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The prospects for the habitability of M-dwarf planets have long been debated, due to key differences between the unique stellar and planetary environments around these low-mass stars, as compared to hotter, more luminous Sun-like stars.…
We consider global catastrophic risks due to cosmic explosions (supernovae, magnetars and gamma-ray bursts) and possible mitigation strategies by humans and other hypothetical intelligent beings. While by their very nature these events are…
To develop a spacefaring civilization, humankind must develop technologies which enable safe, affordable and repeatable mobility through the solar system. One such technology is nuclear fusion propulsion which is at present under study…
Stellar activity and rotation frustrate the detection of exoplanets through the radial velocity technique. This effect is particularly of concern for M dwarfs, which can remain magnetically active for billions of years. We compile rotation…
Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can…
To deflect impact-trajectory of massive km^3 and spinning asteroid by a few terrestrial radius one need a large momentum exchange. The dragging of huge spinning bodies in space by external engine seems difficult or impossible. Our solution…
The measurement of chemical abundances in planetary nebulae in nearby galaxies is now relatively straightforward. The challenge is to use these chemical abundances to infer the chemical evolution of their host galaxies. At this point, our…
The outflows of asymptotic giant branch (AGB) stars are rich astrochemical laboratories, hosting different chemical regimes: from non-equilibrium chemistry close to the star, to dust formation further out, and finally photochemistry in the…
The detection of exoplanets orbiting other stars has revolutionized our view of the cosmos. First results suggest that it is teeming with a fascinating diversity of rocky planets, including those in the habitable zone. Even our closest…
Rocky planets orbiting M-dwarf stars are prime targets for atmospheric characterization, yet their long-term evolution under intense stellar winds and high-energy radiation remains poorly constrained. The Kepler-1649 system, hosting two…
Habitable rocky planets around M dwarfs that have H2-dominated atmospheres, if they exist, would permit characterizing habitable exoplanets with detailed spectroscopy using JWST, owing to their extended atmospheres and small stars. However,…
Many planets are observed in stellar binary systems, and their frequency may be comparable to that of planetary systems around single stars. Binary stellar evolution in such systems influences the dynamical evolution of the resident…
The recent detection of Earth-sized planets in the habitable zone of Proxima Centauri, Trappist-1 and many other nearby M-type stars has led to speculations, whether liquid water and life actually exist on these planets. To a large extent,…
In recent years a paradigm shift has occurred in exoplanet science, wherein low-mass stars are increasingly viewed as a foundational pillar of the search for potentially habitable worlds in the solar neighborhood. However, the formation…
We study how migration affects stars of a galaxy with a thin stellar disc and thicker stellar components. The simulated galaxy has a strong bar and lasting spiral arms. We find that the amplitude of the churning (change in angular momentum)…
Extragalactic jets are launched from the innermost regions of galaxies, near the central supermassive black hole. As they propagate, they must cross the whole galaxy, and in this process they interact with a variety of obstacles; including…
Secular perturbations from binary stars and distant massive planets can drive cold planets onto nearly parabolic orbits with pericenter passages extremely close to their host stars. Meanwhile, short-period super-Earths are frequently…
Contrary to popular belief, the interstellar medium (ISM) is not empty; it is filled with atoms, dust particles, and molecules. Some of these molecules may have been the very building blocks of life that, delivered to Earth via comets and…
K2-18b closely orbits a nearby M3 dwarf within its habitable zone, where this planet could be either a super-Earth or a mini-Neptune. Recent studies using transit spectroscopy suggest that it is Hycean in nature, but this classification is…
In the nearly 60 years of spaceflight we have accomplished wonderful feats of exploration that have shown the incredible spirit of the human drive to explore and understand our universe. Yet in those 60 years we have barely left our solar…