A grid of upper atmosphere models for 1--40 MEARTH planets: application to CoRoT-7 b and HD219134 b,c

There is growing observational and theoretical evidence suggesting that atmospheric escape is a key driver of planetary evolution. Commonly, planetary evolution models employ simple analytic formulae (e.g., energy limited escape) that are often inaccurate, and more detailed physical models of atmospheric loss usually only give snapshots of an atmosphere's structure and are difficult to use for evolutionary studies. To overcome this problem, we upgrade and employ an already existing upper atmosphere hydrodynamic code to produce a large grid of about 7000 models covering planets with masses 1 - 39 Earth mass with hydrogen-dominated atmospheres and orbiting late-type stars. The modeled planets have equilibrium temperatures ranging between 300 and 2000 K. For each considered stellar mass, we account for three different values of the high-energy stellar flux (i.e., low, moderate, and high activity). For each computed model, we derive the atmospheric temperature, number density, bulk velocity, X-ray and EUV (XUV) volume heating rates, and abundance of the considered species as a function of distance from the planetary center. From these quantities, we estimate the positions of the maximum dissociation and ionisation, the mass-loss rate, and the effective radius of the XUV absorption. We show that our results are in good agreement with previously published studies employing similar codes. We further present an interpolation routine capable to extract the modelling output parameters for any planet lying within the grid boundaries. We use the grid to identify the connection between the system parameters and the resulting atmospheric properties. We finally apply the grid and the interpolation routine to estimate atmospheric evolutionary tracks for the close-in, high-density planets CoRoT-7 b and HD219134 b,c...Comment: 21 pages, 4 Tables, 15 Figure

The semiclassical limit of quantum gravity and the problem of time

The question about the appearance of time in the semiclassical limit of quantum gravity continues to be discussed in the literature. It is believed that a temporal Schrodinger equation for matter fields on the background of a classical gravitational field must be true. To obtain this equation, the Born - Oppenheimer approximation for gravity is used. However, the origin of time in this equation is different in works of various authors. For example, in the papers of Kiefer and his collaborators, time is a parameter along a classical trajectory of gravitational field; in the works of Montani and his collaborators the origin of time is introducing the Kuchar - Torre reference fluid; in the extended phase space approach the origin of time is the consequence of existing of the observer in a fixed reference frame. We discuss and compare these approaches. To make the calculations transparent, we illustrate them with a model of a closed isotropic universe. In each approach, one obtains some Schrodinger equation for matter fields with quantum gravitational corrections, but the form of the equation and the corrections depend on additional assumptions which are rather arbitrary. None of the approaches can explain how time had appeared in the Early Universe, since it is supposed that classical gravity and, therefore, classical spacetime had already come into being.Comment: 18 pages, no figure, to be published in Int. J. Mod. Phys.

Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters

We investigate the interaction between the magnetized stellar wind plasma and the partially ionized hydrodynamic hydrogen outflow from the escaping upper atmosphere of non- or weakly magnetized hot Jupiters. We use the well-studied hot Jupiter HD 209458b as an example for similar exoplanets, assuming a negligible intrinsic magnetic moment. For this planet, the stellar wind plasma interaction forms an obstacle in the planet's upper atmosphere, in which the position of the magnetopause is determined by the condition of pressure balance between the stellar wind and the expanded atmosphere, heated by the stellar extreme ultraviolet (EUV) radiation. We show that the neutral atmospheric atoms penetrate into the region dominated by the stellar wind, where they are ionized by photo-ionization and charge exchange, and then mixed with the stellar wind flow. Using a 3D magnetohydrodynamic (MHD) model, we show that an induced magnetic field forms in front of the planetary obstacle, which appears to be much stronger compared to those produced by the solar wind interaction with Venus and Mars. Depending on the stellar wind parameters, because of the induced magnetic field, the planetary obstacle can move up to ~0.5-1 planetary radii closer to the planet. Finally, we discuss how estimations of the intrinsic magnetic moment of hot Jupiters can be inferred by coupling hydrodynamic upper planetary atmosphere and MHD stellar wind interaction models together with UV observations. In particular, we find that HD 209458b should likely have an intrinsic magnetic moment of 10-20% that of Jupiter.Comment: 8 pages, 6 figures, 2 tables, accepted to MNRA

