Luken et al. present 1 to 10 GHz radio continuum flux density,
spectral index, polarisation and Rotation Measure images of the
youngest known Galactic supernova remnant (SNR) G1.9+0.3, using observations from the
ATCA. Combining their data with archival data sets dating back to
1984, they conducted an expansion study and find a mean radio
continuum expansion rate of (0.78 ± 0.09) per cent per year (or 8900
km/s at an assumed distance of 8.5 kilo-parsecs), consistent with
The expansion rate varies around the SNR perimeter, with a faster
expansion observed in the northern region, as indicated by the figure
above and suggestive of expansion into an inhomogeneous medium.
The expansion into the stellar wind of a Red Super Giant star
progenitor could potentially explain the polarisation characteristics
we observe for SNR G1.9+0.3. This hypothesis, however, would have
difficulties explaining hydrodynamic properties of the remnant and its
observed X-ray emission.
More details are given in
to be published in Monthly Notices of the Royal Astronomical Society.