrared survey measurements obtained from two probeborne experiments flown in 1982 combined with extensive ground-based observations on AFGL sources are incorporated into a revised AFGL Four Color Infrared Survey catalog. Over 92 percent of the sky has been covered at 11 and 20 micron, 71 percent at 4 micron and 47 percent at high sensitivity at 27 micron. There are 2970 entries in the main catalog, most of which are multicolor observations. The catalog contents are resolved into two general groups: a disk population (slope= 0.4) with means colors m (11)-m(20)=2.0 and m(20)-m(27)=0.9 corresponding to color temperatures of 270K and 185K, respectively, and a spherical distribution (slope = 0.6) with a mean color difference of m(11)-m(20)=1.0 corresponding to T sub c approx = 10 480K.

The patent relates generally to the field of infrared radiation and, in particular, to a novel means for maintaining the output from an airborne-type of infrared radiation source at a relatively high level., Supersedes AD-D000 357.

The concept of continuously tunable far infrared sources was investigated in magnetically and electrically tunable level systems. Landau emission has been investigated in several semiconductors. A useful source for spectroscopic investigations based on bulk GaAs with a resolution below 1 per cm has been developed in the spectral range from 20 to 120 per cm. New promising concepts for tunable sources have been demonstrated recently: A significant line narrowing of the Landau emission was observed from InSb under the presence of hydrostatic pressure above 8 kbar. For the first time tunable emission from spin-flip transitions in uniaxially stressed InSb was observed. Linewidths in the order of 0.2 per cm are found which opens the potential for high resolution spectroscopy with magnetically tunable sources. For the realization of voltage tunable sources based on the voltage tunable electron density in MOS-devices, three possible mechanisms were investigated: The radiative recombination between electric subbands, between minigaps induced by tilted interfaces in respect to the main cristallographic directions and the radiative decay of two-dimensional plasma-oscillations via periodic grating structures.

We report infrared positions and multicolor infrared photometry for a sample of type II OH/IR stars. The infrared colors and 11.4 -micrometer silicate optical depths of the low-latitude sources in this group increase as a function of distance, suggesting that interstellar reddening must be taken into account in assessing their infrared energy distributions. Redding gradients between 1 and 3 times higher than the mean gradient in the direction of the galactic center are required to account for the observed color-distance correlation, a fact which might be explained by these stars' confinement to spiral arms. The noise limited magnitudes for the AFGL Infrared Sky Survey have been estimated by direct comparison with ground based observations. Using these limiting magnitudes pruned versions of teh AFGL catalog have been generated. Infrared observations of all the stellar objects seen at 11, 20 or 27 micrometers and a statistical sample of the stars seen only at 4 micrometers are reported. Analysis of the observations leads to estimates of the absolute 4 and 10 micrometers magnitudes and space densities for the two classes of objects. The expected results from the Infrared Astronomical Satellite are re-examined. (Author)

This final report gives an account of work performed since the interim report. The report is divided into two parts. Part I covers the consolidation, refinement, and increased versatility of empirical computer programs over initial efforts in the field of prediction of radiation patterns from shielded infrared sources. Part II presents the development of an analytical approach for the evaluation of shield configurations for infrared sources. This approach employs a set of complex integral equations relating shield geometry and radiative characteristics of the source to angular distribution of radiative energy., See also AD-426 787

The report presents results of measuring the intensity of infrared radiation from a source with a working surface 500X500 mm in the interval of temperatures -40 to +50C., Trans. of Optiko-Mekhanicheskaya Promyshlennost (USSR) v39 n7 p66-67 1972.