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12th of April 2018
The Puppis A supernova remnant
Reynoso et al. present a polarization study towards the relatively young supernova remnant Puppis A, based on observations performed with the Australia Telescope Compact Array. Based on the analysis of a feature detected outside the SNR shell, they were able to disentangle the emission originating in Puppis A itself from that coming from the foreground Vela SNR. They found a very low polarization fraction, of about 3 percent on average, and placed an upper limit on the magnetic field component parallel to the line of sight of about 20 microgauss. There is evidence that the magnetic vectors along the shell are aligned with the shock front direction. The low polarization fraction and the statistical behavior of the magnetic vectors are compatible with a scenario where the supernova remnant evolves inside a stellar wind bubble launched by the supernova progenitor star. This scenario can furthermore explain the morphology of Puppis A, rendering little support to the previously accepted picture which involved strong density gradients to explain the flat, eastern edge of the shell.

The image above shows the polarized intensity of Puppis A at 2.24 GHz. The color scale, in mJy per beam, is shown in the bar at the right. Total intensity contours at 50, 100, 250, 600, and 1000 mJy per beam are overlaid in white. The yellow circle at the top right corner represents the 2 arcminute beam. Results are presented in the preprint of the paper.

Note: this ADAP was originally scheduled for April 4th, but due to a technical glitch did not display on that day

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