New Observations Reveal WOH G64 Remains a Red Supergiant
Recent studies indicate that WOH G64, a massive star in the Large Magellanic Cloud, continues to exhibit characteristics of a red supergiant, challenging previous beliefs about its imminent transition to a yellow hypergiant.
Recent observations have provided new insights into WOH G64, a massive star located approximately 160,000 light-years away in the Large Magellanic Cloud.
Previously, WOH G64 was thought to be transitioning from a red supergiant to a yellow hypergiant, a stage often preceding a supernova explosion. This belief was based on the star's significant dimming and the detection of an egg-shaped cocoon of gas and dust surrounding it.
However, a study led by Dr. Jacco van Loon from Keele University, in collaboration with Dr. Keiichi Ohnaka from Universidad Andrés Bello in Chile, challenges this assumption. The team conducted detailed observations using the Southern African Large Telescope (SALT) between November 2024 and December 2025. Their findings revealed the presence of titanium oxide (TiO) in the star's atmosphere, a molecule indicative of cooler temperatures associated with red supergiants.
Dr. van Loon stated, "WOH G64 has been claimed to have turned into a yellow hypergiant, which could signal a pre-supernova post-red supergiant evolution. However, our new spectra obtained with SALT show the hot companion's presence but also clear molecular absorption bands from Titanium Oxide (TiO). This implies that WOH G64 is currently a red supergiant and may never have ceased to be."
The study also suggests that WOH G64 may be part of a binary system, with a smaller, likely blue, companion star interacting with it. This interaction could explain the star's unusual behavior, including the formation of the surrounding dust cocoon.
These findings provide valuable insights into the complex life cycles of massive stars and highlight the importance of continuous observation to understand their evolution.