The new CYCOFOS forecasting at coastal, sub-regional and regional scales in the Mediterranean and the Black Sea

<p>The Cyprus coastal ocean forecasting system, known as CYCOFOS has been providing operational hydrodynamical and sea state forecasts in the Eastern Mediterranean since early 2002. Recently, it has been improved with the implementation of new hydrodynamic and new wave modeling systems with the objective of targeting higher resolution domains, at coastal, sub-regional and regional scales in the Mediterranean and the Black Sea. For the new CYCOFOS hydrodynamic modeling system a novel parallel version of the well established POM has been implemented. The new CYCOFOS hydrodynamical models covers the entire Eastern Mediterranean with a resolution of 2 km and the Levantine Basin with a resolution of ~600 m, both nested in the Copernicus Marine Environmental Monitoring Service of the Mediterranean Forecasting Center-CMEMS Med MFC. For sea waves forecasting, CYCOFOS has implemented  the new ECMWF wave model WAM CY46R1 in the Mediterranean and the Black seas at a higher resolution of 5 km. The CYCOFOS hydrodynamical models received an extended cal/val against the parent model, Argo profiles and satellite SST time series, while in-situ wave data gathered by the HERMES buoy monitoring network in the Eastern Mediterranean and the Black Sea were used for statistical validation of the new CYCOFOS wave forecasts. The new CYCOFOS validated modeling systems,  provide higher resolution quality controlled forecasting data suiting the needs for : a) down-streaming applications supporting risk assessment for offshore platforms in the Levantine Basin and studies concerning the coastal erosion in the Eastern Mediterranean (Albania, Cyprus, Greece) and the Black Sea (Bulgaria) in the framework of the HERMES project, and b) further hierarchical downscaling applications for the development of the COASTAL CRETE operation forecasting system at a higher resolution in the Eastern Mediterranean (Crete, Greece).</p>

Progenitor properties of type II supernovae: fitting to hydrodynamical models using Markov chain Monte Carlo methods

Context. The progenitor and explosion properties of type II supernovae (SNe II) are fundamental to understanding the evolution of massive stars. Particular attention has been paid to the initial masses of their progenitors, but despite the efforts made, the range of initial masses is still uncertain. Direct imaging of progenitors in pre-explosion archival images suggests an upper initial mass cutoff of ∼18 M⊙. However, this is in tension with previous studies in which progenitor masses inferred by light-curve modelling tend to favour high-mass solutions. Moreover, it has been argued that light-curve modelling alone cannot provide a unique solution for the progenitor and explosion properties of SNe II. Aims. We develop a robust method which helps us to constrain the physical parameters of SNe II by simultaneously fitting their bolometric light curve and the evolution of the photospheric velocity to hydrodynamical models using statistical inference techniques. Methods. We created pre-supernova red supergiant models using the stellar evolution code MESA, varying the initial progenitor mass. We then processed the explosion of these progenitors through hydrodynamical simulations, where we changed the explosion energy and the synthesised nickel mass together with its spatial distribution within the ejecta. We compared the results to observations using Markov chain Monte Carlo methods. Results. We apply this method to a well-studied set of SNe with an observed progenitor in pre-explosion images and compare with results in the literature. Progenitor mass constraints are found to be consistent between our results and those derived by pre-SN imaging and the analysis of late-time spectral modelling. Conclusions. We have developed a robust method to infer progenitor and explosion properties of SN II progenitors which is consistent with other methods in the literature. Our results show that hydrodynamical modelling can be used to accurately constrain the physical properties of SNe II. This study is the starting point for a further analysis of a large sample of hydrogen-rich SNe.

A Modelling System for Power Consumption of Marine Traffic

The International Maritime Organization (IMO) has enforced stricter limit on the Greenhouse Gas (GHG) emission due to environment and climate concern. The measures to reduce GHG emissions from shipping can be divided into two groups. The first one is to improve ship energy efficiency through new technology, optimized operation and logistics, and the second one is to introduce alternative fuels with lower carbon intensity. However, the effectiveness and applicability of any measure depend on ship type, ship size, operation type, operation environment (wind and wave condition), as well as the cost of the measure. It is necessary to evaluate new measures in real shipping scenario. Modeling of ship fuel consumption and emission are fundamental input to evaluate the impacts of shipping on the environment and climate, and to evaluate new measures for reducing GHG emission. A modeling system is developed to estimate ship fuel consumption and emission, based on ship hydrodynamical models, information from Automatic Identification System (AIS), the IHS Fairplay database and metocean data. The modeling system aims to cover most of the ship types equipped with AIS transponders, and it will provide different hydrodynamical models to calculate fuel consumption based on the available ship information. In the paper, the modeling system will be described, and the power consumption from the modeling system are compared with the measurement data on one container ship. The comparison shows that the power consumption predicted with the modeling system agrees with measurement data well. The effects of weather data and measured speed on predicted power consumption are also analyzed.

