Since the only direct information, on the physics of supernova explosions comes from spectrophotometry of their light curves, it is wortwhile to put considerable effort on understanding the properties of supernova atmospheres. Two problems appear, however, in doing so. First, the mean free path of a photon in the region where the Spectrum forms (the atmosphere) is an important fraction of the supernova size and the plane parallel approximation breaks down. Second, the roles of scattering and absorption in the formation of the continuum are not clearly determined.

The complications introduced by spherical geometry arise from the angular derivative terms in the transfer equation and from the high degree of anisotropy introduced by the geometry. The complications introduced by scattering arise from the presence of the mean intensity in the source term of the transfer equation. As an outcome, its numerical solution is time consuming, and classical simplifications are not possible due to the strong anisotropy of the radiation field. In hydrodynamical calculations it is better to calculate the moments of the radiation field, but the success of this method depends on the possibility of replacing the infinite set of differential equations by the equations of low order moments plus a closure relationship that keeps all the properties of the higher moments.

We use a semi–analytical model of supernova light curves that extends Arnett’s scheme [1,2] to include the effect of recombination of hydrogen, helium and heavy elements in the expanding ejecta. Introducing in the model the physical parameters of Sanduleak −69 202, the salient characteristics of the light curve of SN 1987 A are reasonably reproduced over 100 days.

Recent observations of the young supernova remnant Cas A (Fesen et al., 1987) suggest an exploding Wolf-Rayet (WR) star of WNL type as a progenitor of this object. The majority of the WR stars seems to originate from massive O-stars of M > 40 M⊙. According to current investigations (Schild and Maeder, 1984; Langer, 1987; cf. also: Langer, this volume) WNL stars rank among the most massive WR stars. Hence, it is possible to assume that the stellar progenitor of Cas A was indeed a very massive star.

As shown by Langer and El Eid (1986), (see also Woosley, 1986) a population I star of initially 100 M⊙ may loose enough mass during its evolution up to core He exhaustion to become a WN star of ∼ 45 M⊙, which then mainly consists of oxygen (more than 80%) synthesized during He burning.

Recent results of SMM on the galactic 511 keV annihilation radiation exhibit a constant flux during 4–5 years, in total disagreement with post 1980 balloon observations. However, all these results are compatible if one admits the existence of a variable point source near the Galactic Center of FP ∼ 10−3 ph cm−1 s−1 and a diffuse interstellar source of positrons: FD ∼ 1.5−1.8 10 ph cm−2 s−1 rad−1. Evaluations of 26Al and 56Co decays contributions have been given last year (2) and that of 44Ti decays more recently (3). We have studied the nature of the sources of the main e+ − emitting radioisotopes − SN and novae − and their galactic distributions using the observational data at 511 keV and at 1809 keV, the galactic angular distributions considered by Leising and Clayton (4) and the nucleosynthesis of the models of novae and SN of Woosley and his collaborators (5).

High energy cosmic ray spectrum has been known to have an interesting bump in the energy range 1014 − 1016 eV. Various models to explain the spectral break in this energy range have been so far proposed; which incorporate either a large-scale termination of galactic wind, shocks with greater age and spatial extent associated with hypothetical super-bubbles powered by multiple supernovae, intersection of two quantum-gravitational components, extra-galactic component, red-shift of big-bang remnant, or a proton component from pulsars. More recently, their possible origin in type-II supernovae with magnetic acceleration mechanism is proposed by considering direct observational results of chemical composition near the bump regime of cosmic ray spectrum.

Gamma-rays originating from radioactive decays of 56Ni and 56Co and hard X-rays due to Compton degradation of γ-rays have been predicted to emerge when the supernova becomes sufficiently thin. The X-ray detections by Ginga (Dotani et al. 1988) and Kvant (Sunyaev et al. 1988) and more recent report of γ-ray detections by SMM (Matz et al. 1988) were much earlier than the theoretical predictions. (See Itoh et al. 1987 and references therein.)

