SN 1987A has illuminated a great diversity of astrophysical processes – from neutrino emission during core collapse to the structure of the interstellar medium on a scale of hundreds of parsecs. Here I cover the evolution of SN 1987A from the outside in; the topics are interstellar light echoes, circumstellar light echoes, circumstellar shock waves, late emission and structure of the ejecta, and the effects of a central neutron star.

Type IIn supernovae have bright optical emission and high bolometric luminosities. Due to their high mass loss, their are expected to have dense circumstellar interaction, thus produce bright radio and X-ray emission. We aim to carry out systematic study to understand their circumstellar interaction, mass loss properties. Here, I provide specific examples of two Type IIn supernovae, 2006jd and 2010jl.

Supernovae of Type IIn (narrow line) appear to be explosions that had strong mass loss before the event, so that the optical luminosity is powered by the circumstellar interaction. If the mass loss region has an optical depth >c/vs, where vs is the shock velocity, the shock breakout occurs in the mass loss region and a significant fraction of the explosion energy can be radiated. The emission from the superluminous SN 2006gy and the normal luminosity SN 2011ht can plausibly be attributed to shock breakout in a wind, with SN 2011ht being a low energy event. Superluminous supernovae of Type I may derive their luminosity from interaction with a mass loss region of limited extent. However, the distinctive temperature increase to maximum luminosity has not been clearly observed in Type I events. Suggested mechanisms for the strong mass loss include pulsational pair instability, gravity-waves generated by instabilities in late burning phases, and binary effects.

The magnetohydrodynamic (MHD) model for young pulsar wind nebulae (PWN) has been successful in reproducing many features of the nebulae. The model is characterized by a termination shock (TS) between the PWN and unshocked pulsar wind. Relativistic particles are injected at the TS and follow an advective flow to the outer boundary. However, toroidal structure of well studied young PWN like the Crab Nebula, 3C 58 and G21.5-0.9 is only present in the region close to the TS. In the outer parts of the nebulae, filamentary and loop-like structure is observed. Also, the radial variation of spectral index due to synchrotron losses is smoother than expected in the MHD flow model. We find that a pure diffusion model with energy independent diffusion and a transmitting boundary can reproduce the basic data on nebular size and spectral index variation for the Crab, 3C 58, and G21.5-0.9. Energy dependent diffusion is also discussed. Power law variations of the coefficient with energy are degenerate with variation in the input particle energy distribution index in the steady state case. Monte Carlo simulations of particle transport with both diffusion and advection for the Crab nebula and 3C 58 suggest a picture in which advection dominates the inner part of the PWN where toroidal structure is clearly present. Diffusion dominates the outer part of the PWN where filamentary and loop-like structure is observed. The source of the chaotic field is uncertain, but may be related to Rayleigh-Taylor instability at the outer boundary of young nebulae and/or the kink instability of the toroidal magnetic field.

Observations of core collapse supernovae and their progenitors generally support expectations of increasing mass loss with increasing initial mass. Mass loss rates are expected to decline at lower metallicity, and there are prospects for directly testing this for the red supergiant progenitors of Type IIP supernovae. However, there are indications that mass loss rates for high mass early type stars may be overestimated and that there are mass loss mechanisms that do not decline at lower metallicity. In this case, there may be supernova emission from strong circumstellar interaction even at low metallicity. Although there is evidence for dust formation in freely expanding ejecta of supernovae, the quantities are relatively small. Another promising site of dust formation is the circumstellar interaction region, but this should occur in only a fraction of supernovae.

The evolutionary phases in going from a Type Ia supernova explosion to a 1000-yr-old remnant are reviewed. The explosion sets up the density and composition structure of the ejecta and can have radiative effects on the surroundings. The early shock interactions may be observable at radio and X-ray wavelengths if the circumstellar density is sufficiently high. The later interaction with the interstellar medium is affected by the collisionless shock physics and hydrodynamic instabilities.

The association of a supernova with a gamma-ray burst (GRB 030329) implies a massive star progenitor, which is expected to have an environment formed by pre-burst stellar winds. Although some sources are consistent with the expected wind environment, many are not, being better fit by a uniform density environment. One possibility is that this is a shocked wind, close to the burst because of a high interstellar pressure and a low mass loss density. Alternatively, there is more than one kind of burst progenitor, some of which interact directly with the interstellar medium. Another proposed environment is a pulsar wind bubble that has expanded inside a supernova, which requires that the supernova precede the burst.

Young supernova remnants that contain pulsar wind nebulae provide diagnostics for both the inner part of the supernova and the interaction with the surrounding medium, providing an opportunity to relate these objects to supernova types. Among observed young nebulae, there is evidence for a range of supernova types, including Type IIP (Crab Nebula and SN 1054) and Type IIb/IIn/IIL (G292.0+1.8).

