Cosmic dust,planets and related problems

The study of micrometeorites which reach the Earth and of cosmic dust in general in inter-planetary space and in a planet's atmosphere may contribute significantly to the resolution of important astrophysical and geophysical problems, such as the origin and evolution of our solar system and the universe, and the problem of medium range weather forecasting (for about one month), in addition to the practical problem of NASA's “Man in Space” Programme. In this paper, the questions related to the fall of matter of cosmic origin on Earth, a possible mechanism for the capture of micrometeoric particles by the Earth and other planets of the solar system, indicated by the author, will be dealt with.     

Multiple light scattering: mean number of scatterings and related problems

This is a discussion of V. A. Ambartsumyan’s studies of the mean number of scatterings for photons in scattering media and of further work and development in this area, especially at Ambartsumyan’s St. Petersburg school. The following questions are discussed briefly: (a) the traditional method for calculating the number of scatterings from the source function and critiques of this method. (b) The equation for the number N(τ; τ₀ ) of scatterings for a photon born at optical depth τ in a plane layer of optical thickness τ₀ and its use for calculating the number of scatterings, averaged over the entire ensemble of photons for a medium with arbitrary internal sources. These questions are first considered for the case of monochromatic scattering, and then for scattering in a spectral line with complete frequency redistribution (CFR). (c) The mean path length for a resonance line photon in a scattering medium with CFR and continuum absorption: the basic equations and asymptotic behavior of an optically thick layer. (d) A review of calculations of and in media that are so thick that the CFR approximation breaks down and the effects of partial frequency redistribution (PFR) become dominant. The presentation is at a semiquantitative level in many parts of this paper, with stress on physical significance rather than the mathematics, through the use of approximate and asymptotic solutions. Translated from Astrofizika, Vol. 52, No. 1, pp. 29–45 (February 2009).     

On the jet of a young star RWAurA and related problems

Having compared images of a jet of the young star RWAurA obtained with an interval of 21.3 yr, we have found that the outermost knots of the jet have emerged approximately 350 years ago. We come up with arguments that the jet itself has appeared at the same time, and intensive accretion onto the star has begun due to rearrangement of its protoplanetary disk structure caused by the tidal effect of the companion RWAur B. More precisely suppose that intensification of accretion is a response to changing conditions in the outer-disk regions which has followed after the sound wave, generated by these changes, has passed the disk in the radial direction. In our opinion difference in the parameters of blue and red lobes of the RWAurA jet is a result of the asymmetric distribution of the circumstellar matter above and below the disk due to companion’s passage. It was found from the analysis of the RWAur historical light curve that deep and long-term (Δt > 150 days) light attenuations of RWAurA observed after 2010 had no precedents in the previous 110 years.We also associate the change in the character of photometric variability of the star with the rearrangement of the structure of inner (r < 1 AU) regions of its protoplanetary disk, and discuss why these changes have begun only 350 years after the beginning of the active accretion phase.     

Energy enigmas in the early Universe and related problems in Newtonian cosmology

Some paradoxical situations regarding the balance between the different forms of energy present and the velocities of expansion in the early stages of the big bang are discussed. Solutions are suggested in the framework of Newtonian gravitation.     

Some problems related to the origin of methane on Mars

The following problems related to the origin of methane on Mars have been considered. (1) Laboratory simulations of the impact phenomena confirm effective heterogeneous chemistry between the products of the fireball. This chemistry lowers the fireball freezing temperature from 2000 to 750 K for methane and to 1100 K for CO/CO₂. Production of methane on Mars by cometary impacts is 0.8% of the total production. A probability that the observed methane on Mars came from impact of a single comet is 0.0011. (2) The PFS observations of variations of methane on Mars require a very effective heterogeneous loss of methane. Heterogeneous effect of dust is half that of the surface rocks. Thermochemical equilibrium requires production, not loss, of methane. Existing kinetic data show a very low efficiency of heterogeneous reactions of methane. Highly reactive superoxide ions generated by the solar UV photons on the martian rocks cannot remove methane. The required efficiency of heterogeneous loss of methane on Mars is higher than that on Earth by a factor of ?1000, although the expected efficiency on Earth is stronger than that on Mars because of the liquid ocean and the abundant oxygen. All these inconsistencies may be removed if variations of the rock reflectivity contribute to the PFS observations of methane on Mars. The PFS data on H₂CO, HCl, HF, and HBr also raise doubts. (3) Although geologic sources of methane are possible, the lack of current volcanism, hydrothermal activity, hot spots, and very low seepage of gases from the interior are not favorable for geologic methane. Any proposed geological source of methane on Mars should address these problems. Some weak points in the suggested geologic sources are discussed. (4) Measurements of ¹³C/¹²C and D/H in methane would be difficult because of the low methane abundance. These ratios are mostly sensitive to a temperature of methane formation and cannot distinguish between biogenic and low-temperature geologic sources. Their analysis requires the carbon isotope ratio in CO₂ on Mars, which is known with the insufficient accuracy, and D/H in water, which is different in the atmosphere, polar caps, regolith and interior. Therefore, the stable isotope ratios may not give a unique answer on the origin of methane. (5) Ethane and propane react with OH much faster than methane. If their production relative to methane is similar to that on Earth, then their expected abundances on Mars are of a few parts per trillion. (6) Loss of SO₂ in the reaction with peroxide on ice is smaller than its gas-phase loss by an order of magnitude. The overall results strengthen the biogenic origin of martian methane and its low variability.     

