Proposal #529

I would like to monitor the hypergiant star RW Cep long-term, to track further photometric and spectroscopic evolution after the recovery of the recent "great dimming". It should be observed in all available filters (BVRI) to track not only the magnitude but also the color evolution. It should be observed approximately once a week. Spectroscopic observations do not need to be as frequent, around once a month seems sufficient. They should ideally be as high resolution as possible. The goal with spectroscopy is to track the evolution of various spectral features, and to monitor any spectral changes if they occur. Various papers have assigned different spectral types to the star, differing only due to the classification method used, so spectroscopic observations would allow us to get a sense of the true range of spectroscopic varability.

It is difficult to say for sure how long the campaign should last for, as it is impossible to predict when the star might start doing something interesting again. The star is currently being monitored by the CHARA array, so having photometric and spectroscopic data at least covering these observations would be very useful to the CHARA team. It is however also currently undecided how long the star will be observed by CHARA. The project is being led by Narsireddy Anugu. I hope to at the very least monitor the star for the next few years.

It should also be noted that the magnitude can in some cases approach V=6, and there is a small chance it may briefly reach a magnitude V<6. The magnitude is currently at around 6.5.