Low Surface Brightness (LSB) galaxies are dominated by dark matter. High-resolution rotation curves suggest that their total mass-density distributions are dominated by constant density cores rather than the steep and cuspy distributions found in Cold Dark Matter (CDM) simulations. the data are best described by a model with a soft core with an inner power-law mass-density slope α = 0.2 ± 0.2. However no single universal halo profile provides an adequate description of the data. the observed mass profiles appear to be inconsistent with ACDM.

A general scheme of evolution of close binaries is outlined. Many types of observed systems are classified according to their evolutionary status. Present theory can account reasonably well for the mass transfer between the two components. There is no satisfactory theory of mass and angular momentum loss from binary (as well as single) stars. Most close binaries sooner or later should develop extended common envelopes. A loss of a common envelope may remove a large fraction of mass and most of angular momentum from a binary, and leave as a remnant a very short period and highly evolved system. Binary nuclei of planetary nebulae, cataclysmic variables and some X-ray binaries are produced this way.

I shall present here a picture of the evolution of close binary systems (CBS) as it is understood now. This is not intended to be a review, and no attempt has been made to make the list of references complete. Usually I shall refer the first paper on a given subject and/or one of the recent ones, where a large number of other references can be found. There are many reviews and proceedings of various symposia that deal with close binaries. Here are some: Annual Review of Astronomy and Astrophysics (9, 183, 14, 119, 15, 127, 16, 171, 241), IAU Symposia No. 73, 83, 88, IAU Colloquia No. 42, 46, 53. I shall try to emphasize what is known and what is not known, and how various observed systems fit into the theoretical evolutionary scheme. Because of my background I shall give more references to theoretical papers. Nevertheless, I am convinced that it was the theory of close binaries that was guided in its development by the observations, not other way around. In fact the theory predicted very few new phenomena and very few new types of binaries. But it managed to account, at least qualitatively, for the major evolutionary processes, and made it possible to arrange the observed systems into the evolutionary sequences.

It is possible to deduce information concerning large scale coronal magnetic field patterns from the knowledge of the location of radioburst sources.

As the method concerns active centers responsible for corpuscular emission, the knowledge of these structures may have important implications in the understanding of corpuscular propagation in the corona and in the interplanetary medium.

During their main sequence evolution, massive stars can develop convective regions very close to their surface. These regions are caused by an opacity peak associated with iron ionization. Cantiello et al. (2009) found a possible connection between the presence of sub-photospheric convective motions and small scale stochastic velocities in the photosphere of early-type stars. This supports a physical mechanism where microturbulence is caused by waves that are triggered by subsurface convection zones. They further suggest that clumping in the inner parts of the winds of OB stars could be related to subsurface convection, and that the convective layers may also be responsible for stochastic excitation of non-radial pulsations. Furthermore, magnetic fields produced in the iron convection zone could appear at the surface of such massive stars. Therefore subsurface convection could be responsible for the occurrence of observable phenomena such as line profile variability and discrete absorption components. These phenomena have been observed for decades, but still evade a clear theoretical explanation. Here we present preliminary results from 3D MHD simulations of such subsurface convection.

We describe some aspects of implementing star cluster simulations on HARP. The code NBODY4 employs the Hermite scheme with hierarchical block-steps for direct integration. The algorithms have been optimized for parallel processing with the eight pipeline HARP-2 delivering a peak performance of about 1.7 Gflops for N = 104 particles. Hard binaries are studied by KS regularization which also uses the Hermite scheme, whereas strong interactions between 3–5 particles are treated by chain regularization. Astrophysical processes modelled include mass loss by stellar evolution, two-body tidal interaction, Roche lobe mass transfer, common envelope evolution, magnetic braking and gravitational radiation. Consistent values of stellar radii and evolution type are obtained by fast look-up. A new formulation of collision outcomes yields blue stragglers and other exotic objects. Some recent results for an open cluster model are presented.

