We present a study of the morphology of the ejecta in Supernova 1987A based on images and spectra from the Hubble Space Telescope (HST) as well as integral field spectroscopy from VLT/SINFONI. The HST observations were obtained between 1994 and 2011 and primarily probe the outer H-rich zones of the ejecta. The SINFONI observations were obtained in 2005 and 2011 and instead probe the [Si i]+[Fe ii] emission from the inner regions. We find a strong temporal evolution of the morphology in the HST images, from a roughly elliptical shape before ∼5000 days, to a more irregular, edge-brightened morphology with a "hole" in the middle thereafter. This transition is a natural consequence of the change in the dominant energy source powering the ejecta, from radioactive decay before ∼5000 days to X-ray input from the circumstellar interaction thereafter. The [Si i]+[Fe ii] images display a more uniform morphology, which may be due to a remaining significant contribution from radioactivity in the inner ejecta and the higher abundance of these elements in the core. Both the Hα and the [Si i]+[Fe ii] line profiles show that the ejecta are distributed fairly close to the plane of the inner circumstellar ring, which is assumed to define the rotational axis of the progenitor star. The Hα emission extends to higher velocities than [Si i]+[Fe ii], as expected from theoretical models. There is no clear symmetry axis for all the emission. Instead, we find that the emission is concentrated to clumps and that the emission is distributed somewhat closer to the ring in the north than in the south. This north-south asymmetry may be partially explained by dust absorption. We compare our results with explosion models and find some qualitative agreement, but note that the observations show a higher degree of large-scale asymmetry.

We present observations with VLT and HST of the broad emission lines from the inner ejecta and reverse shock of SN 1987A from 1999 Feb. until 2012 Jan. (days 4381 -9100 after explosion). We detect broad lines from Hα, Hβ, Mg I], Na I, [O I], [Ca II] and a feature at ∼ 9220Å. We identify the latter line with Mg II λλ 9218, 9244, which is most likely pumped by Lyα fluorescence. Hα, and Hβ both have a centrally peaked component, extending to ∼ 4500 km s −1 and a very broad component extending to 11, 000 km s −1 , while the other lines have only the central component. The low velocity component comes from unshocked ejecta, heated mainly by X-rays from the circumstellar environment, whereas the broad component comes from faster ejecta passing through the reverse shock, created by the collision with the circumstellar ring. The flux in Hα from the reverse shock has increased by a factor of 4 − 6 from 2000 to 2007. After that there is a tendency of flattening of the light curve, similar to what may be seen in soft X-rays and in the optical lines from the shocked ring. The core component seen in Hα, [Ca II] and Mg II has experienced a similar increase, which is consistent with that found from HST photometry. The ring-like morphology of the ejecta is explained as a result of the X-ray illumination, depositing energy outside of the core of the ejecta. The energy deposition of the external X-rays is calculated using explosion models for SN 1987A and we predict that the outer parts of the unshocked ejecta will continue to brighten because of this. We finally discuss evidence for dust in the ejecta from line asymmetries.

We discuss high resolution VLT/UVES observations (FWHM ∼ 6 km s −1 ) from October 2002 (day ∼5700 past explosion) of the shock interaction of SN 1987A and its circumstellar ring. A large number of narrow emission lines from the unshocked ring, with ion stages from neutral up to Ne V and Fe VII, have been identified. A nebular analysis of the narrow lines from the unshocked gas indicates gas densities of (∼1.5−5.0) × 10 3 cm −3 and temperatures of ∼6.5 × 10 3 −2.4 × 10 4 K. This is consistent with the thermal widths of the lines. From the shocked component we observe a large range of ionization stages from neutral lines to [Fe XIV]. From a nebular analysis we find that the density in the low ionization region is 4 × 10 6 −10 7 cm can be seen probably arising from a small fraction of shocked high density clumps. We discuss these observations in the context of radiative shock models, which are qualitatively consistent with the observations. A fraction of the high ionization lines may originate in gas which has yet not had time to cool, explaining the difference in width between the low and high ionization lines. The maximum shock velocities seen in the optical lines are ∼510 km s −1 . We expect the maximum width of especially the low ionization lines to increase with time.

Context. Observing the inner ejecta of a supernova is possible only in a handful of nearby supernova remnants. The core-collapse explosion mechanism has been extensively explored in recent models and predict large asymmetries. SN 1987A is the first modern stellar explosion that has been continuously observed from its beginning to the supernova remnant phase. Twenty years after the explosion, we are now able to observe the three-dimensional spatially resolved inner ejecta of this supernova. Aims. Detailed mapping of newly synthesised material and its radioactive decay daughter products sheds light on the explosion mechanism. This may reveal the geometry of the explosion and its connection to the equatorial ring and the outer rings around SN 1987A. Methods. We have used integral field spectroscopy to image the supernova ejecta and the equatorial ring in the emission lines of [Si I] + [Fe II] (λ1.64 μm) and He I (λ2.058 μm). The spectral information can be mapped into a radial velocity image revealing the expansion of the ejecta both as projected onto the sky and perpendicular to the sky plane. Results. The inner ejecta are spatially resolved in a North-South direction and are clearly asymmetric. Like the ring emission, the northern parts of the ejecta are blueshifted, while the material projected to the South of the supernova centre is moving away from us. We argue that the bulk of the ejecta is situated in the same plane as defined by the equatorial ring and does not form a bipolar structure as has been suggested. The exact shape of the ejecta is modelled and we find that an elongated triaxial ellipsoid fits the observations best. The velocity measured in the [Si I] + [Fe II] line corresponds to ∼3000 km s −1 and is the same as the width of the IR [Fe II] line profiles during the first years. From our spectral analyses of the ejecta spectrum we find that most of the He I, [Si I] and [Fe I-II] emission originates in the core material which has undergone explosive nucleosynthesis. The He I emission may be the result of α-rich freeze-out if the positron energy is deposited locally. Conclusions. Our observations clearly indicate a non-symmetric explosion mechanism for SN 1987A. The elongation and velocity asymmetries point towards a large-scale spatial non-spherical distribution as predicted in recent explosion models. The orientation of the ejecta in the plane of the equatorial ring argues against a jet-induced explosion through the poles due to stellar rotation.

Context. SN 1987A in the Large Magellanic Cloud is close enough for a study of the very late time evolution of a supernova and its transition to a supernova remnant. Nearly two decades after explosion we are witnessing the supernova shock wave engaging the inner circumstellar ring, which had been fluorescing since being ionised by the soft X-ray flash from shock breakout. Aims. We follow the interaction of the supernova shock with the ring material. The spatially resolved information provides us with insight into the individual shock regions around the ring. Methods. Near-infrared integral field spectroscopy observations with SINFONI/VLT of the SN-ring interaction is presented. SINFONI's adaptive optics supported integral field spectrograph spatially resolves the ring and the data thus we obtain a better spatial understanding of the spectrum in different regions of the object. Results. With a dynamical map of the interacting ring we determine parameters for its geometry. Since most of the IR emission lines originate behind the shock front we obtain an indication of the radial velocity of the shocked material after deconvolving the geometry. The ring geometry is consistent with a circle and we also derive a new, independent measurement of the systemic ring, and presumably also supernova, velocity. We find from the spatial distributions of the flux in the different emission lines the degree of cooling in the shocked material and follows the increases observed in the radio and X-rays. Emission from the ejecta is detected only in the strongest [Fe ii] lines.