Search

We present an analysis of several Jovian Io-related decametric radio storms recorded in 2004????2012 at the Ukrainian array UTR-2using the new generation of baseband digital receivers. Continuous baseband sampling within sessions lasting for several hoursenabled us to study the evolution of multiscale spectral patterns during the whole storm at varying time and frequency resolutionsand trace the temporal transformation of burst structures in unprecedented detail. In addition to the well-known frequency driftingmillisecond patterns known as S bursts we detected two other classes of events that often look like S bursts at low resolution but reveala more complicated structure in high resolution dynamic spectra. The emissions of the first type (LS bursts, superposition of L andS type emissions) have a much lower frequency drift rate than the usual quasi linearly drifting S bursts (QS) and often occur withina frequency band where L emission is simultaneously present, suggesting that both LS and at least part of L emissions may comefrom the same source. The bursts of the second type (modulated S bursts called MS) are formed by a wideband frequency-modulatedenvelope that can mimic S bursts with very steep negative (or even positive) drift rates. Observed with insu cient time-frequencyresolution, MS look like S bursts with complex shapes and varying drifts; MS patterns often occur in association with (i) narrowbandemission; (ii) S burst trains; or (iii) sequences of fast drift shadow events. We propose a phenomenological description for varioustypes of S emissions, that should include at least three components: high- and low-frequency limitation of the overall frequency bandof the emission, fast frequency modulation of emission structures within this band, and emergence of elementary S burst substructures,that we call “forking” structures. All together, these three components can produce most of the observed spectral structures, includingS bursts with apparently very comple

The field of exoplanetary science is making rapid progress both in statistical studies of exoplanet properties as well as in individual characterization. As space missions provide an emerging picture of formation and evolution of exoplanetary systems, the search for habitable worlds becomes one of the fundamental issues to address. To tackle such a complex challenge, we need to specify the conditions favorable for the origin, development and sustainment of life as we know it. This requires the understanding of global (astrospheric) and local (atmospheric, surface and internal) environments of exoplanets in the framework of the physical processes of the interaction between evolving planet-hosting stars along with exoplanetary evolution over geological timescales, and the resulting impact on climate and habitability of exoplanets. Feedbacks between astrophysical, physico-chemical atmospheric and geological processes can only be understood through interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary, Earth sciences, astrobiology, and the origin of life communities. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets and potential exomoons around them may significantly modify the extent and the location of the habitable zone and provide new directions for searching for signatures of life. Thus, characterization of stellar ionizing outputs becomes an important task for further understanding the extent of habitability in the universe. The goal of this white paper is to identify and describe promising key research goals to aid the theoretical characterization and observational detection of ionizing radiation from quiescent and flaring upper atmospheres of planet hosts as well as properties of stellar coronal mass ejections and stellar energetic particle events., Comment: White Paper submitted to the Astronomy and Astrophysics Decadal Survey (Astro2020), 8 pages, 1 figure

The field of exoplanetary science is making rapid progress both in statistical studies of exoplanet properties as well as in individual characterization. As space missions provide an emerging picture of formation and evolution of exoplanetary systems, the search for habitable worlds becomes one of the fundamental issues to address. To tackle such a complex challenge, we need to specify the conditions favorable for the origin, development and sustainment of life as we know it. This requires the understanding of global (astrospheric) and local (atmospheric, surface and internal) environments of exoplanets in the framework of the physical processes of the interaction between evolving planet-hosting stars along with exoplanetary evolution over geological timescales, and the resulting impact on climate and habitability of exoplanets. Feedbacks between astrophysical, physico-chemical atmospheric and geological processes can only be understood through interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary, Earth sciences, astrobiology, and the origin of life communities. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets and potential exomoons around them may significantly modify the extent and the location of the habitable zone and provide new directions for searching for signatures of life. Thus, characterization of stellar ionizing outputs becomes an important task for further understanding the extent of habitability in the universe. The goal of this white paper is to identify and describe promising key research goals to aid the theoretical characterization and observational detection of ionizing radiation from quiescent and flaring upper atmospheres of planet hosts as well as properties of stellar coronal mass ejections and stellar energetic particle events., Comment: White Paper submitted to the Astronomy and Astrophysics Decadal Survey (Astro2020), 8 pages, 1 figure

On August 18, 1999, the Cassini spacecraft flew by Earth at an altitude of 1186 km on its way to Saturn. Although the flyby was performed exclusively to provide the spacecraft with sufficient velocity to get to Saturn, the radio and plasma wave science (R