A revised reference catalogue of galactic supernova remnants

This paper reviews observations made over recent years that have led to the identification of many new galactic supernova remnants (SNRs) and have clarified the nature of several objects that had been thought to be SNRs. A revised reference catalogue of 155 galactic SNRs is presented, complete with notes on the newly identified remnants, those objects no longer thought to be SNRs, the questionable objects in the catalogue, and possible candidate SNRs. The selection effects applicable to the identification of galactic SNRs are discussed, with particular reference to the limitations that they impose upon statistical studies.     

Distribution of novae in height above the galactic plane

To test the hypothesis about the existence of two different subsystems of novae in the Galaxy, disk and bulge novae, we have constructed the spatial distribution of 64 novae in z coordinate. A large number of fast novae, believed to be disk novae, are at a considerable distance from the Galactic plane (up to z ～ 3700 pc), which cannot be explained by the photometric measurement errors. Slow novae, believed to be bulge novae, show a higher concentration to the Galactic plane (z ? 1700 pc). The application of the Kolmogorov-Smirnov test has shown that the hypothesis of two populations is valid with a probability of 95.6%.     

A possible observational constraint on the production of lithium by galactic novae

Recent computations (D'Antona and Mazzitelli, 1982), together with the general scheme of evolution of cataclysmic binaries (CBs), lead to conclude that the secondaries in those CBs having periods shorter than 4.5 hr have a large³He content in the envelope, ranging from 10^–4 (P=4.5 hr) to >2×10^–3 (P=3 hr) in mass fraction, if the nova systems have an age of some billion years. The consequence on the frequency of novae outbursts is shortly examined. If lithium is produced by galactic novae, the⁷Li content of old disk stars should be very close to the Population II content.Presented at the 5th European Workshop on White Dwarfs, Kiel, 1984.     

Determining the photometric parameters of galactic novae from visual light curves

Based on visual estimates by AAVSO observers, we have constructed light curves for 80 Galactic novae flared up in 1986–2006 and determined the photometric parameters m _vis(max), t ₂, and t ₃ for 64 novae. Using the empirical relation M _V (max) = ?10.66(±0.33) + 2.31(±0.26) × log t ₂, we have obtained the absolute magnitudes at maximum and apparent distance moduli of the novae.     

A brief overview of dwarf novae and X-ray novae

Dwarf novae and X-ray novae have proven to be important in advancing our knowledge of accretion disk physics, or at least of posing challenging questions. The myriad behavior of the various classes and subclasses, including aspects associated both with outburst and quiescence, are constantly providing stimulus to our efforts at modeling accretion disks. I will briefly review some of the main properties of these two classes of objects – including discussions of their outburst characteristics and physical differences. I will also try to point out areas in which we do not have a detailed understanding of the basic model within which to interpret the observations.     

The Kukarkin-Parenago relation for dwarf novae and novae

The period-amplitude relation and the period-energy relation for dwarf novae and novae are discussed. The total outbursts energy is shown to be a more suitable characteristic of the outburst than its amplitude.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

A comparison catalogue ofHii-regions

For complete information about the apparent distribution ofHii-regions along the whole galactic equator a Catalogue of 698 known emission nebulae is given on the basis of 13 lists and catalogues of these objects. The main catalogue used for the northern sky was that of Sharpless (1959) including 313 objects while the coverage of the southern sky can be characterized by a greater number of smaller catalogues represented in the first place by that of Rodgerset al. (1960) and that of Gum (1955). ForHii-regions, only optical data were taken into account.Where several authors describe the complex of nebulosities a more detailed specification of objects is preferred. The objects in the Catalogue are listed according to their right ascensions for 1950. As only three catalogues applied here give also the objects out of the belt ±15° around the galactic equator, the Catalogue is divided into two parts. The first (main) part contains 667 objects lying within this belt, the second contains 31 objects lying outside it. A Summary Table listing the objects from the two parts according to their galactic longitudes involving, in addition, the 50-yrs precession for every object is also added.An attempt was made not to repeat contingent errors present in the source-catalogues. The maps of the POSS were often used. Coincidences with SNR and planetaries were sought for independently of identifications given in the source-catalogues. The list of objects from the source-catalogues ofHii-regions excluded as SNR, planetaries and galaxies is also given.Astrophysics and Space Science Review Paper.     

