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Zooming in on Supernova 1987A at sub-mm wavelengths

Supernova 1987A (SN1987A) in the neighbouring Large Magellanic Cloud offers a superb opportunity to follow the evolution of a supernova and its remnant in unprecedented detail. Recently, far-infrared (far-IR) and sub-mm emission was detected from the direction of SN1987A, which was interpreted as due to the emission from dust, possibly freshly synthesized in the SN ejecta. To better constrain the location and hence origin of the far-IR and sub-mm emission in SN1987A, we have attempted to resolve the object in that part of the electro-magnetic spectrum. We observed SN1987A during July-September 2011 with the Atacama Pathfinder EXperiment (APEX), at a wavelength of 350 micron with the Submillimetre APEX Bolometer CAmera (SABOCA) and at 870 micron with the Large APEX BOlometer CAmera (LABOCA). The 350-micron image has superior angular resolution (8") over that of the Herschel Space Observatory 350-micron image (25"). The 870-micron observation (at 20" resolution) is a repetition of a similar observation made in 2007. In both images, at 350 and 870 micron, emission is detected from SN1987A, and the source is unresolved. The flux densities in the new (2011) measurements are consistent with those measured before with Herschel at 350 micron (in 2010) and with APEX at 870 micron (in 2007). A higher dust temperature (approximately 33 K) and lower dust mass might be possible than what was previously thought. The new measurements, at the highest angular resolution achieved so far at far-IR and sub-mm wavelengths, strengthen the constraints on the location of the emission, which is thought to be close to the site of SN1987A and its circumstellar ring structures. These measurements set the stage for upcoming observations at even higher angular resolution with the Atacama Large Millimeter Array (ALMA).