  Convection, pulsation and magnetic fields have all been suggested as
mechanisms for the transport of mass and energy from the optical photosphere of
red supergiants, out to the region where the stellar wind is launched. We
imaged the red supergiant Betelgeuse at 0.06-0.18 arcsec resolution, using
e-MERLIN at 5.5--6.0 GHz, with a sensitivity of ~0.01 mJy/beam. Most of the
radio emission comes from within an ellipse (0.235x0.218) arcsec^2 (~5x the
optical radius), with a flux density of 1.62 mJy, giving an average brightness
temperature ~1250 K. This radio photosphere contains two hotspots of 0.53 and
0.79 mJy/beam, separated by 90 milli-arcsec, with brightness temperatures
5400+/-600 K and 3800+/-500 K. Similar hotspots, at more than double the
distance from the photosphere of those seen in any other regime, were detected
by the less-sensitive `old' MERLIN in 1992, 1995 and 1996 and many exceed the
photospheric temperature of 3600 K. Such brightness temperatures are high
enough to emanate from pockets of chromospheric plasma. Other possibilities
include local shock heating, the convective dredge-up of hot material or
exceptionally cool, low density regions, transparent down to the hottest layer
at ~40 milliarcsec radius. We also detect an arc 0.2--0.3 arcsec to the SW,
brightness temperature ~150 K, in a similar direction to extensions seen on
both smaller and larger scales in the infra-red and in CO at mm wavelengths.
These preliminary results will be followed by further e-MERLIN, VLA and ALMA
observations to help resolve the problem of mass elevation from 1 to 10 R* in
red supergiants.