About universes with scale‐related total masses and their abolition of presently outstanding cosmological problems

The most recently celebrated cosmological implications of the cosmic microwave background studies with WMAP (2006), though fascinating by themselves, do, however, create some extremely hard conceptual challenges for the present‐day cosmology. These recent extremely refined WMAP observations seem to reflect a universe which was extremely homogeneous at the recombination age and thus is obviously causally closed at the time of the cosmic recombination era. From the very tiny fluctuations apparent at this early epoch the presently observable nonlinear cosmic density structures can, however, only have grown up, if in addition to a mysteriously high percentage of dark matter an even higher percentage of dark energy is admitted as drivers of the cosmic evolution. The required dark energy density, on the other hand, is nevertheless 120 orders of magnitude smaller then the theoretically calculated value. These are outstanding problems of present day cosmology onto which we are looking here under new auspices. We shall investigate in the following, up to what degree a universe simply abolishes all these outstanding problems in case it reveals itself as an universe of constant total energy. As we shall show basic questions like: How could the gigantic mass of the universe of about 10⁸⁰ proton masses at all become created? – Why is the presently recognized and obviously indispensable cosmic vacuum energy density so terribly much smaller than is expected from quantum theoretical considerations, but nevertheless terribly important for the cosmic evolution? – Why is the universe within its world horizon a causally closed system? –, can perhaps simply be answered, when the assumption is made that the universe has a constant total energy with the consequence that the total mass density of the universe (matter and vacuum) scales with . Such a scaling of matter and vacuum energy abolishes the horizon problem, and the cosmic vacuum energy density can easily be reconciled with its theoretical expectation values. In this model the mass of the universe increases linearly with the world extension R_u and can grow up from a Planck mass as a vacuum fluctuation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Greenhouse gas emissions from a managed grassland

Managed grasslands contribute to global warming by the exchange of the greenhouse gases carbon dioxide, nitrous oxide and methane. To reduce uncertainties of the global warming potential of European grasslands and to assess potential mitigation options, an integrated approach quantifying fluxes from all three gases is needed. Greenhouse gas emissions from a grassland site in the SE of Scotland were measured in 2002 and 2003. Closed static chambers were used for N₂O and CH₄ flux measurements, and samples were analysed by gas chromatography. Closed dynamic chambers were used for soil respiration measurements, using infrared gas analysis. Three organic manures and two inorganic fertilizers were applied at a rate of 300 kg N ha⁻¹ a⁻¹ (available N) and compared with a zero-N control on grassland plots in a replicated experimental design. Soil respiration from plots receiving manure was up to 1.6 times larger than CO₂ release from control plots and up to 1.7 times larger compared to inorganic treatments (p<0.05). A highly significant (p<0.001) effect of fertilizer and manure treatments on N₂O release was observed. Release of N₂O from plots receiving inorganic fertilizers resulted in short term peaks of up to 388 g N₂O–N ha⁻¹ day⁻¹. However losses from plots receiving organic manures were both longer lasting and greater in magnitude, with an emission of up to 3488 g N₂O–N ha⁻¹ day⁻¹ from the sewage sludge treatments. During the 2002 growing season the cumulative total N₂O flux from manure treatments was 25 times larger than that from mineral fertilizers. CH₄ emissions were only significantly increased (p<0.001) for a short period following applications of cattle slurry. Although soil respiration in manure plots was high, model predictions and micrometeorological flux measurements at an adjacent site suggest that all plots receiving fertilizer or manure acted as a sink for CO₂. Therefore in terms of global warming potentials the contribution of N₂O from manure treatments becomes particularly important. There were considerable variations in N₂O and CO₂ fluxes between years, which was related to annual variations in soil temperature and rainfall.     