Ongoing flyby in the young multiple system UX Tauri

We present observations of the young multiple system UX Tauri to look for circumstellar disks and for signs of dynamical interactions. We obtained SPHERE/IRDIS deep differential polarization images in the J and H bands. We also used ALMA archival CO data. Large extended spirals are well detected in scattered light coming out of the disk of UX Tau A. The southern spiral forms a bridge between UX Tau A and C. These spirals, including the bridge connecting the two stars, all have a CO (3–2) counterpart seen by ALMA. The disk of UX Tau C is detected in scattered light. It is much smaller than the disk of UX Tau A and has a major axis along a different position angle, suggesting a misalignment. We performed PHANTOM SPH hydrodynamical models to interpret the data. The scattered light spirals, CO emission spirals and velocity patterns of the rotating disks, and the compactness of the disk of UX Tau C all point to a scenario in which UX Tau A has been perturbed very recently (∼1000 years) by the close passage of UX Tau C.

MHD-shock structures of astrospheres: λ Cephei -like astrospheres

ABSTRACT The interpretation of recent observations of bow shocks around O-stars and the creation of corresponding models require a detailed understanding of the associated (magneto-)hydrodynamic structures. We base our study on 3D numerical (magneto-)hydrodynamical models, which are analysed using the dynamically relevant parameters, in particular, the (magneto)sonic Mach numbers. The analytic Rankine–Hugoniot relation for HD and MHD are compared with those obtained by the numerical model. In that context, we also show that the only distance which can be approximately determined is that of the termination shock, if it is an HD shock. For MHD shocks, the stagnation point does not, in general, lie on the inflow line, which is the line parallel to the inflow vector and passing through the star. Thus an estimate via the Bernoulli equation as in the HD case is, in general, not possible. We also show that in O-star astrospheres, distinct regions exist in which the fast, slow, Alfvénic, and sonic Mach numbers become lower than one, implying subslow magnetosonic as well as subfast and subsonic flows. Nevertheless, the analytic MHD Rankine–Hugoniot relations can be used for further studies of turbulence and cosmic ray modulation.

Radiation-hydrodynamical models of X-ray photoevaporation in carbon-depleted circumstellar discs

ABSTRACT The so-called transition discs provide an important tool to probe various mechanisms that might influence the evolution of protoplanetary discs and therefore the formation of planetary systems. One of these mechanisms is photoevaporation due to energetic radiation from the central star, which can in principal explain the occurrence of discs with inner cavities like transition discs. Current models, however, fail to reproduce a subset of the observed transition discs, namely objects with large measured cavities and vigorous accretion. For these objects the presence of (multiple) giant planets is often invoked to explain the observations. In our work, we explore the possibility of X-ray photoevaporation operating in discs with different gas-phase depletion of carbon and show that the influence of photoevaporation can be extended in such low-metallicity discs. As carbon is one of the main contributors to the X-ray opacity, its depletion leads to larger penetration depths of X-rays in the disc and results in higher gas temperatures and stronger photoevaporative winds. We present radiation-hydrodynamical models of discs irradiated by internal X-ray + EUV radiation assuming carbon gas-phase depletions by factors of three, 10, and 100 and derive realistic mass-loss rates and profiles. Our analysis yields robust temperature prescriptions as well as photoevaporative mass-loss rates and profiles which may be able to explain a larger fraction of the observed diversity of transition discs.

Measurements of Anisotropic Flow in Xe–Xe Collisions at √sNN = 5.44 TeV Using the ALICE Detector

These proceedings summarise the first measurements of anisotropic flow coefficients v n , 2 ≤ n ≤ 4 , for inclusive charged particles at mid-rapidity in Xe–Xe collisions at s NN = 5 . 44 TeV . The results are compared with those from Pb–Pb collisions at s NN = 5 . 02 TeV , in order to test the initial state (IS) models and transport properties. The resulting differences in v 2 and v 3 between the two systems are consistent with two different hydrodynamical models. Moreover, it is expected that the ratios between v n and their corresponding eccentricities for n = 2 , 3 scale with transverse density. This is observed for some IS models, except for some deviations in central collisions. These results assist in constraining the initial state as well as the hydrodynamical propagation of the system.

Analysis of surface effect on solar-like oscillation frequencies using 3D hydrodynamical models

We evaluate the frequency difference between standard stellar models and models patched with 3D hydrodynamical models across the Teff–g plane. It allows us to constrain frequency corrections for surface effect. The coefficients in the correction functionals are thus provided as functions of effective temperature and surface gravity.