These observations would give important constraints on the distribution of the heavy elements and 56Co in the ejecta. We adopted the hydrodynamical model 11E1Y6 (Nomoto et al. 1988) and carried out Monte Carlo simulation for photon transfer. A step-like distribution of 56Co was assumed where the mass fraction of 56Co in the layers at Mr ≤ 4.6 M⊙, 4.6 − 6 M⊙, 6 − 8 M⊙, and 8 − 10 M⊙ are XCo = 0.0128, 0.0035, 0.0021, and 0.0011, respectively. Other heavy elements were distributed with mass fractions in proportion to 56Co.

The supernova 1987A in the Large Magellanic Cloud has provided a new opportunity to study the evolution of a young neutron star right after its birth. A proto-neutron star first cools down by emitting neutrinos that diffuse out of the interior within a minutes. After the neutron star becomes transparent to neutrinos, the neutron star core with > 1014 g cm−3 cools predominantly by Urca neutrino emission. However, the surface layers remain hot because it takes at least 100 years before the cooling waves from the central core reach the surface layers (Nomoto and Tsuruta 1981, 1986, 1987).

From the hot surface, thermal X-rays are emitted. The detection limit for X- rays from SN 1987A by the Ginga satellite is 3 ×1036 erg s−1 (Makino 1987; Tanaka 1987). If the thermal X-rays are to be observed by Ginga, the surface temperature should continue to be as high as Ts > 8 ×106 (R/10km)−1/2 K until the ejecta becomes transparent. The exact value of the initial surface temperature depends on various factors during the violent stages of explosion, cooling stages of the proto-neutron star through diffusive neutrinos, and possible re-infalling of the ejected material. Therefore, until the surface layers become thermally relaxed Ts may satisfy the above condition.

The X-ray spectrum observed by Ginga is characterized by a component below 10keV which decreases with increasing photon energy, and a component above 10keV which is nearly flat. This unusual X-ray spectrum may be understood as follows; X-rays below 10keV is likely to be due to thermal emission coming from the shock-heated ejecta, and X-rays above 10keV to be due to γ-ray degradation inside the ejecta. If thermal emission due to the collision of the ejecta with circumstellar matter (CSM) is responsible for X-rays below 10keV, the epoch of the collision can be estimated to be ∼ 0.2yr after the explosion if ∼ 0.5yr is the time when the X-ray flux at ∼ 10keV reaches its maximum. The X-ray light curve then requires the inner radius of CSM to be ∼ 1×1016cm for an expansion velocity, Vex ≃2×109cm s−1.

The Crab Nebula is the most noticeable object in our Galaxy, and the remnant of the famous Chinese guest star appeared in 1054AD, the best association between supernova remnants(SNR) and ancient guest stars. Before seventies, the Crab Nebula was considered as a special SNR with different morphology and physical features from that of most SNRs, Now more and more Crab-like SNRs have been detected(Weiler 1985). It is necessary to make a systematical investigation for the Crab-like SNRs, especially for those with central pulsars because they offer us more physical messages than others.

The two associations SNR and PSR, the Crab Nebula with PSR 0531+21 and the Vela SNR with PSR 0833-45, were confirmed at the end of sixties and still were the only two associations before eighties. Recent years, PSR 1509-58 in MSH 15-52 and PSR 0540-69 in a SNR of LMC(Seward & Harnden 1984, Seward etal. 1984) as well as PSR 1951+32 in CTB 80 (Clifton et al. 1987, Fruchter etal. 1987) were discovered. On the other hand, the X-ray emission of PSR 1055-52 and others were detected (Cheng & Helfand 1983, Helfand 1983). Recently, we searched for the X-ray emission of isolated pulsars over more than thirty fields in Einstein observation. By use of the same instrument calibrstions, the X-ray luminosities of ten isolated pulsars and their surrounding nebulae are obtained. Let Lx be the total X-ray luminosity of a pulsar and its nebula in the 0.2-4.0 kev band, and E be the rotating energy loss rate of the pulsar, the following statistical relation is obtained by linear regression and shown as the line in Fig. 1.