Eclipsing binaries can in principle provide additional constraints to facilitate asteroseismology of one or more pulsating components. We have identified 94 possible eclipsing binary systems in a sample of over 1800 stars observed in long cadence as part of the Kepler Guest Observer Program to search for γ Doradus and δ Scuti star candidates. We show the results of a procedure to fold the light curve to identify the potential binary period, subtract a fit to the binary light curve, and perform a Fourier analysis on the residuals to search for pulsation frequencies that may arise in one or both of the stellar components. From this sample, we have found a large variety of light curve types; about a dozen stars show frequencies consistent with δ Sct or γ Dor pulsations, or light curve features possibly produced by stellar activity (rotating spots). For several stars, the folded candidate ‘binary’ light curve resembles more closely that of an RR Lyr, Cepheid, or high-amplitude δ Sct star. We show highlights of our results and discuss the potential for asteroseismology of the most interesting objects.

Presupernova models of massive stars are presented and their explosion by “delayed neutrino transport” examined. A new form of long duration Type II supernova model is also explored based upon repeated encounter with the electron-positron pair instability in stars heavier than about 60 M⊙. Carbon deflagration in white dwarfs is discussed as the probable explanation of Type I supernovae and special attention is paid to the physical processes whereby a nuclear flame propagates through degenerate carbon.

We provide a brief overview of properties of transequatorial loops (TLs) and show that some TLs fit the description of a loop, while others appear to be the magnetic separators.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We examine whether the dark, orbitally-leading hemisphere of Saturn's satellite Iapetus might be coated by debris from low-albedo Phoebe, which orbits retrograde well exterior to Iapetus. Using simplified analytical models along with more complete numerical integrations, we follow the paths of various-sized particles launched gently off Phoebe following collisions with interplanetary and interstellar meteoroids. Micron grains can quickly reach Iapetus since (due to solar radiation) they trace elliptical orbits; larger grains may only hit after their more-circular orbits collapse due to Poynting-Robertson drag; few very large and very small Phoebe grains strike Iapetus. Despite some inconsistencies with observations, we conclude that Phoebe may possibly be the agent that has darkened Iapetus.

The explosion mechanism of core-collapse supernovae is a long-standing problem in stellar astrophysics. We briefly outline the main contenders for a solution and review recent efforts to model core-collapse supernova explosions by means of multi-dimensional simulations. Focusing on the neutrino-driven mechanism, we summarize currents efforts to predict supernova explosion and remnant properties.

There are about 70 Galactic supernova remnants (SNRs) that are now confirmed or suggested to be in physical contact with molecular clouds (MCs) with six kinds of evidence of multiwavelength observations. Recent detailed CO-line spectroscopic mappings of a series of SNRs reveal them to be in cavities of molecular gas, implying the roles the progenitors may have played. We predict a linear correlation between the wind bubble sizes of main-sequence OB stars in a molecular environment and the stellar masses and discuss its implication for supernova progenitors. The molecular environments of SNRs can serve as a good probe for the γ-rays arising from the hadronic interaction of the accelerated protons, and this paper also discusses the γ-ray emission from MCs illuminated by diffusive protons that escape from SNR shocks.

Rapidly rotating stars are readily produced in binary systems. An accreting star in a binary system can be spun up by mass accretion and quickly approach the break-up limit. Mergers between two stars in a binary are expected to result in massive, fast rotating stars. These rapid rotators may appear as Be or Oe stars or at low metallicity they may be progenitors of long gamma-ray bursts.

Given the high frequency of massive stars in close binaries it seems likely that a large fraction of rapidly rotating stars result from binary interaction. It is not straightforward to distinguish a a fast rotator that was born as a rapidly rotating single star from a fast rotator that resulted from some kind of binary interaction. Rapidly rotating stars resulting from binary interaction will often appear to be single because the companion tends to be a low mass, low luminosity star in a wide orbit. Alternatively, they became single stars after a merger or disruption of the binary system during the supernova explosion of the primary.

The absence of evidence for a companion does not guarantee that the system did not experience binary interaction in the past. If binary interaction is one of the main causes of high stellar rotation rates, the binary fraction is expected to be smaller among fast rotators. How this prediction depend on uncertainties in the physics of the binary interactions requires further investigation.