Greenhouse models of the atmosphere of titan

The greenhouse effect is calculated for a series of model atmospheres of Titan containing varying proportions of methane, hydrogen, helium, and ammonia. The pressure induced transitions of hydrogen and methane are the major sources of infrared opacity. For each model atmosphere we first computed its temperature structure with a radiative-convective equilibrium computer program and then generated its brightness temperature spectrum to compare with observed values. This comparison indicates that the methane-to-hydrogen ratio is 1_?.67⁺², the surface pressure is at least 0.4atm, and the surface temperature at least 150°K. In addition, except possibly close to the surface, the amount of ammonia is far less than the saturation vapor value. Large amounts of helium may also be present. Many of the successful model atmospheres have methane condensation clouds in the upper troposphere, which help reconcile spectroscopic gas abundances and the observed ultraviolet albedo of Titan with the gas amounts required for the greenhouse effect. The occurrence of large amounts of hydrogen may be a prerequisite for the occurrence of large amounts of methane in the atmosphere and vice versa. This hypothesis may help explain why Titan is the only satellite in our solar system known to have an atmosphere.     

Interstellar polyynes and related species

The existence of the polyynes — molecules consisting essentially of long chains of carbon atoms — in the interstellar medium is a discovery that appears to be critical to our understanding of interstellar chemistry. The family relationships of these species to other interstellar species are explored as are their significance to theories of interstellar chemistry. Methods for deducing the numbers of related molecules are presented.     

Gamma-ray binaries and related systems

After initial claims and a long hiatus, it is now established that several binary stars emit high- (0.1–100 GeV) and very high-energy (>100 GeV) gamma rays. A new class has emerged called “gamma-ray binaries”, since most of their radiated power is emitted beyond 1 MeV. Accreting X-ray binaries, novae and a colliding wind binary (η Car) have also been detected—“related systems” that confirm the ubiquity of particle acceleration in astrophysical sources. Do these systems have anything in common? What drives their high-energy emission? How do the processes involved compare to those in other sources of gamma rays: pulsars, active galactic nuclei, supernova remnants? I review the wealth of observational and theoretical work that have followed these detections, with an emphasis on gamma-ray binaries. I present the current evidence that gamma-ray binaries are driven by rotation-powered pulsars. Binaries are laboratories giving access to different vantage points or physical conditions on a regular timescale as the components revolve on their orbit. I explain the basic ingredients that models of gamma-ray binaries use, the challenges that they currently face, and how they can bring insights into the physics of pulsars. I discuss how gamma-ray emission from microquasars provides a window into the connection between accretion–ejection and acceleration, while η Car and novae raise new questions on the physics of these objects—or on the theory of diffusive shock acceleration. Indeed, explaining the gamma-ray emission from binaries strains our theories of high-energy astrophysical processes, by testing them on scales and in environments that were generally not foreseen, and this is how these detections are most valuable.     

Vertical profile of H2SO4 vapor at 70-110 km on Venus and some related problems

The vertical profile of H₂SO₄ vapor is calculated using current atmospheric and thermodynamic data. The atmospheric data include the H₂O profiles observed at 70-112 km by the SOIR solar occultations, the SPICAV-UV profiles of the haze extinction at 220 nm, the VeRa temperature profiles, and a typical profile of eddy diffusion. The thermodynamic data are the saturated vapor pressures of H₂O and H₂SO₄ and chemical potentials of these species in sulfuric acid solutions. The calculated concentration of sulfuric acid in the cloud droplets varies from 85% at 70 km to a minimum of 70% at 90 km and then gradually increasing to 90-100% at 110 km. The H₂SO₄ vapor mixing ratio is ∼10⁻¹² at 70 and 110 km with a deep minimum of 3 × 10⁻¹⁸ at 88 km. The H₂O-H₂SO₄ system matches the local thermodynamic equilibrium conditions up to 87 km. The column photolysis rate of H₂SO₄ is 1.6 × 10⁵ cm⁻² s⁻¹ at 70 km and 23 cm⁻² s⁻¹ at 90 km. The calculated abundance of H₂SO₄ vapor at 90-110 km and its photolysis rate are smaller than those presented in the recent model by Zhang et al. (Zhang, X., Liang, M.C., Montmessin, F., Bertaux, J.L., Parkinson, C., Yung, Y.L. [2010]. Nat. Geosci. 3, 834-837) by factors of 10⁶ and 10⁹, respectively. Assumptions of 100% sulfuric acid, local thermodynamic equilibrium, too warm atmosphere, supersaturation of H₂SO₄ (impossible for a source of SO_X), and cross sections for H₂SO₄·H₂O (impossible above the pure H₂SO₄) are the main reasons of this huge difference. Significant differences and contradictions between the SPICAV-UV, SOIR, and ground-based submillimeter observations of SO_X at 70-110 km are briefly discussed and some weaknesses are outlined. The possible source of high altitude SO_X on Venus remains unclear and probably does not exist.     

