We present and discuss new visual wavelength-range observations of the inner regions of the supernova remnant SNR 0540-69.3 that is located in the Large Magellanic Cloud (LMC). These observations provide us with more spatial and spectral information
than were previously available for this object. We use these data to create a detailed three-dimensional model of the remnant, assuming linear expansion of the ejecta. With the observations and the model we study the general three-dimensional structure of the remnant, and the influence of an active region in the remnant - a blob - that we address in previous papers. We used the fibre-fed integral-field spectrograph VIMOS at the Very Large Telescope of the European Southern Observatory. The observations provide us with three-dimensional data in [OIII]5007 and [SII]6717,6731 at an 0.33x0.33 spatial sampling and a velocity resolution of about 35 km/s. We decomposed the two, partially overlapping, sulphur lines and used them to calculate electron densities across the remnant at high signal-to-noise ratio. Our analysis reveals a structure that stretches from the position of the blob, and into the plane of the sky at a position angle of about 60 degrees. We speculate that the pulsar is positioned along this activity axis, where it has a velocity along the line of sight of a few hundred km/s. The blob is most likely a region of shock activity, as it is mainly bright in [SII]; future observations of [OII]3729 would be useful to test whether the S/O abundance ratio is higher than average for that location in the remnant. The striking resemblance in X-rays between the pulsar wind nebula (PWN) of SNR 0540-69.3 and the Crab, in combination with our findings in this paper, suggests that the symmetry axis is part of a torus in the PWN. (abridged)
Strong mass loss off stars at the tip of the asymptotic giant branch (AGB) profoundly affects properties of these stars and their surroundings, including the subsequent planetary nebula (PN) stage. With this study we wanted to determine physical prop
erties of mass loss by studying weakly emitting halos, focusing on objects in the galactic disk. Halos surround the, up to several thousand times, brighter central regions of PNe. Young halos, specifically, still contain information of the preceeding final mass loss stage on the AGB. In the observations we used the method of integral field spectroscopy with the PMAS instrument. This is the first committed study of halos of PNe that uses this technique. We improved our data analysis by a number of steps. In a study of the influence of scattered light we found that a moderate fraction of intensities in the inner halo originate in adjacent regions. As we combine line intensities of distant wavelengths, and because radial intensity gradients are steep, we corrected for effects of differential atmospheric refraction. In order to increase the signal-to-noise of weak emission lines we introduced a dedicated method to bin spectra of individual spatial elements. We also developed a general technique to subtract telluric lines - without using separate sky exposures. By these steps we avoided introducing errors of several thousand Kelvin to our temperature measurements in the halo. For IC3568 we detected a halo. For M2-2 we found a halo radius that is 2.5 times larger... (abridged)