An overview is given about recent developments and results of comprehensive simulations of magneto-convective processes in the near-surface layers and photosphere of the Sun. Simulations now cover a wide range of phenomena, from whole active regions, over individual sunspots and pores, magnetic flux concentrations and vortices in intergranular lanes, down to the intricate mixed-polarity structure of the magnetic field generated by small-scale dynamo action. The simulations in concert with high-resolution observations have provided breakthroughs in our understanding of the structure and dynamics of the magnetic fields in the solar photosphere.

The basic physics of model atmospheres for Luminous Blue Stars (LBS) are discussed. The discussion comprises the model description of both subsonic photospheres and supersonic winds and the application of model calculations for the purpose of quantitative spectroscopy.

A general review is given of the content and distribution of interstellar gas within galaxies. The constancy of the ratio N(He)/N(H), independent of galaxy type (spirals and irregulars), is discussed and the possible mechanisms for this constancy are considered. The helium abundance does not vary across the disk of spirals, although nitrogen and possibly other elements do.

The gross features of the neutral hydrogen distribution in our Galaxy and other systems are described. In spirals, the peak of the radial distribution of Hi is located well away from the optical center. This is not the case for irregular-type systems. A possible correlation of the relative location of the maxima of Hi and Hii distributions with galaxy type is described. Many spirals studied with high enough relative angular resolution show concentrations of Hi in their outermost regions. These may be due to hydrogen companions or warps in the hydrogen plane. Hydrogen ‘bridges’ are described and a new example for the triple system M81–M82–NGC 3077 is given. This latter case may be an extreme example of distortion by companion galaxies of the Hi associated with a massive galaxy.

The neutral hydrogen content of a galaxy and its correlation with other integral properties is discussed. The absorption profile due to hydrogen associated with the radio galaxy Centaurus A is given. Comparison of optical and 21-cm measurements of galaxian redshifts shows excellent agreement over the radical velocity range −400 to + 5200 km s−1. There is, however, a systematic difference between 21 cm and optical redshifts over the range ∼ 1200 to ∼ 2400 km s−1 for optical values based on blue-sensitive spectra. The difference, ∼ 100 km s−1, is most likely due to blending of galaxian and night sky H and K absorption lines. The Hubble Constant is derived from a redshift-21 cm flux relation. Values in the range 78 to 109 km s−1 Mpc−1 are derived. A value of 97 kms−1 Mpc−1 is favored.

Integrated optical components (mostly single-mode fibers and couplers) can be used to achieve several functions that are needed in interferometry: coherent beam transportation and recombination, pathlength modulation and control for fringe tracking and double Fourier interferometry, spatial filtering of the wavefront and interferogram calibration. Their potential is assessed and the main problems encountered in their implementation are discussed: dispersion, polarization behavior, and especially starlight injection.

Most treatments of lower hybrid waves include either electromagnetic or warm-plasma effects, but not both. Here we compare numerical dispersion curves for lower hybrid waves with a new analytic dispersion relation that includes both warm and electromagnetic effects. Very good agreement is obtained over significant ranges in wavenumber and plasma parameters, except where ion magnetization effects become important.

It is suggested that aerodynamic forces played a significant role in the selective accumulation of chondrules on asteroids moving with respect to the gas in a primeval solar nebula. Particles smaller than millimeter chondrules would sweep by an asteroid moving in a critical velocity range, whereas larger particles could be accumulated by impact. Theory and calculation cover the case of subsonic velocity and asteroidal diameter up to 50 km for a nebula density up to 10-6 g/cm3, or higher for smaller asteroids.

Unusually long activity of the Taurid meteor complex, extending over 3-5 months according to new estimations based on various orbital similarity criteria, has been evoking controversies about the possible origin and dynamical evolution of this unique complex of meteor streams. It even casts doubts on the reality of the extension of the complex. In the present paper orbital elements and the extension of the Taurid meteor complex are re-examined on the bases of the most precise photographic meteor orbits available from the IAU Meteor Data Center in Lund. The results are evaluated and discussed from the viewpoint of various proposals on the origin and dynamical evolution of the complex.