The Kepler-11 system: evolution of the stellar high-energy emission and {initial planetary} atmospheric mass fractions

The atmospheres of close-in planets are strongly influenced by mass loss driven by the high-energy (X-ray and extreme ultraviolet, EUV) irradiation of the host star, particularly during the early stages of evolution. We recently developed a framework to exploit this connection and enable us to recover the past evolution of the stellar high-energy emission from the present-day properties of its planets, if the latter retains some remnants of their primordial hydrogen-dominated atmospheres. Furthermore, the framework can also provide constraints on planetary initial atmospheric mass fractions. The constraints on the output parameters improve when more planets can be simultaneously analysed. This makes the Kepler-11 system, which hosts six planets with bulk densities between 0.66 and 2.45g cm^{-3}, an ideal target. Our results indicate that the star has likely evolved as a slow rotator (slower than 85\% of the stars with similar masses), corresponding to a high-energy emission at 150 Myr of between 1-10 times that of the current Sun. We also constrain the initial atmospheric mass fractions for the planets, obtaining a lower limit of 4.1% for planet c, a range of 3.7-5.3% for planet d, a range of 11.1-14% for planet e, a range of 1-15.6% for planet f, and a range of 4.7-8.7% for planet g assuming a disc dispersal time of 1 Myr. For planet b, the range remains poorly constrained. Our framework also suggests slightly higher masses for planets b, c, and f than have been suggested based on transit timing variation measurements. We coupled our results with published planet atmosphere accretion models to obtain a temperature (at 0.25 AU, the location of planet f) and dispersal time of the protoplanetary disc of 550 K and 1 Myr, although these results may be affected by inconsistencies in the adopted system parameters.Comment: 8 pages, 3 figure

Modeling the Lyα\alpha transit absorption of the hot Jupiter HD 189733b

Hydrogen-dominated atmospheres of hot exoplanets expand and escape due to the intense heating by the X-ray and extreme ultraviolet (XUV) irradiation of their host stars. Excess absorption of neutral hydrogen has been observed in the Ly$\alpha$ line during transits of several close-in exoplanets, indicating such extended atmospheres. For the hot Jupiter HD 189733b, this absorption shows temporal variability. Variations in stellar XUV emission and/or stellar wind conditions have been invoked to explain this effect. We apply a 1D hydrodynamic upper atmosphere model and a 3D MHD stellar wind flow model to study the effect of variations of the stellar XUV and wind conditions on the neutral hydrogen distribution, including the production of energetic neutral atoms (ENAs), and the related Ly$\alpha$ transit signature. We obtain comparable, albeit slightly higher Ly$\alpha$ absorption as observed in 2011 with a stellar XUV flux of $1.8\times10^4$ erg cm$^{-2}$ s$^{-1}$, rather typical activity conditions for this star. Flares similar to the one observed 8 h before the transit are unlikely to have caused a significant modulation of the transit signature. The resulting Ly$\alpha$ absorption is dominated by atmospheric broadening, whereas the contribution of ENAs is negligible, as they are formed inside the bow shock from decelerated wind ions that are heated to high temperatures. Thus, within our modeling framework and assumptions, we find an insignificant dependence on the stellar wind parameters. Since the transit absorption can be modeled with typical stellar XUV and wind conditions, it is possible that the non-detection of the absorption in 2010 was affected by less typical stellar activity conditions, such as a very different magnitude and/or shape of the star's spectral XUV emission, or temporal/spatial variations in Ly$\alpha$ affecting the determination of the transit absorption.Comment: 22 pages, 19 figures, 4 tables; A&A, publishe

