The disturbance of components and system parameters by mass transfer during and at the end of core hydrogen burning, as well as at the onset of core helium burning is reviewed. Emphasis is given to the influence of the evolution of the gainer and to the variation of the chemical composition of the surface.

The distribution of the WR cluster members is interpreted in terms of their association with the galactic spiral-arm pattern. It is suggested that in a limited volume the number fraction of WR binaries is influenced more by magnetic field properties of the spiral arms, than by function of the galactocentric distance.

The current understanding of the common envelope binary phase of evolution is presented. The results obtained from the detailed computations of the hydrodynamical evolution of this phase demonstrate that the deposition of energy by the double core via frictional processes is sufficiently rapid to drive a mass outflow, primarily in the equatorial plane of the binary system. Specifically, recent calculations suggest that large amounts of mass and angular momentum can be lost from the binary system in a such a phase. Since the time scale for mass loss at the final phase of evolution is much shorter than the orbital decay time scale of the companion, the tranformation of binary systems from long orbital periods (> month) to short orbital periods (< day) is likely. The energy efficiency factor for the process is estimated to lie in the range between 0.3 and 0.6.

Millisecond pulsars are intrinsically interesting because they illustrate some of the most extreme physical conditions to be found anywhere in the Universe, and because their evolution exhibits several stages of great drama. It had been widely believed for several years that spin-up of an old neutron star by accretion from a close stellar companion explained their fast rotation, but the absence of companions in several cases cast doubt on that picture. This spring a millisecond pulsar in a close binary was discovered in which the companion appears to be evaporating, thus reconciling the existence of lone millisecond pulsars with the standard picture. Ongoing observations of this new system, and complementary calculations, promise to answer many of the questions remaining about this dramatic phase in stellar evolution.

The minimum period of hydrogen rich cataclysmic binaries at about 80 minutes is due to evolution driven by gravitational radiation. The nature of the gap between 2 and 3 hour periods is less clear. Magnetic braking may be responsible, but this would be in contradiction with the hibernating nova scenario. It is interesting that contact binaries of W UMa type are subject to little or no magnetic braking.

The AM Her period spike is due to the resumption of mass transfer after evolving through the period gap. This implies that (i) at the spike period all secondary stars are the same (ii) most AM Her white dwarfs have a unique mass ⋍0.6 — 0.7M⊙ (iii) nova explosions on magnetic white dwarfs remove exactly the mass accreted between outbursts (iv) the newly discovered AM Her system at 127min has a mass ⋍1.3 — 1.4M⊙ (V) the maximum magnetic field for most AM Her’s is ≤ 4 x 107 G.

A new progenitor model of Type la supernovae (SNe Ia) is proposed. The model consists of a carbon-oxygen white dwarf (0.8-1.2 M⊙) and a low-mass red giant star (0.8-1.5 M⊙) with a helium core (0.2-0.4 M⊙). When a red giant fills its inner critical Roche lobe and its mass transfer rate exceeds a critical value, a common envelope state is realized. Then the mass accretion rate onto the white dwarf, i.e., the mass transfer rate is tuned up to be Ṁ= 8.5 × 10−7 (MWD/M⊙-0.52) M⊙ yr−1, where MWD is the mass of the white dwarf. This rate is high enough to suppress the hydrogen shell flashes, but too low for carbon to be ignited off-center. When the carbon-oxygen core mass grows to the Chandrasekhar limit during the common envelope phase, a Type la supernova explosion is expected to occur.

In one sense our subject is an old one, dating back more than two centuries to the work of John Michell on statistics of visual star pairs. In another sense, it is both young and rapidly growing. The first meeting devoted exclusively to binary systems took place in 1966 in Uccle, Belgium, followed by the first IAU Joint Discussion on the subject in 1967 and IAU Colloquia 6 and 18 in 1969 and 1972. From this average of less that one meeting with published proceedings per year, our gatherings have proliferated to about five per year in the mid 80’s. I am inclined to suspect that the topic of formation and evolution of binary stars is now too broad to fit into any one meeting, room, day, or mind.

