Observations at 408 and 1420 MHz are reported which show a large (1.7 degree diameter) faint shell of nonthermal emission partially surrounding PSR1930+22. This may be the SNR associated with the pulsar, whose spin-down age is only 40000 years.

Pulsar-like emission has been detected from the flat-spectrum component of the galactic radio source CTB80. The consequences for the source are discussed.

While the number of galactic supernova remnants (SNRs) now known is fairly large (>150), the subset among these that are known to resemble the Crab Nebula is still distressingly small, about 15 or so (Green, 1984). Thus any object that can be unambiguously included in this exclusive club forms a valuable addition to our knowledge of this class. We report here observations of a newly recognised nonthermal galactic object, G18.94-l.06, having all the hallmarks of the classical shell-type SNRs, while also appearing to have a filled-centre component located inside the shell. Among the known Crab-like remnants, about one third show this dual nature (Green, 1984). This diagnosis of G18.94-1.06 is supported mainly by the variations in spectral index α (Sν∝ να) across the source, as seen between the two observation frequencies, 408 MHz and 5.0 GHz.

At the CSIRO Division of Radiophysics we are currently engaged in a program to map polarization in SNRs at 8.4 GHz. These results are compared with earlier Parkes 5 GHz maps to deduce the direction of magnetic field, Faraday rotation and depolarization.

Radio sources in the field of the extended SNR OA184 (G166.2+2.5) have been studied to determine the excess rotation measure (RM) arising from the SNR. Of a total of 32 radio sources observed with the VLA in the C configuration, eight are found to be polarized above 7σ The sources seen through the SNR show significantly high RM in comparison to background sources. The excess RM due to the Faraday active plasma in the SNR is estimated to be 150±20 rad m−2, which corresponds to . The sign of RMs of the sources within an area of about 2°×2° centred on the SNR shows a systematic longitudinal polarity change on either side of l ≈ 166°.2. Although a larger sample is needed to justify this, we tentatively interpret this “flip” as due to the reversal of an irregular component of the galactic magnetic field on a scale of order 100 pc.

We argue that the majority of radio supernova remnants have a three-dimensional distribution of emissivity which is barrel shaped, with little emission from the end-caps. We examine some mechanisms which could produce this distribution.

Infrared observations of supernova remnants obtained with the Infrared Astronomical Satellite provide new insights into the dynamics and energetics of the remnants, and into their interaction with the ambient interstellar medium. In most remnants the infrared emission arises from dust that is collisionally heated by the X-ray emitting gas. The infrared observations can therefore be used as a diagnostic for the physical conditions of the shocked gas. In particular, it is shown that all the prominent X-ray remnants in the Galaxy and in the LMC cool mainly by dust grain collisions instead of atomic processes.

Presented here are preliminary results from a survey of supernova remnants (SNRs) in the data base collected by the Infrared Astronomical Satellite (IRAS). About one-third of the known galactic SNRs are visible in the IRAS data. Confusion with other sources in the galactic plane prohibits the detection of many remnants. The objects that are detected have similar spectral characteristics and temperatures, except that the three youngest remnants known, Tycho, Kepler, and Cassiopeia A, are distinctly warmer.

IRAS additional observations show that luminous (104−105 L⊙) far-IR sources are associated with the Large Magellanic Cloud (LMC) supernova remnants N63A, N49, N49B, and N186D. Comparison of the IRAS and X-ray data shows that a substantial fraction of the IR emission from three of the SNRs can be accounted for by collisionally heated dust. The ratio of dust-grain cooling to total atomic cooling is ~10 in X-ray emitting gas (T~106 K). We show why dust cooling does not dominate, but probably speeds SNR evolution in an inhomogeneous interstellar medium.

The possibilities for observing infrared emission from shock-heated dust in SNRs with the future Infrared Space Observatory (ISO) are illustrated with calculations of the ISOPHOT-P and ISOPHOT-C flux densities and integration times for radiation from six selected SNRs in eight wavelength bands between 4µm and 180µm.

