# Atmosphere of Betelgeuse before and during the Great Dimming event revealed by tomography

**Authors:** K. Kravchenko, A. Jorissen, S. Van Eck, T. Merle, A. Chiavassa, C. Paladini, B. Freytag, B. Plez, M. Montargès, H. Van Winckel  
**arXiv:** [2104.08105](https://arxiv.org/abs/2104.08105)  
**Date:** 2021-04-16  
**Summary page:** https://www.summarizepaper.com/en/paper/2104.08105v1/

## Key points

- Betelgeuse is the best studied red supergiant star in our Galaxy
- The physics behind its photometric variability and mass loss is poorly understood
- Betelgeuse recently experienced an unusual fading event with historical minimum visual magnitude
- A team of researchers used a tomographic technique to analyze high-resolution spectroscopic observations of Betelgeuse taken over a few years
- The tomographic method allowed them to probe different depths in the stellar atmosphere and recover the corresponding disk-averaged velocity field
- There was a sudden increase in molecular opacity in the cooler upper atmosphere of Betelgeuse during the fading event, which likely caused the observed decrease in brightness
- This research provides insights into understanding photometric variability and mass loss of red supergiant stars like Betelgeuse
- Tomography allows for detailed analysis of atmospheric dynamics and can uncover important factors contributing to stellar evolution and variability
- The study contributes to our knowledge of Betelgeuse and complex processes within red supergiant stars
- Further research will enhance our understanding of these massive celestial objects and their role in shaping our universe.

## Summary

Despite being the best studied red supergiant star in our Galaxy, the physics behind the photometric variability and mass loss of Betelgeuse is still poorly understood. Recently, Betelgeuse experienced an unusual fading event with its visual magnitude reaching a historical minimum. To investigate this event further, a team of researchers led by K. Kravchenko applied a recently developed tomographic technique to high-resolution spectroscopic observations taken over a few years. This tomographic method allowed them to probe different depths in the stellar atmosphere and recover the corresponding disk-averaged velocity field. By analyzing these observations, they aimed to relate the atmospheric dynamics of Betelgeuse to its photometric variability. The results revealed that there was a sudden increase in molecular opacity in the cooler upper atmosphere of Betelgeuse which is likely responsible for the observed decrease in brightness during the fading event. This research provides valuable insights into understanding the mechanisms behind photometric variability and mass loss of red supergiant stars like Betelgeuse. The application of tomography allows for a detailed analysis of atmospheric dynamics and can help uncover important factors contributing to stellar evolution and variability. Overall, this study contributes to our knowledge of Betelgeuse and sheds light on complex processes occurring within red supergiant stars. Further research in this area will continue to enhance our understanding of these massive celestial objects and their role in shaping our universe.