The Type II supernova SN1987A which occurred in the LMC is the brightest and most completely observed supernova ever recorded. Objective prism and UBV observations were made of the blue supergiant progenitor Sanduleak −69°202 and indicate that the visual absorption lies in the range 0.4<AV<0.6. Furthermore, the distance to the LMC is known in absolute units with a precision of about ± 15% (m-M = 18.45, Feast 1988) which combined with the above data and subseguent photometric observations permits detailed comparison with theory.

Within 107 minutes of the Kamiokande 1MB neutrino event the region of the supernova was being observed by Albert Jones, although it was not until 0.8 days after the event that the supernova was officially discovered by Shelton. The first photoelectric observation was made at 1.1 days, by William Allen (1988) a New Zealand amateur. Other observations made during the first two days, have been conveniently tabulated by Arnett (1988). During this time the supernova steadily brightened in V, although theory predicts that it was rapidly fading bolometrically and cooling, after the intense heating that occurred when the shock wave reached the stellar surface about 3 hours after core collapse.

Results of observations carried out during the past year and a half after the explosion of SN1987A (February 23 1987), show strong evidence for asymmetry in the expanding shell. The departure from spherical symmetry in SN1987A has important implications for further detailed modeling of supernovae explosions, light curves and spectra.

Gamma-ray lines from the decay of 56Co in the SN1987A remnant have been detected by satellite and balloon experiments. The observations directly confirm the basic theoretical tenet that 56Ni was explosively synthesized in the aftermath of core collapse of the blue super giant Sanduleak – 69 202. The flux level of the 56Co lines at 847 keV and 1238 keV, from the Gamma-Ray Spectometer (GRS) on the SMM satellite, is consistent with a constant level from 1987 August through 1988 May. The early appearence of the γ-ray lines and the continuum reported by the Ginga and Mir-Kvant satellite experiments require mixing, or clumping of a few percent of the newly synthesized 56Ni in the expanding envelope. Results from balloon experiments, which are in the preliminary stage of analysis, do not give clear evidence for γ-ray line shifts from rest energies with a limit ΔE/E < 0.002, nor is there definitive evidence, at this time, of line splitting, but γ-ray line widths are clearly wider than instrument resolution at ΔE/E < 0.02. The continuum (50-500) keV/line ratio has stayed approximately constant at 8 from 1987 August to 1988 May indicating the origin of the continuum from Compton down-scattering of deeper lying 56Co and lines from 56Co at smaller γ-ray optical depths. Future balloon flights of the most sensitive high-resolution spectrometers, planned for 1988 November and 1989 April, are expected to be able to detect weaker γ-ray lines at a flux level of ~ 10-4 γ cm-2 s−1 for the 847 keV line. SN1987A was just close enough to the Earth to confirm theory with existing instruments. In this report we review only γ-ray line results, since the continuum observations have been reviewed by Professor Trümper in this session.

Model calculations for the interpretations of the CO bands in the IR are discussed. Spherical symmetry is assumed. Profiles of the physical quantities (i.e. temperature, mass, electron density, abundances, etc.) are given by NLTE models which allow for the representation of observed spectra of supernova 1987A in the optical and near infrared. C and O have to be chosen overabundant by a factor of 25 in the helium-rich layers, or a clumpy density distribution structure of a corresponding factor relative to the mean local value is needed. However, the comparison between the observed forbidden OI line at about 6300 A favours the first interpretation. A factor of about 3 has to be taken into account as uncertainty for the overabundance because of the assumptions of the background model. This implies evidence for strong mixing of the helium rich region with more central layers during the stellar evolution and/or the explosion.

