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Measurements in the infrared wavelength domain allow direct assessment of the physical state and energy balance of cool matter in space, enabling the detailed study of the processes that govern the formation and evolution of stars and planetary systems in galaxies over cosmic time. Previous infrared missions revealed a great deal about the obscured Universe, but were hampered by limited sensitivity.
SPICA takes the next step in infrared observational capability by combining a large 2.5-meter diameter telescope, cooled to below 8 K, with instruments employing ultra-sensitive detectors. A combination of passive cooling and mechanical coolers will be used to cool both the telescope and the instruments. With mechanical coolers the mission lifetime is not limited by the supply of cryogen. With the combination of low telescope background and instruments with state-of-the-art detectors SPICA provides a huge advance on the capabilities of previous missions.
SPICA instruments offer spectral resolving power ranging from R ~50 through 11 000 in the 17–230 μm domain and R ~28.000 spectroscopy between 12 and 18 μm. SPICA will provide efficient 30–37 μm broad band mapping, and small field spectroscopic and polarimetric imaging at 100, 200 and 350 μm. SPICA will provide infrared spectroscopy with an unprecedented sensitivity of ~5 × 10−20 W m−2 (5σ/1 h)—over two orders of magnitude improvement over what earlier missions. This exceptional performance leap, will open entirely new domains in infrared astronomy; galaxy evolution and metal production over cosmic time, dust formation and evolution from very early epochs onwards, the formation history of planetary systems.
Dietary deficiencies in Fe and Zn are globally widespread, causing serious health problems such as anaemia, poor pregnancy outcomes, increased risk of morbidity and mortality, stunted growth and impaired physical and cognitive development. Edible insects, of which a diversity of over 2000 species is available, are dietary components for about 2 billion individuals and are a valuable source of animal protein. In the present paper, we review the available information on Fe and Zn in edible insects and their potential as a source of these micronutrients for the rapidly growing human population. The levels of Fe and Zn present in eleven edible insect species that are mass-reared and six species that are collected from nature are similar to or higher than in other animal-based food sources. High protein levels in edible insect species are associated with high Fe and Zn levels. Fe and Zn levels are significantly positively correlated. Biochemically, Fe and Zn in insects occur predominantly in non-haem forms, bound to the proteins ferritin, transferrin and other transport and storage proteins. Knowledge gaps exist for bioavailability in the human alimentary tract, the effect of anti-nutritional factors in other dietary components such as grains on Fe and Zn absorption and the effect of food preparation methods. We conclude that edible insects present unique opportunities for improving the micronutrient status of both resource-poor and Western populations.
Stars are the main ingredients of galaxies, and the sites of the creation of most chemical elements in our universe. The knowledge that we gain from studying nearby resolved stellar populations assists directly our ability to measure the properties of distant galaxies. The overall objective of this project is to study galaxy formation and evolution in a complete environment of the dwarf galaxies in the Local Group, by using the same methods for all of them. For that purpose, we used the INT to conduct a monitoring survey of the majority of Local-Group dwarf galaxies in order to identify the most evolved AGB stars that are long-period variables (LPV). LPV stars reach their maximum brightness amplitudes at optical wavelengths, owing to changes in temperature. They trace stellar populations as young as ∼30 Myr up to as old as ∼10 Gyr, and identifying them is one of the best ways of reconstructing star-formation history using a method that we have developed and applied successfully to other Local-Group galaxies. Since the luminosity variations span 100–1000 days, we planned observations over 10 epochs, spaced ∼3 months apart; 9 epochs of data have so far been obtained.
Supernova (SN) 1987A has provided a unique opportunity to study how SN ejecta evolve in 30 years time scale. We report our ALMA spectral observations of SN 1987A, taken in 2014, 2015 and 2016, with detections of CO, 28SiO, HCO+ and SO, with weaker lines of 29SiO.
We find a dip in the SiO line profiles, suggesting that the ejecta morphology is likely elongated. The difference of the CO and SiO line profiles is consistent with hydrodynamic simulations, which show that Rayleigh-Taylor instabilities causes mixing of gas, with heavier elements much more disturbed, making more elongated structure.
Using 28SiO and its isotopologues, Si isotope ratios were estimated for the first time in SN 1987A. The estimated ratios appear to be consistent with theoretical predictions of inefficient formation of neutron rich atoms at lower metallicity, such as observed in the Large Magellanic Cloud (about half a solar metallicity).
The deduced large HCO+ mass and small SiS mass, which are inconsistent to the predictions of chemical model, might be explained by some mixing of elements immediately after the explosion. The mixing might have made some hydrogen from the envelope to sink into carbon and oxygen-rich zone during early days after the explosion, enabling the formation of a substantial mass of HCO+. Oxygen atoms may penetrate into silicon and sulphur zone, suppressing formation of SiS.