Planetary Nebulae (PNe) are formed by the interaction of the fast wind from a post-Asymptotic Giant Branch Star with the slow ambient wind from a previous epoch. If the two interacting winds have constant properties, the velocity of the PN shell tends towards a constant with time and the shape becomes self-similar. Additionally, if the velocity of the fast wind is much higher than the expansion velocity of the shell, the interior of the hot shocked bubble becomes isobaric. Using semi-analytical methods, complemented by hydrodynamic simulations, we have calculated the shapes of PNe in the self-similar stage (Dwarkadas et al. 1996). We have investigated the contribution of the ambient wind velocity to PN morphology, which has hitherto not received much attention since the work of Kahn & West (1985). We find that the nebular morphology is a consequence of the density contrast between pole and equator in the ambient medium, the steepness of the density profile and the velocity of the ambient wind; classification of PNe purely on the basis of the first two factors may be misleading. In particular, the ratio of ambient wind velocity to PN velocity is important in determining whether the nebula shows a bulge or a cusp at the equator. A high density contrast coupled with a low velocity for the external medium gives rise to extremely bipolar nebulae. For large density contrasts and a significant value of the slow wind velocity, the surface density maximum of the shell shifts away from the equator, giving rise to peanut-shaped structures with pronounced equatorial bulges. As long as the external wind velocity is small compared to the expansion velocity of the nebula, the PNe tend to be more bipolar, even with a moderate density contrast. If the PN velocity is close to that of the external wind, the shape is relatively spherical. However, inclusion of an asymmetric velocity profile in the slow wind, with the velocity increasing towards the pole, can lead to a bipolar nebula if the equatorial velocity is sufficiently low. Preliminary results with a slow wind velocity increasing towards the equator (as is found in calculations of common envelope evolution) show that the nebulae tend to be more oblate, which is not often observed in nature. Representative results for shapes of PNe using various values of the relevant parameters are presented.

Core collapse in very massive stars can lead to a central black hole that swallows the rest of the star and in less massive stars to a central neutron star and explosion. There is probably an intermediate mass range that gives an explosion and a central black hole; supernova remnants with no observable central object are candidates. The association of pulsars with Type II supernovae gives an estimate of the pulsar power to be expected in a supernova, but the uncertainty in the initial pulsar periods gives a wide range in possible powers. The relativistic wind bubble model for the Crab Nebula has steadily developed and there are now predictions regarding particle acceleration in the optical wisps. The bubble model with expansion into supernova gas can also be applied to other young pulsar nebulae.

Plausible environments for supernovae are the interstellar medium with constant density or a circumstellar medium built up by mass loss with ρ ∝ r−n Self-similar solutions for the interaction region between the expanding supernova gas and the ambient gas exist provided that the expanding gas has ρ ∝ r−n with n > 5. The circumstellar medium case is likely to be important for the early evolution of Type II supernovae because their progenitor stars are probably red supergiants. The radio and X-ray emission observed from extragalactic supernovae may be from this interaction region. The early self-similar solutions can also be applied to the young galactic remnants.

An extensive grid of nonequilibrium ionization models for the X-ray spectra of adiabatic supernova remnants (SNRs) is described. The models are compared to the SSS spectra of remnants in the LMC, the Tycho SNR, and SNR 1006. In Tycho, we show that the observed spectrum requires significantly enhanced abundances of Si and S, and that this conclusion is independent of the detailed ionization and thermal structure in the remnant. We find that the SSS spectrum of SNR 1006 can be fit reasonably by a thermal emission model with abundances of about one half solar. In this model, the weak line emission results from the very low ionization state in the remnant, and not because the X-ray emission is non-thermal. We argue that the failure to detect strong Fe line emission in young Type I SNRs poses a severe problem for models of Type I SN, which predict that most of the ejecta be iron. Finally, the results of UV observations of a star behind SNR 1006 are mentioned; these observations show that the remnant contains a large amount of rapidly moving, cold iron.

Recent developments in the theory of the light from supernovae indicate that while Type II supernovae probably involve the explosion of a massive star with an extended envelope, Type I supernovae may involve the total thermonuclear disruption of a white dwarf. The energy release in a Type II supernova is presumably related to the contraction of the core to a neutron star and pulsar formation is likely. The hypothesis that Type II supernovae leave pulsars while Type I supernovae do not leave compact remnants is shown to be consistent with the available information on X-ray sources containing neutron stars, young supernova remnants, and the distribution of pulsars in the galaxy. Some pulsars are probably formed in the explosion of a massive star that has lost its envelope. These events may not be accompanied by a bright supernova display.