РАЗВИТИЕ СИСТЕМЫ КОНТРОЛЯ ЗА ХОДОМ СТРОИТЕЛЬНО-МОНТАЖНЫХ РАБОТ НА ОСНОВЕ КОМПЛЕКСНОГО ПРИМЕНЕНИЯ ПРОГРАММНЫХ ПРОДУКТОВ Primavera P6 Professional R8.3.2 И ArchiCAD 17.0.0

The paper considers application and development of information technologies while carrying out project management in construction. Organizational and technological support of works throughout its life cycle exerts an influence on quality and efficiency of successful implementation of the construction project. In order to achieve the project goal it is necessary perfectly to organize and plan works, distribute roles and responsibilities of the project participants, regulate composition and content of the project documentation. While analyzing technical and economic indices of construction organization activity and management systems operating in these organizations, conclusion has been made that market experience in functioning of operational management systems has not been adequately applied in practice of domestic construction organizations. Thus, introduction of integrated management systems for quality, costs, time parameters pertaining to project construction, their resource support will contribute to improvement of economic situation of construction organizations. The solution consists in application of up-to-date information technologies, maximum implementation of computer systems and programs in the sphere of production, creation of application software. It has been shown that it is necessary to develop a software model that provides a possibility comprehensively to apply information technology tools for monitoring progress of construction and installation works, systematization of information technology application that allow to control key parameters of construction and installation works, improvement of system for providing actual information in project implementation process. An example of complex application of software products Primavera P6 Professional R8.3.2 and ArchiCAD 17.0.0 is given in the paper.Рассмотрены вопросы применения и развития информационных технологий при управлении проектами в строительстве. На качество и эффективность успешной реализации строительного проекта оказывает влияние организационное и технологическое обеспечение работ на протяжении всего его жизненного цикла. Для достижения цели проекта необходимо четко организовать и спланировать работы, распределить роли и ответственность участников проекта, регламентировать состав и содержание проектной документации. При анализе технико-экономических показателей деятельности строительных организаций, а также систем управления, действующих в этих организациях, сделан вывод, что рыночный опыт функционирования систем оперативного управления не нашел достаточного применения в практике отечественных строительных организаций. Таким образом, внедрение в практику интегрированных систем управления качеством, издержками, временными параметрами строительства объектов, их ресурсным обеспечением будет способствовать улучшению экономического положения строительных организаций. Решение видится в применении новейших информационных технологий, максимальном внедрении компьютерных систем и программ в сферу производства, создании прикладных программных продуктов. Показана необходимость в разработке модели программного обеспечения, предоставляющего возможность комплексного применения инструментов информационных технологий в целях осуществления контроля над ходом строительно-монтажных работ, в систематизировании применения информационных технологий, позволяющих контролировать основные параметры строительно-монтажных работ, усовершенствовании системы обеспечения фактической информацией в процессе реализации проекта. Дан пример комплексного применени

Stellar Coronal and Wind Models: Impact on Exoplanets

Surface magnetism is believed to be the main driver of coronal heating and stellar wind acceleration. Coronae are believed to be formed by plasma confined in closed magnetic coronal loops of the stars, with winds mainly originating in open magnetic field line regions. In this Chapter, we review some basic properties of stellar coronae and winds and present some existing models. In the last part of this Chapter, we discuss the effects of coronal winds on exoplanets.Comment: Chapter published in the "Handbook of Exoplanets", Editors in Chief: Juan Antonio Belmonte and Hans Deeg, Section Editor: Nuccio Lanza. Springer Reference Work

Characterising exoplanets and their environment with UV transmission spectroscopy

Exoplanet science is now in its full expansion, particularly after the CoRoT and Kepler space missions that led us to the discovery of thousands of extra-solar planets. The last decade has taught us that UV observations play a major role in advancing our understanding of planets and of their host stars, but the necessary UV observations can be carried out only by HST, and this is going to be the case for many years to come. It is therefore crucial to build a treasury data archive of UV exoplanet observations formed by a dozen "golden systems" for which observations will be available from the UV to the infrared. Only in this way we will be able to fully exploit JWST observations for exoplanet science, one of the key JWST science case