Great Dimming of RW Cep
Mass loss plays a central role in the final evolutionary stages of massive stars, and with the Great Dimming of Betelgeuse in 2019 – 2020 there is a renewed interest in episodic mass loss events that occur in luminous supergiants. The cool hypergiant star RW Cep experienced a similar but longer duration Great Dimming event in 2022, and the star was imaged with the CHARA Array near photometric minimum and during the re-brightening phase by Anugu et al. (2023, 2024). The reconstructed H- and K-band images show an asymmetric intensity distribution and a distorted shape perhaps related to the limited knowledge about the faint limb-darkened edge. Contemporaneous near-IR spectroscopy demonstrated that the amount of fading increased towards shorter wavelengths, and this implicates dust formation from stellar ejecta as the explanation for the fading and unusual appearance. Anugu and colleagues are continuing to monitor the star with CHARA to explore how the surface appearance changes as the star brightens again.
References:
Time-Evolution Images of the Hypergiant RW Cephei During the Re-brightening Phase Following the Great Dimming
Anugu, N. et al., 2024, Astrophysical Journal Letters 973, 5
The Great Dimming of the hypergiant star RW Cephei: CHARA Array images and spectral analysis
Anugu, N. et al., 2023, Astronomical Journal, 166, 78