Spectra of several galactic and LMC supernova remnants have been obtained at R ~ 1500 in the 1−2.5 µm region with the cooled grating/array spectrometer, IRSPEC, on the ESO 3.6m telescope. The brightest lines observed are from [FeII]. In RCW 103, which exhibits the highest surface brightness, H (Brγ at 2.17µm) and H2 (1−0 S(1) at 2.12µm) lines have also been detected. A good correlation is found between [FeII] (1.64µm) and Hβ implying similar ionization structures and Fe abundances in a wide variety of remnants. The actual [FeII](1.64µm)/Hβ ratio of ~0.2 also implies a high depletion factor (>0.9) for Fe. Electron densities, extinctions and [FeII] luminosities derived from these data are presented and discussed and attention drawn to a potentially interesting discrepancy between H(Brγ) and Hβ fluxes.

We present infrared (IR) spectroscopy and imaging of the supernova remnant IC443. [FeII] 1.644µm, Brackett γ and H2 1-0 S(l) were detected. The most striking feature of the spectra is the high [FeII] 1.644µm/Brackett γ ratio, which is typically ~30. We argue that this ratio is due to shock excitation. Two 5’×3’ maps of the remnant in the 1.644µm [FeII] line are used to study the line excitation. The IR [FeII] line is a sensitive probe for regions of shocked gas which is especially useful where the extinction is high, or the shocks are too slow to excite optical lines.

Observations are presented of shocked line emission from H2, CO and HCO+ molecules in the SNR IC 443. IC 443 is the most luminous galactic H2 emission line source yet discovered. The implications for physical processes in shocked molecular gas are discussed.

High resolution observations at radio, infrared, optical and X-ray wavelengths have been made (Mufson et al. 1986). The infrared spectrum determined from the IRAS observations has been fitted with models which include shock heated dust, infrared line emission, and radiatively heated dust emission. Numerical simulations of a supernova expanding into a uniform medium, which describe the X-ray and large scale radio emission, are presented.

This paper presents images of two areas of the supernova remnant IC443 showing emission from the [Fe X] 6374Å red coronal line taken with an emission line differential imaging camera. The areas are in the vicinity of strong soft X-ray emission as observed with the Einstein Observatory. The [Fe X] emission is patchy on the scale of seconds of arc. For the highest emission regions we find an electron density of approximately 100 cm−3 and gas pressures of 108cm−3K. No correlation is found between the X-ray and [Fe X] knots, and the results support a clumpy, multi-temperature region where the [Fe X] knots are balanced between collapse and evaporation.

We present the first results of an observational program of SNRs in the coronal lines of [FeX] and [FeXIV] using the Fabry-Perot spectrophotometer of the Observatoire de Marseille. These support previously published brightnesses.

We present deep Hα and [O III] images and echelle spectra of non-radiative shocks in the NE Cygnus Loop. The contrast between the smooth Hα structure and the clumpier [O III] indicates that portions of the sheet-like front are beginning to go radiative. The column depth through the shock seems to be ≼ 1017.5 cm−2 for the entire region – a remarkable constraint for such a large structure.

An older remnant will be defined as one in which radiative cooling occurs somewhere and has swept up enough mass for the details of the explosion to be less important than the state of the interstellar medium in which the explosion occurred. Without discussing any particular remnant in detail, I will consider how large and small scale density variations in the ambient medium affect the appearance and energetics of such remnants. Finally I will show that radiative instabilities can modify the emission spectrum of radiative shocks in such a way that a naive interpretation of these spectra can be very misleading.

We present an analytic kinematic model for the evolution of a supernova remnant beginning with the Sedov-Taylor adiabatic stage and continuing through the radiative stage. Using this model, we obtain the luminosity of the radiative shock and the hot interior.

The stability of a radiative shock subject to nonequilibrium cooling is Investigated. It is found that high velocity shocks (> 140 km/s) are subject to oscillational and condensational instabilities.