Continuing galactic formation: A new concept of galactic evolution

A new theory for galactic arm formation shows the arms to be continually eminating from the galactic nucleus due to a continual influx of cosmic dust. In the neighborhood of the nucleus the problem is treated as a fluid flow and a simple solution is given using conservation of momentum. When rotational dynamics are included the spinning arm system is the result. This solution resolves the problem of the missing mass, accounts for warped disk galaxies and gives a probable source for the gravity waves measured by Weber which eminate from our galactic center. Reversal of arm direction is demonstrated and examples of such reversals are cited. An approximate theoretical estimate of the age of our Sun is found to be in good agreement with radio isotope dating. A general result shows why twin star systems are in such great abundance in a galaxy. It gives a model of galactic evolution which begins with only a single massive nucleus with the collapsing gas clouds forming the arms.     

A classification of galactic collisions

The effects of collisions between two galaxies on the test galaxy considered are classified as follows — Type A: the changes in the size and mass of the test galaxy are both negligible; Type B: There is significant increase in the size (at least 10%) or decrease in the mass (at least 1%) of the test galaxy or in both; Type C: The test galaxy becomes a component of a double galaxy by tidal capture; Type D: The test galaxy is disrupted by the tidal forces of the field galaxy.The type of collision is given as a function of the distance and speed at closest approach and also as a function of the initial impact parameter and speed at infinite separation of the two galaxies for two density models of the galaxies. Collisions in which the two galaxies do not penetrate each other are generally of type A while slow interpenetrating collisions are generally of type B. Types C and D occur in head-on or nearly head-on collisions if the relative speed of the two galaxies is sufficiently small; the former is favoured if the two galaxies do not differ appreciably in mass and density distribution. If one of the two galaxies is considerably less massive or less centrally concentrated than the other, it will be disrupted in slow close collisions.     

Photometry of recent novae and supernovae

Light curves of recent novae and the supernova 1991T are presented primarily to demonstrate the paucity of photoelectric or calibrated CCD measurements, particularly in the critical maximum phase. There is a an opportunity for a very useful contribution to the study of these objects by photometrists with modest telescopes, particularly if they can respond quickly.     

The outbursts of classical and recurrent novae

In this review, I present our current state of knowledge regarding both Classical Nova and Recurrent Nova systems. Two particular objects (V1974 Cyg and RS Oph) are chosen to illustrate the range of phenomena that may be associated with their outbursts. The wider importance of nova research is emphasised and some of the most pressing unsolved problems are summarised (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A model for galactic centres

A rotating Supermassive Magnetized Disk is proposed as a model for all the violent phenomena occurring in the nuclei of galaxies, in the form of quasars, Lacertids, radio galaxies, Seyferts, exploding galaxies, etc. The cold disk feeds a fast-rotating supermassive core (some 10³ Schwarzschild radii in extent), which emits (1) an unsteady thermal wind of filamentary geometry, (2) Low-Frequency magnetic Waves, and (3) relativistic electrons and positrons. The latter reach high -factors by phase-riding the LFWs, emit synchro-Compton radiation on crossing scattered waves (from -ray energies down to radio frequencies), and are eventually focused into two antipodal relativistic beams by their frozen-in toroidal magnetic field. Torsional oscillations between the core and disk give rise to a pulsed injection, and a breathing double-onion shape of the LFW windzone can explain the superluminal jetlike appearance. A big nuclear explosion ends each duty cycle, but many smaller explosions prevent the settling core from collapsing. In this model, the helium production of galactic centres is comparable to the observed cosmic helium.     

Observations of eclipsing dwarf novae

High Speed Photometry of four eclipsing dwarf novae, z Cha, OY Car, HT Cas and IP Peg, is used to determine the orbital parameters and the masses of the two stars in each system. The mass ratio, q, and inclination, i, are found by constraining theoretical stream trajectories (Lubow and Shu 1975) to pass through the observed light centre of the bright spot eclipse. The light centre is defined as the point corresponding to the half flux points in the ingress and egress of the eclipse of the compact part of the bright spot. The theoretical stream width indicates that the centre of the stream must intersect the bright spot close to this point.The length of ingress and egress in the primary eclipse, constrains the radius of the central object relative to the orbital separation. The shape of this eclipse and the temperature of the central objects in z Cha, OY Car and HT Cas imply that the measuredPaper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

A photometric catalogue of visual and multiple stellar systems

Summary The catalogue gives the parameters of theUBV, uvby, and Geneva photometries for more than 200 stars. It gives also the first statistics with respect to the different caracteristics of visual systems: separation, difference of the magnitude of components,... etc. For 11713 components of stellar systems the catalogue, in its actual form, gives the parameters of theUBV, uvbyβ and Geneva photometric systems. A concise statistics presents the distribution of the stars in the different photometric systems and the relations between the difference in the magnitudes and separation of the components. CNRS UA 040389.     