Solar and stellar flares: Questions and problems

Although progress has been made in understanding certain aspects of the physics of solar and stellar flares, there are a number of topics which, in the author's opinion, still pose a problem. We summarize these topics here.     

Infrared spectra of quasars and related objects

An attempt is made to explain the infrared radiation observed for several quasars and Seyfert galaxies as thermal radiation of a dust envelope surrounding the cores of these objects. Two kinds of dust particles (graphite and silica) are taken into consideration. It is shown that the observed spectral behaviour and the luminosity in the infrared can be introduced as thermal radiation of silica grains. In the case of 3C 273 one finds that the radius of the dust envelope is about 50 pc and the total mass of dust is about 600M _⊙.     

Restricted quantum-mechanical three-body problems

Eigenvalues and normalized wave functions of an electron are derived in the field of a generalized dipole with chargesZ ₁ andZ ₂ (Z ₁+Z ₂ 0) in the asymptotic region up to the third order (inr ₂) where the distance,r ₂, between the two charges is small. These asymptotic wave functions render it possible to calculate the asymptotic expansion for the coefficients of a coupled infinite system of second order differential equations arising from a perturbative (analytic) solution to the Schrödinger equation of helium-like ions if the nuclear charge is not less than 2.     

Restricted quantum-mechanical three-body problems

A new method is presented in a general form to solve the Schrödinger equation of helium-like ions. The wave function is expanded in terms of the eigenfunctions of a moving electron in the field of two Coulombic ions which are fixed in space. This makes the method similar to the Dirac perturbation theory (perturbation theory for time-dependent problems). In the present method an infinitely coupled system of infinitely many second-order ordinary differential equations must be solved instead of one second-order partial differential equation of three variables. The nature of the singular points and boundary conditions are discussed and some general relations are given which are useful for the numerical treatment.     

The problems of ageing

I present a brief overview of observational, modeling and theoretical issues related to ageing calculations based on spectral steepening. These include problems such as inhomogeneous magnetic fields, diffusion of relativistic particles, confusion from multiple particle populations and particle acceleration. Although some of the effects are only of order unity, others call into question the entire ageing paradigm. I refer to and show some data illustrating these problems and make a few recommendations about how we should proceed given these uncertainties.     

Restricted quatum-mechanical three-body problems

On the basis of a perturbative procedure in which the eigenfunctions of a helium-like ion are expanded in the Hilbert space built up from the eigenfunctions of an electron in two fixed Coulomb charges,all asymptotic eigenfunctions are constructed for the Schrödinger equation of helium-like ions. If the nuclear chargeZ ₁ is not less than 2, then our asymptotic considerations clarify the singularities of the Schrödinger equation of a helium-like ion (atr ₁=0, ,r ₂=0, ,r ₁₂=0, ), while in the case ofZ ₁=1 (negative hydrogen ion)r ₂=0 will not be treated in this paper. The established order (inr ₂) of asymptotics at 0 or in an exceptional case the zeroth-order term of the functions (actually the coefficients of an expansion of the desired eigenfunctions) as one of the electron coordinates (r ₂, the distance of the two fixed Coulomb charges, a parameter of the set of the basic functions) enables us to classify the eigenfunctions of a helium-like ion. This classification resembles the classification scheme for one-electron configurations. The asymptotics forr ₂ indicate bounded, pseudobounded (auto-ionizing) and free states. (Doubly ionized continuum states are not discussed here.) The use of the asymptotic solutions is indicated for the complete solution of the problem which may be either numerical integration or a variational procedure.Neutral muonic helium is included in the discussion.     

Restricted quantum-mechanical three-body problems

The Schrödinger equation is solved if an electron moves in the field of chargesZ ₁ andZ ₂ which are fixed in space. The wave function is expanded in power series, the eigenvalues are given graphically and partly in tabular form. The asymptotic behaviour of the eigenvalues is discussed when the distance of the two fixed charges is small and large. Some consequences are drawn on hydrogen line broadening, shift andgrenzkontinua. Further utilization of the calculations is indicated. The mathematical appendix helps to clarify some technical details of the calculations.