Measuring the Optical Properties of Astrophysical Dust Analogues: Instrumentation and Methods

Dust is found throughout the universe and plays an important role for a wide range of astrophysical phenomena. In recent years, new infrared facilities have provided powerful new data for understanding these phenomena. However, interpretation of these data is often complicated by a lack of complementary information about the optical properties of astronomically relevant materials. The Optical Properties of Astronomical Silicates with Infrared Techniques (OPASI-T) program at NASA's Goddard Space Flight Center is designed to provide new high-quality laboratory data from which we can derive the optical properties of astrophysical dust analogues. This program makes use of multiple instruments, including new equipment designed and built specifically for this purpose. The suite of instruments allows us to derive optical properties over a wide wavelength range, from the near-infrared through the millimeter, also providing the capability for exploring how these properties depend upon the temperature of the sample. In this paper, we discuss the overall structure of the research program, describe the new instruments that have been developed to meet the science goals, and demonstrate the efficacy of these tools

FTIR MATRIX AND DFT STUDY OF THE VIBRATIONAL SPECTRUM OF NiC3_3Ni

Author Institution: Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129\maketitle This study of NiC$_3$Ni is part of continuing Fouriertransform infrared (FTIR) and density functional theory (DFT) research investigating the structures and vibrations of small transition-metal carbide clusters. These studies are motivated by the potential for identifying metal carbide species in astrophysical environments and interest in understanding their role in the formation and bonding mechanisms of larger transition-metal carbide structures such as metallocarbohedrenes. FTIR spectra of NiC$_3$Ni were obtained by trapping the vapors produced during dual ablation of $^{13}$C-enriched graphite and Ni rods with Nd:YAG lasers in solid Ar at $\sim$10 K. An asymmetric carbon stretching mode of NiC$_3$Ni has been observed at 1950.8 $\pm$ 0.2 \wn. The measured isotopic shifts are in good agreement with shifts calculated using DFT simulations. Although other small nickel-carbon clusters have been the subject of considerable theoretical research} \underline{\textbf{68}}, 167401 (2003).}, this is the first report on NiC$_3$Ni

The Ethnographer’s Apprentice: Trying Consumer Culture from the Outside In

anthropology, consumerism, ethnography, globalization, marketing,

Eye-Size Variability in Deep-Sea Lanternfishes (Myctophidae): An Ecological and Phylogenetic Study

One of the most common visual adaptations seen in the mesopelagic zone (200-1000 m), where the amount of light diminishes exponentially with depth and where bioluminescent organisms predominate, is the enlargement of the eye and pupil area. However, it remains unclear how eye size is influenced by depth, other environmental conditions and phylogeny. In this study, we determine the factors influencing variability in eye size and assess whether this variability is explained by ecological differences in habitat and lifestyle within a family of mesopelagic fishes characterized by broad intra-and interspecific variance in depth range and luminous patterns. We focus our study on the lanternfish family (Myctophidae) and hypothesise that lanternfishes with a deeper distribution and/or a reduction of bioluminescent emissions have smaller eyes and that ecological factors rather than phylogenetic relationships will drive the evolution of the visual system. Eye diameter and standard length were measured in 237 individuals from 61 species of lanternfishes representing all the recognised tribes within the family in addition to compiling an ecological dataset including depth distribution during night and day and the location and sexual dimorphism of luminous organs. Hypotheses were tested by investigating the relationship between the relative size of the eye (corrected for body size) and variations in depth and/or patterns of luminous-organs using phylogenetic comparative analyses. Results show a great variability in relative eye size within the Myctophidae at all taxonomic levels (from subfamily to genus), suggesting that this character may have evolved several times. However, variability in eye size within the family could not be explained by any of our ecological variables (bioluminescence and depth patterns), and appears to be driven solely by phylogenetic relationships