Spectroscopic studies of three novae

We present our spectroscopic observations of the novae V1425, V1493, and V1494 Aql carried out with the 125-cm telescope at the Crimean Station of the Sternberg Astronomical Institute in the wavelength range 4000–11000 Å. We measured the emission-line intensities, determined the nova shell expansion velocities from the line profile FWHMs and components, and estimated the interstellar reddening from the first members of the Balmer series. The chemical composition of the nova shells is analyzed. Nitrogen and oxygen were found to be overabundant in V1425 and V1494 Aql; the helium abundance turned out to be normal in the two stars.     

The nature of recurrent novae

The observational properties and outburst histories of each member of the small class of recurrent novae are reviewed, with the objective of identifying the outburst mechanisms for these systems. Examples are found of both accretion-powered outbursts (T CrB and RS Oph) and thermonuclear-powered outbursts (T Pyx and U Sco). Outburst properties which might be used in future to distinguish between these mechanisms are identified. Many erstwhile recurrent novae (VY Aqr, RZ Leo, V616 Mon, V1195 Oph, V529 Ori, WZ Sge, and V1017 Sgr) appear to be misclassified examples of other types of cataclysmic variables.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G. 16–19 June, 1986.     

The outbursts of dwarf novae

We present a numerical scheme for the evolution of an accretion disc through a dwarf nova outburst. We introduce a time-varying artificial viscosity into an existing smoothed particle hydrodynamics code optimized for two- and three-dimensional simulations of accretion discs. The technique gives rise to coherent outbursts and can easily be adapted to include a complete treatment of thermodynamics. We apply a two-dimensional isothermal scheme to the system SS Cygni, and present a wide range of observationally testable results.     

A theory of galactic mass and rotation curves

The goal of this paper is to account for the complete observed rotation curves of disk galaxies without dark matter. To attain that goal, use is made of a conservation law from stability theory of linear waves, leading to a vector-based theory of gravitation. In the theory, galactic centers are sites of strong gravitational fields. The new theory predicts extra matter at the center of disk galaxies, which is well-known to be consistent with intergalactic dynamics. For given disk radiusr ₀ and edge tangential speedv, the greater the deviation of a rotation curve from linear (solid disk rotation), the greater the mass of the galaxy as a multiple of Newtonian massr ₀v²/G, up to a factor of about 1000. In an approximate calculation it turns out that disk density (r) (in kg m^–2) is proportional to 1/r for typical rotation curves. Rotation is characterized by two constants which in turn are determined by the edge speed and mass distribution. Not just any curve shape can be so obtained; in fact, the theoretically possible curves correspond to observed curves.     

A catalogue and analysis of local galaxy ages and metallicities

We have assembled a catalogue of relative ages, metallicities and abundance ratios for about 150 local galaxies in field, group and cluster environments. The galaxies span morphological types from cD and ellipticals, to late-type spirals. Ages and metallicities were estimated from high-quality published spectral line indices using Worthey & Ottaviani (1997) single stellar population evolutionary models.
The identification of galaxy age as a fourth parameter in the fundamental plane ( Forbes, Ponman & Brown 1998 ) is confirmed by our larger sample of ages. We investigate trends between age and metallicity, and with other physical parameters of the galaxies, such as ellipticity, luminosity and kinematic anisotropy. We demonstrate the existence of a galaxy age–metallicity relation similar to that seen for local galactic disc stars, whereby young galaxies have high metallicity, while old galaxies span a large range in metallicities.
We also investigate the influence of environment and morphology on the galaxy age and metallicity, especially the predictions made by semi-analytic hierarchical clustering models (HCM). We confirm that non-cluster ellipticals are indeed younger on average than cluster ellipticals as predicted by the HCM models. However we also find a trend for the more luminous galaxies to have a higher [Mg/Fe] ratio than the lower luminosity galaxies, which is opposite to the expectation from HCM models.