The quest for hidden populations of evolved massive stars with MeerKAT
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The evolution of disk galaxies is strongly influenced by their populations of massive stars, which through their copious and energetic stellar winds provide both processed material and energy to the ISM, triggering the formation of new generations of stars.
The intense UV fields and conspicuous mass-loss of massive stars heavily alter the morphology of the local ISM, leaving an unmistakable footprint onto their surroundings: from large cavities, carved out in nearby molecular clouds, to dense, expanding circumstellar nebulae of dust and gas.
Despite the undeniable relevance of massive stars, the details of their post-MS evolution are far from being completely understood. Theoretical models predict a succession of rapidly evolving, unstable transitional stages towards their inevitable end as core-collapse supernovae. Still, many questions regarding these intermediate evolutionary phases remain open, and the only observational support for these models comes down to a handful of objects in each stage. Therefore, finding and characterizing new evolved massive star candidates emerges as a very critical yet complex task.
Radio observations are a very convenient ways to investigate the footprint of evolved stars, thanks to the ability of radio waves to penetrate the obscuring matter in the line of sight, that may hamper the detection at shorter wavelengths.
In this talk, results from our quest for massive evolved stars will be presented. MeerKAT, thanks to its superb sensitivity, angular resolution and uv coverage, has already proven to be the ideal instrument to unveiling hidden populations of evolved massive stars.
MeerKAT has revealed a radio continuum sky rich in structures associated with massive stars. Dozens of extended continuum structures linked to WRs and LBVs have been found in the SARAO MeerKAT L-band Galactic Plane Survey and many other new rings and shells, with no matching entries in catalogues of known evolved objects, have been identified.