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In questo breve incontro, Caterina Boccato nelle veci del responsabile nazionale della didattica e divulgazione, Stefano Sandrelli, presenta la Struttura per la Comunicazione della Presidenza con particolare riguardo alla didattica e alla divulgazione (D&D).
Il seminario sara` un’importante occasione di incontro per illustrare ai ricercatori INAF in che modo questa struttura può essere loro utile e che cosa la struttura si aspetta da parte dei ricercatori. A tal fine ne racconterà la strategia e gli strumenti adottati con una panoramica di quanto è stato fatto nel 2017 e nel 2018, mettendo in evidenza aspetti, efficaci e non, delle attività svolte. Per finire, uno sguardo al programma futuro.

The study of the interaction of cosmic rays with the interstellar matter is a multi-disciplinary investigation that involves the analysis of several physical and chemical processes: ionisation of atomic and molecular hydrogen, energy loss by elastic and inelastic collisions, energy deposition by primary and secondary electrons, gamma-ray production by pion decay, the production of light elements by spallation reactions, and much more. Cosmic-ray ionisation activates the rich chemistry of dense molecular clouds and determines the degree of coupling of the gas with the local magnetic field, which in turn controls the collapse timescale and the star-formation efficiency of a molecular cloud. In recent years a wealth of observations from the ground and from space has provided information and constraints that still need to be incorporated in a consistent global theoretical framework. My goal is to use the results of chemical models and state-of-the-art numerical simulations supplemented by dedicated observations to provide a unifying interpretation of the data with a model of cosmic-ray propagation specifically developed to make predictions that can be tested against the observations. Finally, I will talk about my most recent study: a mechanism able to accelerate local thermal particles in protostars that can be used to explain the high ionisation rate as well as the synchrotron emission observed towards protostellar sources.

The accurate and timely prediction of solar eruptions is important for many space weather prediction tools and the Solar Orbiter mission. The aim of this study is to propose a new technique for the automated prediction of magnetic flux rope ejections in data driven NLFFF simulations hours in advance. We use a data-driven NLFFF model to describe the evolution of the 3D magnetic field of 8 active regions: 5 that produced an eruption and 3 where no eruption was observed. From the 3D magnetic field configuration, we determine a possible proxy for the loss of equilibrium of the magnetic flux rope based on the Lorentz force. Such proxy is significantly higher for the simulations of the eruptive active regions. For some cases, using a subset of the observed magnetograms, we ran a series of predictive simulations to test whether the time evolution of the proxy project forward in time can be used to predict the eruptions. We find that the identified proxy is useful in anticipating the magnetic flux rope ejection and that a meaningful prediction can be made up to 10 hours in advance. Although a number of issues need to be addressed for a fully operational application, this study presents an interesting solution for the prediction of CME onsets and future studies will address how to generalise the model such that it can be used.

The interaction of the shock waves originated from supernova explosions with the circumstellar medium provides crucial information on the physics of shock heating. Astrophysical shocks at all scales, from those in the heliosphere up to the cosmological shock waves, are typically collisionless and electrons, protons, and ions are expected to be heated at different temperatures. Although optical observations of Balmer-dominated shocks in young SNRs showed that the post-shock proton temperature is higher than the electron temperature, the actual dependence of the post-shock temperature on the particle mass is still widely debated. We tackle this longstanding issue through the analysis of deep multi-epoch and high-resolution observations of SN 1987A, made with the Chandra X-ray telescope. We study the observed spectra in close comparison with a dedicated full 3-D hydrodynamic simulation. The simulation is able to reproduce self-consistently the whole broadening of the spectral lines of many ions altogether. We could therefore measure the post shock temperature of protons and selected ions in the shocked circumstellar medium. We found that the ion to proton temperature ratio is always significantly higher than one and increases linearly with the ion mass for a wide range of masses and shock parameters. This provides information about the heating processes in collisionless shocks.

Very Hot Super-Earths with an Atmosphere: A Model Explaining Their Paradoxical Existence

The aim of this research is to constrain the interior structures and evolutions of hot super-Earths, particularly that of 55 Cancri e. Herewith, we propose an alternative model for the paradoxical nature of small, hot super-Earths with atmospheres. Our model does not require these bodies to contain large quantities of ices in order to account for their low densities, which has been a subject of dispute considering their high surface temperatures and the potentially strong internal heat processes such as tidal flexing or radiogenic heating. The first aspect of our research involved calculating the total H₂ reservoir in 55 Cancri e which is ~ 2×10²³ kg (0.04 M_⨁). We then encountered a theoretical enigma since the UV and X-Ray induced mass loss should have been strong enough to evaporate the atmosphere billions of years ago, which is inconsistent with astronomical data showing a currently plentiful atmosphere. This issue can be completely avoided by showing that for a tidally locked setup, the mass loss rates on the night-side are negligible thus allowing the planet to maintain a H₂-rich atmosphere above half its surface. In the case of 55 Cancri e, it became tidally locked approximately 50 ± 250 Myrs after it formed implying that from that moment onwards the radius and mass of the body changed negligibly. Prior to this time mass loss rates were very strong and approximately homogeneous which when modelled, showed that 55 Cancri e was born as a Neptunian-or-Jovian-type exoplanet. Finally, we propose that the bimodal distribution in exoplanet radii may be the result of two different evolutionary paths; one where a super-Earth loses all of its atmosphere before it becomes tidally locked (resulting in the peak at ~ 1.3 R_⨁), and the other when super-Earths become tidally locked before losing their atmosphere allowing them to maintain it (resulting in the other peak at ~ 2.4 R_⨁).

The cosmic ray (CR) spectrum detected at Earth is a non-trivial combination of the spectrum released by the sources and of the CR propagation and interaction with the interstellar medium (ISM). CRs in the ISM are scattered by the turbulent magnetic field, and, depending on their energy and species, they can incur in severe energy losses. In addition, CRs  can  themselves  excite  magnetic  turbulence  in  the background plasma and generate large scale flows like galactic winds, thus affecting  their own  transport.
In this talk I will discuss some  implications of the CR-ISM interaction, in particular  the formation of galactic winds,  the CR escape and propagation in the source proximity, the identification of the sources of TeV CR electrons and  the ionization of molecular clouds.

prova