Our ALMA observations open up a new window to investigate chemistry, dynamics and explosive-nucleosynthesis in supernovae.
The spectral energy distributions of 16 AGB stars in the LMC are fitted. The 6 known oxygen-rich stars are well fitted with silicate dust. Due to the completely different absorption properties of silicate and carbonaceous dust we argue that of the 10 stars of unknown spectral type, 1 is probably O-rich while the other 9 are probably C-rich.
The Period-Luminosity relation is discussed. Both the O- and C-rich LPVs in this study appear to lie on extensions of P-L relations derived for stars with much shorter periods.
We used ISOCAM and ISOPHOT to observe the spectral energy distribution between 3.6 and 60 μm of AGB stars in the Small Magellanic Cloud detected by IRAS. CAM-CVF spectra are made which enable us to establish the carbon- or oxygen-rich nature of the stars.
We are in the process of analysing this data using a radiative transfer model. This will provide us with accurate determinations of luminosity and mass loss rate. Combining the results on the SMC, LMC and Galaxy we hope to address the open question of the metallicity dependencies of the mass loss rate. This in turn is important in the ejection of matter by AGB stars into the interstellar medium.
The liquidity premium on corporate bonds has been high on the agenda of Solvency regulators owing to its potential relationship to an additional discount factor on long-dated insurance liabilities. We analyse components of the credit spread as a function of standard bond characteristics during 2003–2014 on a daily basis by regression analyses, after introducing a new liquidity proxy. We derive daily distributions of illiquidity contributions to the credit spread at the individual bond level and find that liquidity premia were close to zero just before the financial crisis. We observe the time-varying nature of liquidity premia as well as a widening in the daily distribution in the years after the credit crunch. We find evidence to support higher liquidity premia, on average, on bonds of lower credit quality. The evolution of model parameters is economically intuitive and brings additional insight into investors’ behaviour. The frequent and bond-level estimation of liquidity premia, combined with few data restrictions makes the approach suitable for ALM modelling, especially when future work is directed towards arriving at forward-looking estimates at both the aggregate and bond-specific level.
In the new DR-A in-situ diffusion experiment at Mont Terri, a perturbation (replacement of the initial synthetic porewater in the borehole with a high-salinity solution) has been induced to study the effects on solute transport and retention, and more importantly, to test the predictive capability of reactive transport codes. Reactive transport modeling is being performed by different teams (IDAEA-CSIC, PSI, Univ. Bern, Univ. British Columbia, Lawrence Berkeley Natl. Lab.). Initial modeling results using the CrunchFlow code and focusing on Cs+ behavior are reported here.
Betelgeuse is one of the most magnificent stars in the sky, and one of the nearest red supergiants. Astronomers gathered in Paris in the Autumn of 2012 to decide what we know about its structure, behaviour, and past and future evolution, and how to place this in the general context of the class of red supergiants. Here I reflect on the discussions and propose a synthesis of the presented evidence. I believe that, in those four days, we have achieved to solve a few riddles.
The Sun is located inside an enormous local cavity filled with a million degree, ionized hydrogen gas and surrounded by a wall of dense and cold gas, this cavity is known as the Local Bubble (LB). Since the tempreture of Local Bubble is high, the typical singly-ionized atoms or molecules can not survive at this high tempreture. To overcome this problem we should probe the Local Bubble using species which survive under this condition so we have done a whole sky survey in north hemisphere by observing absorptions in the Diffuse Interstellar Bands (DIBs) for sight-lines with distance >300 pc. We have done 30 nights observation and have observed 473 bright stars. We found that the correlations between 5780 Å DIBs and Na I D doublets inside of the LB is much more than carriers outside of the LB.
In a quest to further our understanding of the diffuse interstellar medium (ISM) as well as the unidentified carriers of the diffuse interstellar bands (DIBs), we are mapping DIBs across the sky using hundreds of hot stars as background torches – globular clusters (in particular ω Centauri), nearby stars in and around the Local Bubble, and stars within the Magellanic Clouds. I describe the results so far obtained and our current experiments.
The Magellanic System represents one of the best places to study the formation and evolution of galaxies. Photometric surveys of various depths, areas and wavelengths have had a significant impact on our understanding of the system; however, a complete picture is still lacking. VMC (the VISTA near-infrared YJKs survey of the Magellanic System) will provide new data to derive the spatially resolved star formation history and to construct a three-dimensional map of the system. These data combined with those from other ongoing and planned surveys will give us an absolutely unique view of the system opening up the doors to truly new science!
A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40°, spanning longitudes 167° through 360°to 79° at b = 0°, plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg2. The brightness temperature sensitivity will be very good, typically σT≃ 1 K at resolution 30 arcsec and 1 km s−1. The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.