WOH G64: A Review on Red Supergiant in Transition

WOH G64, a symbiotic binary in the Large Magellanic Cloud, is one of the most extreme red supergiants known, with a radius approximately 1,540 times that of the Sun and a luminosity around 282,000 times the solar luminosity. Recent observations suggest that WOH G64 is undergoing significant changes, including a transition from semi regular to irregular variability and a decrease in brightness. The star's spectrum has changed, showing emission lines from ionized gas and a newly formed dust cloud has been detected. However, spectroscopic observations indicate that WOH G64 remains a red supergiant, with molecular absorption bands from titanium oxide (TiO) still present. A proposed explanation for these changes is the presence of a binary companion, which is interacting with WOH G64 and causing its atmosphere to expand. This interaction may lead to the formation of a yellow hypergiant or even a supernova explosion.