Calculating the Habitable Zone of Multiple Star Systems (http://astro.twam.info/hz)

We have developed a comprehensive methodology and an interactive website for calculating the habitable zone (HZ) of multiple star systems. Using the concept of spectral weight factor, as introduced in our previous studies of the calculations of HZ in and around binary star systems, we calculate the contribution of each star (based on its spectral energy distribution) to the total flux received at the top of the atmosphere of an Earth-like planet, and use the models of the HZ of the Sun to determine the boundaries of the HZ in multiple star systems. Our interactive website for carrying out these calculations is publicly available at http://astro.twam.info/hz . We discuss the details of our methodology and present its application to some of the multiple star systems detected by the Kepler space telescope. We also present the instructions for using our interactive website, and demonstrate its capabilities by calculating the HZ for two interesting analytical solutions of the three-body problem.Comment: 35 pages, 15 figures, accepted for publication in ApJ. Our Multistar Habitable Zone Calculator website is publicly available at http://astro.twam.info/hz . You are welcome to use any of the figures created with this website in your papers, presentations and for teaching. In that case, we ask you that you kindly cite this paper and mention the URL address to the websit

Parallelized Solution Method of the Three-dimensional Gravitational Potential on the Yin-Yang Grid

We present a new method for solving the three-dimensional gravitational potential of a density field on the Yin-Yang grid. Our algorithm is based on a multipole decomposition and completely symmetric with respect to the two Yin-Yang grid patches. It is particularly efficient on distributed-memory machines with a large number of compute tasks, because the amount of data being explicitly communicated is minimized. All operations are performed on the original grid without the need for interpolating data onto an auxiliary spherical mesh.Comment: 8 pages, 4 figures; two minor additions after refereeing; accepted by Ap

Towards a fitting procedure to deeply virtual meson production -- the next-to-leading order case --

Based on the collinear factorization approach, we present a comprehensive perturbative next-to-leading (NLO) analysis of deeply virtual meson production (DVMP). Our representation in conformal Mellin space can serve as basis for a global fitting procedure to access generalized parton distributions from experimental measurements of DVMP and deeply virtual Compton scattering (DVCS). We introduce a rather general formalism for the evaluation of conformal moments that can be developed further beyond the considered order. We also confirm previous diagrammatical findings in the pure singlet quark channel. Finally, we use the analytic properties of the hard scattering amplitudes to estimate qualitatively the size of radiative corrections and illustrate these considerations with some numerical examples. The results suggest that global NLO GPD fits, including both DVMP and DVCS data, could be more stable than often feared.Comment: 125 pages, 7 figures, 8 table

Fostering Macroeconomic Research on Hydrogen-Powered Aviation: A Systematic Literature Review on General Equilibrium Models

Hydrogen is a promising fuel to decarbonize aviation, but macroeconomic studies are currently missing. Computable general equilibrium (CGE) models are suitable to conduct macroeconomic analyses and are frequently employed in hydrogen and aviation research. The main objective of this paper is to investigate existing CGE studies related to (a) hydrogen and (b) aviation to derive a macroeconomic research agenda for hydrogen-powered aviation. Therefore, the well-established method of systematic literature review is conducted. First, we provide an overview of 18 hydrogen-related and 27 aviation-related CGE studies and analyze the literature with respect to appropriate categories. Second, we highlight key insights and identify research gaps for both the hydrogen- and aviation-related CGE literature. Our findings comprise, inter alia, hydrogen’s current lack of cost competitiveness and the macroeconomic relevance of air transportation. Research gaps include, among others, a stronger focus on sustainable hydrogen and a more holistic perspective on the air transportation system. Third, we derive implications for macroeconomic research on hydrogen-powered aviation, including (I) the consideration of existing modeling approaches, (II) the utilization of interdisciplinary data and scenarios, (III) geographical suitability, (IV) the application of diverse policy tools and (V) a holistic perspective. Our work contributes a meaningful foundation for macroeconomic studies on hydrogen-powered aviation. Moreover, we recommend policymakers to address the macroeconomic perspectives of hydrogen use in air transportation