Adiabatic supernova explosions of polytropic stars are investigated by a three dimensional Smoothed Particle Hydrodynamics. The evolution of thermal point explosions is almost spherically symmetric in a global sense, but they are found to be unstable against Rayleigh-Taylor instabilities. The typical unstable wavelength, which grows in the nonlinear stage, is comparable to the thickness of the spherical shell. As a result, we find a porous density structure on the expanding shell. These results suggest the dumpiness of the ejecta of supernova explosions. The accompanying mixing motion in the expanding shell can explain the rapidly rising light curve of SN1987A. Because it may mix up the energy source 56Ni towards the outer layers of supernovae.

The synthetic line profiles presented here are the result of a series of models :

• - Woosley's (1988) calculation of the stellar explosion yield the luminosity, the density and the velocity structure of the expanding SN as a function of time (Woosley's model 10HM was used)

• - subsequent Monte Carlo simulations of the radiation transport in the expanding photosphere are based on the atmosphere structure given by the model above for a given time. The calculations take into account tens of thousands of lines and yield the line blanketed continuum flux and the temperature structure.

• - The previous two models specify the physical condition of the expanding shell. With a third model the NLTE populations of 10 H and 12 He levels are determined and the emergent hydrogen lines profiles are obtained. The method of solving the NLTE problem is described by Wessolowski et al. (1988) and references therein.

The X-ray emission from the interaction of the ejecta with circumstellar matter (CSM) for SN1987A is investigated. The electron and the ion temperatures seem to be in non-equilibrium in the early phase of a SN remnant. We have studied the two-temperature model in the early phase of SNR and discuss the X-ray emission from SN1987A and its CSM.

The observations of the narrow UV and optical emission lines from SN 1987A are modelled as reprocessed radiation in a shell around the supernova, heated and ionized by the soft X-ray and EUV radiation at the shock breakout. Constraints on the early soft X-ray burst are discussed, as well as the physical conditions and abundances in the shell.

Observations of the neutrino burst from Supernova 1987A by water Cherenkov detectors (KAMIOKANDE II, IMB) and liquid scintillator detectors (Baksan, Mont Blanc) are reviewed. It is shown that neutrino signal from SN 1987A was observed. There are 24 events in three detectors (KAMIOKANDE II, IMB, Baksan) recorded at 7:35 UT. The average properties of the signal (effective neutrino temperature, total energy of neutrino emission, burst duration) are consistent with the general theoretical description of supernova explosions. Special attention is concentrated on individual characteristics of the signals detected and the available discrepancies of the model estimates. Time profile of the neutrino burst, estimates of effective neutrino temperatures and total neutrino energies, angular distributions of the events are discussed. These properties point out, probably, a more compound picture of the phenomenon. The more detail analysis of the experimental data is needed and all possibilities must be at least considered. Based upon the Baksan observations, an upper limit of 0.35 core collapse in the Galaxy per year (90% C.L.) is shown.

Interstellar dust is described as consisting predominantly (by mass) of tenth micron (mean size) silicate core-organic refractory mantle particles which have evolved over galactic time scales of the order of 5 billion years. These particles were incorporated into comets and asteroids in the presolar nebula 4.5 billion years ago. The fragmentation of those primitive bodies gives rise to solar system debris which shows up as comet dust, zodiacal light, IDP’s and meteorites. The chemical and morphological structure of comet dust is derived here as fluffy aggregates of interstellar dust. The chemical and morphological structure of the chondritic porous IDP’S are then derived from comet dust which has evolved in the solar system. Zodiacal light particles are interpreted as various stages between comet dust and IDP’s. Meteorites appear to be a side branch in the evolution from interstellar to solar system particles.

This paper describes how the families of minor planets were discovered and how minor planets are classified into families and shows several evidences that at least some families were originated by collisions of minor planets. In fact for major families there are much more fainter minor planets than in other regions and when the families were discovered by Hirayama in 1918 only one sixth of the total numbered minor planets belonged to families whereas now more than one third of them belong to the families. It is also emphasized that the classification into the families is theory dependent and that any theory available now is not accurate enough to derive stable quantities for the families to study their origins as the families are usually bounded partly by mean motion and/or secular motion commensurability regions in the phase space.