CHARA Near-infrared Imaging of the Yellow Hypergiant Star ρ Cassiopeiae: Convection Cells and Circumstellar Envelope
Year: 2024
Type: article
Abstract: Massive evolved stars such as red supergiants and hypergiants are potential progenitors of Type II supernovae, and they are known for ejecting substantial amounts of matter, up to half their initial mass, during their final evolutionary phases. The rate and mechanism of this mass loss play a crucial role in determining their ultimate fate and the likelihood of their progression to supernovae. However, the exact mechanisms driving this mass ejection have long been a subject of research. Recent observations, such as the Great Dimming of Betelgeuse, have suggested that the activity of large convective cells, combined with pulsation, could be a plausible explanation for such mass-loss events. In this context, we conducted interferometric observations of the famous yellow hypergiant, ρ Cassiopeiae using the CHARA Array in H- and K-band wavelengths. ρ Cas is well known for its recurrent eruptions, characterized by periods of visual dimming (∼1.5–2 mag) followed by recovery. From our observations, we derived the diameter of the limb-darkened disk and found that this star has a radius of 1.04 ± 0.01 mas, or 564–700 R ⊙. We performed image reconstructions with three different image reconstruction software packages, and they unveiled the presence of giant hot and cold spots on the stellar surface. We interpret these prominent hot spots as giant convection cells, suggesting a possible connection to mass ejections from the star’s envelope. Furthermore, we detected spectral CO emission lines in the K band (λ = 2.31–2.38 μm), and the image reconstructions in these spectral lines revealed an extended circumstellar envelope with a radius of 1.45 ± 0.10 mas.
Source: The Astrophysical Journal
Authors: Narsireddy Anugu, Fabien Baron, John D. Monnier, Douglas R. Gies, Rachael M. Roettenbacher, Gail H. Schaefer, Miguel Montargès, Stefan Kraus, Jean-Baptiste Le Bouquin, Matthew D. Anderson, Theo ten Brummelaar, Isabelle Codron, Christopher D. Farrington, Tyler Gardner, Mayra Gutierrez, Rainer Köhler, Cyprien Lanthermann, Ryan Norris, Nicholas J. Scott, Benjamin R. Setterholm, Norman L. Vargas
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, National Aeronautics and Space Administration, Georgia State University, European Commission, Division of Astronomical Sciences, Office of the Vice President for Research and Economic Development, University at Buffalo, H2020 European Research Council, HORIZON EUROPE European Research Council
Awards: Collaborative Research: Imaging planet-forming disks around young Suns using a revolutionary infrared detector, THE EXOPLANET FIELD HAS REMAINED VIBRANT AND EXCITING DUE TO THE CONTINUOUS DEVELOPMENT OF NEW OBSERVING TECHNIQUES AND THE REFINEMENT OF OLDER ONES,, Collaborative Research: First Science with the Michigan Young STar Imager at CHARA (MYSTIC), G3816470682, G434337789, G5434558782, G6132391133, Imaging Convective Patterns On AGB Stars, High Angular Resolution Investigations of Binary Stars and their Disks, Enabling Milliarcsecond Astrophysics: Open access for the CHARA Array, G7182325560, Exploring the Milliarcsecond Frontier: Open access to the renewed CHARA Array, G8466163884, G8529376552, Paris Region Fellowship Programme, Imaging the Dynamical Imprints of Planet Formation in Protoplanetary Discs, G955576425, A Leap in Sensitivity for CHARA/CLASSIC Optical Interferometry for Astronomy
OpenAlex ID: W4403230922