ALMA and VLA reveal the lukewarm chromospheres of the nearby red supergiants Antares and Betelgeuse

@article{OGorman2020ALMAAV,
  title={ALMA and VLA reveal the lukewarm chromospheres of the nearby red supergiants Antares and Betelgeuse},
  author={Eamon O’Gorman and Graham M. Harper and Keiichi Ohnaka and Anton Feeney-Johansson and K. Wilkeneit-Braun and Anthony Brown and Edward F. Guinan and Jeremy Lim and Anita M. S. Richards and Nils Ryde and Wouter H. T. Vlemmings},
  journal={Astronomy \& Astrophysics},
  year={2020}
}
We first present spatially resolved ALMA and VLA continuum observations of the early-M red supergiant Antares to search for the presence of a chromosphere at radio wavelengths. We resolve the free-free emission of the Antares atmosphere at 11 unique wavelengths between 0.7 mm (ALMA band 8) and 10 cm (VLA S band). The projected angular diameter is found to continually increase with increasing wavelength, from a low of 50.7 mas at 0.7 mm up to a diameter of 431 mas at 10 cm, which corresponds to… 

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