  Massive evolved stars such as red supergiants and hypergiants are potential
progenitors of Type II supernovae, and they are known for ejecting substantial
amounts of matter, up to half their initial mass, during their final
evolutionary phases. The rate and mechanism of this mass loss play a crucial
role in determining their ultimate fate and the likelihood of their progression
to supernovae. However, the exact mechanisms driving this mass ejection have
long been a subject of research. Recent observations, such as the Great Dimming
of Betelgeuse, have suggested that the activity of large convective cells,
combined with pulsation, could be a plausible explanation for such mass loss
events. In this context, we conducted interferometric observations of the
famous yellow hypergiant, $\rho$ Cassiopeiae using the CHARA Array in H and
K-band wavelengths. $\rho$ Cas is well known for its recurrent eruptions,
characterized by periods of visual dimming ($\sim$1.5-2 mag) followed by
recovery. From our observations, we derived the diameter of the limb-darkened
disk and found that this star has a radius of $1.04\pm0.01$ milliarcseconds
(mas), or $564 - 700 R_\odot$. We performed image reconstructions with three
different image reconstruction software packages, and they unveiled the
presence of giant hot and cold spots on the stellar surface. We interpret these
prominent hot spots as giant convection cells, suggesting a possible connection
to mass ejections from the star's envelope. Furthermore, we detected spectral
CO emission lines in the K-band ($\lambda=2.31-2.38 \mu$m), and the image
reconstructions in these spectral lines revealed an extended circumstellar
envelope with a radius of $1.45\pm0.10$ mas.
