RW Cephei, Among the Biggest Stars in the Milky Way, Faces its Final Act in a Colossal Eruption

In the vast Milky Way, RW Cephei stands out as one of the largest stars, currently undergoing a transformative phase that has left astronomers intrigued. Recently, a deep photometric minimum began, similar to Betelgeuse’s Great Dimming in 2019–2020. This event has brought forth the first resolved images obtained with the CHARA Array interferometer.

A Star of Extraordinary Dimensions: The CHARA Array’s estimates reveal a stellar radius for RW Cephei ranging from 900 to 1760 R⊙, solidifying its status as one of the largest stars in the Milky Way. These findings contribute to the ongoing exploration of this cool hypergiant star’s colossal dimensions.

Asymmetry in Illumination: The near-infrared images of RW Cephei reveal a striking asymmetry in the disk illumination, with a bright patch offset from the center and a darker zone to the west. Reconstruction of these images, dependent on assumptions about extended flux, offers insights into the star’s complex dynamics.

Dimming Explained: RW Cephei’s observed dimming is now believed to result from a recent surface mass ejection event, creating a colossal dust cloud partially obstructing the stellar photosphere. A recent near-infrared spectrum of RW Cep further supports this theory, showcasing a larger fading at visual wavelengths compared to near-infrared wavelengths, consistent with extinction by dust.

A Cosmic Cataclysm Unfolds: The recent deep photometric minimum, coupled with resolved images and spectral analysis, paints a vivid picture of RW Cephei’s current state. Astronomers propose that the star’s evolving behavior signifies the concluding chapters of its cosmic journey, akin to multiple dimming events in the past century.

Conclusion: As RW Cephei continues to captivate astronomers with its colossal eruption and mysterious dimming, the CHARA Array plays a pivotal role in unraveling the mysteries surrounding this cosmic giant. The unfolding drama in the depths of the Milky Way serves as a testament to ongoing exploration and the marvels hidden within the cosmos.

You can read the published paper here.