We report on the discovery of a supermassive binary black-hole (SBBH) system in the radio galaxy 0402+379, with a projected separation between the two black holes of just 7.3 pc. This is the most compact SBBH pair yet imaged by more than two orders of magnitude. These results are based upon multi-frequency imaging using the Very Long Baseline Array (VLBA) which reveal two compact, variable, flat-spectrum, active nuclei within the elliptical host galaxy of 0402+379. Multi-epoch observations from the VLBA also provide constraints on the total mass and dynamics of the system. The two nuclei appear stationary while the jets emanating from the weaker of the two nuclei appear to move out and terminate in bright hot spots. The discovery of this system has implications for the number of compact binary black holes that might be sources of gravitational radiation. The VLBI Imaging and Polarimetry Survey (VIPS) currently underway should discover several more SBBHs.

The term “heating” is used loosely to refer to a range of processes that result in an increase in velocity dispersion with age for subgroups of disk stars. We briefly summarise the observational basis for studies of disk heating and show that qualitative differences exist between the evolution of the in-plane and vertical motions. Ways to discriminate between various heating scenarios are discussed; the most recent galaxy merger simulations may in fact suggest that discrimination on purely kinematic grounds might be unfeasible, even with large samples of stars with excellent ages.

The idea of communicating cultural concepts in a SETI message, suggesting that analogy may be a useful tool, is developed in this paper in a systematic way, aiming at the construction of an effective message with wide cultural content. Here, I discuss both materials and methods in relation to three questions. Firstly, which of the main concepts of our culture are likely to be communicated in this way? Secondly, is the conceptual cluster (Dutil, 2004) sufficient as a basis to apply the analogical methodology or should it be extended further? And lastly, what is the possible contribution of the different kinds of logic (i.e. classical, mathematical, fuzzy and so on) and which are their relationships (if any) with analogy?

In this paper we present the statistical analysis of historical light curves of 8 old novae, performed through a Fourier analysis on ~ 1600 no-equispaced (in the time) observations published by Steavenson between 1921 and 1953. The results seems to support the existence of a semiregular variability on typical timescales of 50d ÷ 100d and amplitude of ~ 0.3 ± 0.1 magnitudes.

At present the largest body of data concerning the photometric behaviour of novae at minimum, is due to the pioneering works by Steavenson (1920→1950) and also to Robinson’s compilation (1975) of 33 preeruption lightcurves of novae.

Besides testing the evolutionary models, such as the Hibernation Scenario (Shara et al. 1986), the importance of very long term observations of novae at minimum, has been recently pointed out by Bianchini (1987) and Warner (1988) in close connection to the possible detection of solar-type cycles of activity of the secondary. In spite of these considerations an interesting body of ~ 1000 homogenous observations of 5 posteruption lightcurves provided by Steavenson between 1920 to 1950 (published on M.N.R.A.S) has been neglected and only recently recovered (Delia Valle 1988).

The aim of our analysis is:

1. a) to verify possible presence of Dwarf Nova activity

2. b) to confirm on the basis of a larger sample of objects, the existence of semiregular variability as observed in Q Cyg 1876 (Shugarov 1983) and v841 Oph (Della Valle and Rosino 1987).

In this contribute we present only the preliminary results of our Fourier’s analysis, performed by adopting the procedure suggested by Deeming (1975) to analyse data taken at unequally spaced time intervals, whereas a more complete analysis will be presented in a forthcoming paper.

Magnetic fields are crucial to the generation of turbulence and the dynamics of accretion and energy dissipation in accretion disks. Nevertheless, until now, there has been no self-consistent analytic formalism that puts the evolution of turbulent magnetic fields on the same footing as other dynamical processes such as mass flow and energy generation. We have developed a self-consistent framework for turbulent, magnetized accretion disks with the aim of studying the processes that power hot coronae. Utilizing this framework we have identified the possible magnetic sources of power for the coronae of black hole accretion disks. The most promising is the Poynting flux associated with the azimuthal-vertical magnetic stress. We also determine how the emission from the disk is modified by the processes that power the corona and related winds.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

This report is organized according to twelve subjects of interest in modern celestial mechanics. Emphasis is placed on the results of an exhaustive literature search in which assistance was received from several members of Commission 7. The impetus on celestial mechanics by space projects, by new observational techniques and by the use of high speed electronic computers continued to be of considerable importance. The fact that celestial mechanics became an experimental science is still too recent to be fully evaluated. The high accuracy of radar and laser observations, the new analytical and numerical techniques, the recent sophisticated statistical orbit determination methods and many other results achieved during the past three years suggest that celestial mechanics is an exploding field of science in which new and exciting results emerge. Celestial mechanics is influencing other fields of scientific endeavor and is intimately connected and embedded in almost all areas of modern astronomy and space research.

This article summarises the subject matter of Special Session 3 at IAU General Assembly XXVII in Rio de Janeiro, Brazil, which took place on August 6-7, 2009. In it, we overview the state of Astronomy in Antarctica as it is in 2009. Significant astronomical activity is now taking place at four stations on the Antarctic plateau (South Pole, Domes A, C & F), as well as at the coastal station of McMurdo.

We present the first results of a series of Monte-Carlo simulations investigating the imprints of a central black hole on the core structure of globular clusters. We investigate the three-dimensional and the projected density profile of the inner regions of idealized as well as more realistic globular cluster models, taking into account a stellar mass spectrum, stellar evolution and allowing for a larger, more realistic, number of stars than was previously possible with direct N-body methods. We compare our results to other N-body simulations published previously in the literature.

The period–luminosity (PL) relation of the Cepheid variable stars is the most reliable primary distance indicator for nearby galaxies, and serves as the foundation of the extragalactic distance scale, providing the firm calibration for various secondary distance indicators. However, a major disadvantage of the Cepheid distance scale is that it can only be applied to late–type systems with recent or current star formation. An alternative distance indicator is a Pop II, tip of the red giant branch (TRGB) method, which is extremely attractive because of its applicability to all morphological types of galaxies. As long as a metal–poor RGB stars are present in abundant numbers, the distance can be estimated with an accuracy that is as good as that of the Cepheid PL relation.

Significant improvements in our understanding of the physical conditions in active galaxies requires the development of sophisticated models that can predict in detail the emission from the nucleus. Accurate measurements of both the UV continua and the many weak diagnostic UV lines provide critical calibrations for such models.

Rigorous comparisons of the HST FOS and IUE UV flux calibrations have so far been performed using spectrophotometric standard star spectra. These calibration observations have precision acquisition sequences and the spectra have very high S/N. Such data are not representative of typical FOS observations of an AGN, which often cannot be acquired with the same precision as standard stars, especially for pre-COSTAR data. Furthermore, the UV flux from a typical AGN is several magnitudes fainter than from a spectrophotometric standard star, and is more representative of typical non-stellar fluxes. Flux-dependent effects (in either FOS or IUE) may need to be considered at these lower flux levels.

The characteristics of large-scale two-ribbon flares and dark points observed in He I λ10830 are summarized and compared with observations of these phenomena at other wavelengths and with the underlying magnetic field.