What type of star is V838 Mon (Monocerotis) considered to be?

V838 Monocerotis is classified as a red variable star due to its notable outburst and variation in brightness following its eruption in 2002. Initially, the star experienced a significant increase in luminosity, becoming one of the brightest stars in the Milky Way for a brief period. This behavior is characteristic of red variable stars, which are known for their fluctuations in brightness over time, often as a result of expanding and contracting outer layers.

The classification of V838 Mon as a red variable star aligns with its observed color, temperature, and behavior. After its outburst, it exhibited a shift to a cooler, redder spectrum, reinforcing its classification in this category. Thus, the definition and characteristics of red variable stars are key to understanding why V838 Mon fits into this classification.