Hints about the multiplicity of WR 133 based on multiepoch radio observations

Several tens of massive binary systems display indirect, or even strong evidence for non-thermal radio emission, hence their particle accelerator status. These objects are referred to as particle-accelerating colliding-wind binaries (PACWBs). WR 133 is one of the shortest period Wolf-Rayet + O systems in this category, and is therefore critical to characterize the boundaries of the parameter space adequate for particle acceleration in massive binaries. Our methodology consists in analyzing JVLA observations of WR 133 at different epochs to search for compelling evidence for a phase-locked variation attributable to synchrotron emission produced in the colliding-wind region. New data obtained during two orbits reveal a steady and thermal emission spectrum, in apparent contradiction with the previous detection of non-thermal emission. The thermal nature of the radio spectrum along the 112.4-d orbit is supported by the strong free–free absorption by the dense stellar winds, and shows that the simple binary scenario cannot explain the non-thermal emission reported previously. Alternatively, a triple system scenario with a wide, outer orbit would fit with the observational facts reported previously and in this paper, albeit no hint for the existence of a third component exists to date. The epoch-dependent nature of the identification of synchrotron radio emission in WR 133 emphasizes the issue of observational biases in the identification of PACWBs, that undoubtedly affect the present census of PACWB among colliding-wind binaries.

Stratospheric isotopic water profiles from a single submillimeter limb scan by TELIS

Around 490 GHz relatively strong HDO and H218O emission lines can be found in the submillimeter thermal-emission spectrum of the Earth's atmosphere, along with lines of the principal isotopologue of water vapour. These can be used for remote sensing of the rare/principal isotope ratio in the stratosphere. A sensitivity study has been performed for retrieval simulations of water isotopologues from balloon-borne measurements by the limb sounder TELIS (TErahertz and submillimeter LImb Sounder). The study demonstrates the capability of TELIS to determine, from a single limb scan, the profiles for H218O and HDO between 20 km and 37 km with a retrieval error of ≈3 and a spatial resolution of 1.5 km, as determined by the width of the averaging kernel. In addition HDO can be retrieved in the range of 10–20 km, albeit with a strongly deteriorated retrieval error. Expected uncertainties in instrumental parameters have only limited impact on the retrieval results.

Stratospheric isotopic water profiles from a single submillimeter limb scan by TELIS

Around 490 GHz relatively strong HDO and H218O emission lines can be found in the submillimeter thermal-emission spectrum of the Earth's atmosphere, along with lines of the principal isotopologue of water vapour. These can be used for remote sensing of the rare/principal isotope ratio in the stratosphere. A sensitivity study has been performed for retrieval simulations of water isotopologues from balloon-borne measurements by the limb sounder TELIS (TErahertz and submillimeter LImb Sounder). The study demonstrates the capability of TELIS to determine, from a single limb scan, the profiles for H218O and HDO between 20 km and 37 km with a retrieval error of ≈3% and a spatial resolution of 1.5 km, as determined by the width of the averaging kernel. In addition HDO can be retrieved in the range of 10–20 km as well, albeit with a strongly deteriorated retrieval error. Expected uncertainties in instrumental parameters have only limited impact on the retrieval results.

Thermal Radiative Heat Transfer Between Closely Spaced Nanostructures

Thermal emission control with nanostructures has attracted considerable attention because of its potential applications in thermophotovoltaic (TPV) devices [1–3]. The optical-to-electrical conversion in a TPV system is driven by photons with energy higher than the electronic bandgap of the photovoltaic cell. A narrow-band emitter with emission spectrum slightly above the bandgap is ideal, which maximizes the conversion efficiency as well as minimizes the waste heat that deteriorates the performance of the cell. Specially designed nanostructures alters the band structure of photons in much the same way as the crystal lattice does on electrons inside semiconductors, thus changing the thermal emission spectrum. By employing nanostructure-enabled emission control, Lin, et al, projected an efficiency of 34% for TPV systems [2].