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Title: The Great Dimming of the Hypergiant Star RW Cephei: CHARA Array Images and Spectral Analysis
Abstract

The cool hypergiant star RW Cephei is currently in a deep photometric minimum that began several years ago. This event bears a strong similarity to the Great Dimming of the red supergiant Betelgeuse that occurred in 2019–2020. We present the first resolved images of RW Cephei that we obtained with the CHARA Array interferometer. The angular diameter and Gaia distance estimates indicate a stellar radius of 900–1760R, which makes RW Cephei one of the largest stars known in the Milky Way. The reconstructed, near-infrared images show a striking asymmetry in the disk illumination with a bright patch offset from the center and a darker zone to the west. The imaging results depend on assumptions made about the extended flux, and we present two cases with and without allowing extended emission. We also present a recent near-infrared spectrum of RW Cep that demonstrates that the fading is much larger at visual wavelengths compared to that at near-infrared wavelengths as expected for extinction by dust. We suggest that the star’s dimming is the result of a recent surface mass ejection event that created a dust cloud that now partially blocks the stellar photosphere.

 
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Award ID(s):
1909165 1908026 2034336 1814777
PAR ID:
10436953
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astronomical Journal
Volume:
166
Issue:
2
ISSN:
0004-6256
Format(s):
Medium: X Size: Article No. 78
Size(s):
Article No. 78
Sponsoring Org:
National Science Foundation
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