Due to the growing interest in the SN(supernovae) phenomenon in recent years, and to large amount of data which has been accumulating lately, there is now a need for a new publication in which to find all the essential data on SNe and their parentgalaxies. A revised 568 supernova catalogue has published by Barbon et al (1984).

The paper supplements 65 SNe, discovered since 1984 up to update, and some statistical studies were completed.

The first two comprehensive lists of SNe were published by Zwicky(1958, 1965) and included the 54 and 111 objects respectively reported up to 1956 and 1962. A more complete list was issued by Zwicky(1964), 154 SNe is inclused.

We observed the Cygnus Loop with Gas Scintillation Proportional Counter (GSPC) on board Tenma satellite. GSPC has an energy resolution two times better than that of a proportional counter (PC). Fig. 1 shows the spectrum with the crosses being the pulse height data with ± 1σ statistics. Superposed upon the data point is the best fit model spectra folded through the detector response.

Zwicky started extragalactic supernovae patrol using 10 inch Schmidt camera about fifty years ago. After that the research of supernovae was accelerated, because the wide view of the Schmidt camera made it possible to watch large field of the sky. The key technology of the Schmidt camera was its sophisticated optical system.

Anticipated next supernova in our Galaxy may be undetectable by the optical instrument due to the Galactic extinction. However, supernovae are now known to be intense radio sources after a year or so of the explosion. Even if the positions are beyond the Galactic center, the radio supernova could be observed using middle size radio telescope.

The discussions during the colloquium clearly pointed to the recent rapid progress in applying the atmospheric models to the detailed diagnostics of stellar evolution.

The high–quality spectroscopic data now available enable us to evaluate the abundances of scarce elements and isotopes in the classical stellar atmospheres. Many of them are found to be useful to sound the mixing and the gravity settling phenomena in the stellar interior. Extensive contributions were presented about the former process in the AGB stars, and about the latter process in the Li–defficient F stars.

The evolutionary interactions between the stellar interior and the atmosphere become distinct when the mass-loss processes set in. It was pointed out that high–rate mass loss can influence the internal evolution and mixing on one side, and that on the other side the mixing (dredging–up) can change the abundances of heavy elements in the atmosphere and further modulate the mass–loss rate. Many speakers presented ample of observational data from UV to mm–wave range indicating occurences of substantial mass loss from various kinds of stars. Self consistent models with spherical geometry were proposed for stellar winds which are driven by the radiation pressure acting on ions or dust grains. This involves comprehensive calculation related to the molecular chemistry and the grain physics. So far as the flow is stationary and spherically symmetric, the escape velocity and the mass–loss rate determine the density structure of the wind in radiative equilibrium.

In the Opening Remarks Dr. Kudritzki asked what tricks were used in calculating stellar structure. Though many fine models and discussions have been presented, answer has not been given yet to this question. The theory of stellar structure consists of two very much different kinds of building blocks. One is the local physics such as equation of state, opacity, nuclear reaction rate, and so on. They are determined only locally when the values of temperature and density at a point are given, i.e., they are irrelevant to the conditions whether they are considered in the stellar interior or not. Another is the physics of self-gravitating systems in which the global spatial structures are discussed. Characteristics of astrophysics are often said to lie in the fact that it covers much wider parameter ranges than in laboratories. This, however, grasps only one side of the problem, i.e., only local physics. Those which are not encountered in laboratory physics lie mainly in the global physics. It shows characteristics out of common sense; examples are negative specific heat and associated gravothermal catastrophe which are related with the gravitational contraction of the stars, formation of core halo structures which is observed not only in red giant stars but also many celestial objects, and tendencies dividing a system into two sub-systems one with high energy and/or high entropy and the other with low energy in the deep potential well and/or low entropy as seen in supernova explosion of type II and formation of jet in various objects. They behave contrary to the general trend, i.e., against equipartition and thermal equilibration.