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Lynch, B.J.; Wood, B.E.; Jin, M.; Török, T.; Sun, X.; Palmerio, E.; ... ; Salman, T.M. 2022

Connecting solar and stellar flares/CMEs: expanding heliophysics to encompass exoplanetary space weather

Research paper

open access

Jong, T. A. de; Benschop, T.; Chen, X.; Krasovskii, E.E.; Dood, M.J.A. de; Tromp, R.M.; ... ; Molen, S.J. van der 2021

Imaging moiré deformation and dynamics in twisted bilayer graphene

Research paper

open access

In twisted bilayer graphene (TBG) a moiré pattern forms that introduces a new length scale to the material. At the 'magic' twist angle of 1.1°, this causes a flat band to form, yielding emergent... Show moreIn twisted bilayer graphene (TBG) a moiré pattern forms that introduces a new length scale to the material. At the 'magic' twist angle of 1.1°, this causes a flat band to form, yielding emergent properties such as correlated insulator behavior and superconductivity [1-4]. In general, the moiré structure in TBG varies spatially, influencing the local electronic properties [5-9] and hence the outcome of macroscopic charge transport experiments. In particular, to understand the wide variety observed in the phase diagrams and critical temperatures, a more detailed understanding of the local moiré variation is needed [10]. Here, we study spatial and temporal variations of the moiré pattern in TBG using aberration-corrected Low Energy Electron Microscopy (AC-LEEM) [11,12]. The spatial variation we find is lower than reported previously. At 500°C, we observe thermal fluctuations of the moiré lattice, corresponding to collective atomic displacements of less than 70pm on a time scale of seconds [13], homogenizing the sample. Despite previous concerns, no untwisting of the layers is found, even at temperatures as high as 600°C [14,15]. From these observations, we conclude that thermal annealing can be used to decrease the local disorder in TBG samples. Finally, we report the existence of individual edge dislocations in the atomic and moiré lattice. These topological defects break translation symmetry and are anticipated to exhibit unique local electronic properties. Show less

Girard, J.H.; Boer, J. de; Haffert, S.Y.; Zeidler, P.; Bohn, A.J.; Holstein, R.G. van; ... ; Bae, J. 2020

Original use of MUSE's laser tomography adaptive optics to directly image young accreting exoplanets

Article in monograph or in proceedings

open access

Leeuwen, C. van; Podareanu, D.; Codreanu, V.; Cai, M.X.; Berg, A.; Portegies Zwart, S.F.; ... ; Bonvin, A.M.J.J. 2020

Deep-learning enhancement of large scale numerical simulations

Research paper

open access

Snellen, I.A.G.; Albrecht, S.; Anglada-Escude, G.; Baraffe, I.; Baudoz, P.; Benz, W.; ... ; Visser, P. de 2019

ESA Voyage 2050 White Paper: Detecting life outside our solar system with a large high-contrast-imaging mission

Research paper

open access

In this white paper, we recommend the European Space Agency plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as... Show moreIn this white paper, we recommend the European Space Agency plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently under study by NASA. Such a mission will be needed to characterize a sizable sample of temperate Earth-like planets in the habitable zones of nearby Sun-like stars and to search for extraterrestrial biological activity. We provide an overview of relevant European expertise, and advocate ESA to start a technology development program towards detecting life outside the Solar system. Show less

Simionescu, A.; Ettori, S.; Werner, N.; Nagai, D.; Vazza, F.; Akamatsu, H.; ... ; Werk, J. 2019

Voyage through the Hidden Physics of the Cosmic Web

Research paper

open access

Nicastro, F.; Kaastra, J.S.; Argiroffi, C.; Behar, E.; Bianchi, S.; Bocchino, F.; ... ; Zappacosta, L. 2019

The Voyage of Metals in the Universe from Cosmological to Planetary Scales: the need for a Very High-Resolution, High Throughput Soft X-ray Spectrometer

Research paper

open access

Metals form an essential part of the Universe at all scales. Without metals we would not exist, and the Cosmos would look completely different. Metals are primarily born through nuclear processes...

Metals form an essential part of the Universe at all scales. Without metals we would not exist, and the Cosmos would look completely different. Metals are primarily born through nuclear processes in stars. They leave their cradles through winds or explosions, and then start their journey through space. This can lead them in and out of astronomical objects on all scales, ranging from comets, planets, stars, entire galaxies, groups and clusters of galaxies to the largest structures of the Universe. Their wanderings are fundamental in determining how these objects, and the entire universe, evolve. In addition, their bare presence can be used to trace what these structures look like. The scope of this paper is to highlight the most important open astrophysical problems that will be central in the next decades and for which a deep understanding of the Universe-wandering metals, their physical and kinematical states and their chemical composition represents the only viable solution. The majority of these studies can only be efficiently performed through High Resolution Spectroscopy in the soft X-ray band.

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Quanz, S.P.; Absil, O.; Angerhausen, D.; Benz, W.; Bonfils, X.; Berger, J.-P.; ... ; Wyatt, M. 2019

Atmospheric characterization of terrestrial exoplanets in the mid-infrared: biosignatures, habitability & diversity

Research paper

open access

Exoplanet science is one of the most thriving fields of modern astrophysics. A major goal is the atmospheric characterization of dozens of small, terrestrial exoplanets in order to search for... Show moreExoplanet science is one of the most thriving fields of modern astrophysics. A major goal is the atmospheric characterization of dozens of small, terrestrial exoplanets in order to search for signatures in their atmospheres that indicate biological activity, assess their ability to provide conditions for life as we know it, and investigate their expected atmospheric diversity. None of the currently adopted projects or missions, from ground or in space, can address these goals. In this White Paper we argue that a large space-based mission designed to detect and investigate thermal emission spectra of terrestrial exoplanets in the MIR wavelength range provides unique scientific potential to address these goals and surpasses the capabilities of other approaches. While NASA might be focusing on large missions that aim to detect terrestrial planets in reflected light, ESA has the opportunity to take leadership and spearhead the development of a large MIR exoplanet mission within the scope of the "Voyage 2050" long-term plan establishing Europe at the forefront of exoplanet science for decades to come. Given the ambitious science goals of such a mission, additional international partners might be interested in participating and contributing to a roadmap that, in the long run, leads to a successful implementation. A new, dedicated development program funded by ESA to help reduce development and implementation cost and further push some of the required key technologies would be a first important step in this direction. Ultimately, a large MIR exoplanet imaging mission will be needed to help answer one of mankind's most fundamental questions: "How unique is our Earth?" Show less

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