Max Planck Institute for Astronomy | 2020 Jun 29
Gigantic star spots are probably the reason for the recent drop in brightness of the red giant star
Betelgeuse, the bright star in the constellation of Orion, has been fascinating astronomers in the recent months because of its unusually strong decline in brightness. Scientists have been discussing a number of scenarios trying to explain its behaviour. Now a team ... have shown that most likely unusually large star spots on the surface of Betelgeuse have caused the dimming. Their results rule out the previous conjecture that it was dust, recently ejected by Betelgeuse, which obscured the star. ...
Red giant stars like Betelgeuse undergo frequent brightness variations. However, the striking drop in Betelgeuse's luminosity to about 40% of its normal value between October 2019 and April 2020 came as a surprise to astronomers. Scientists have developed various scenarios to explain this change in the brightness of the star, which is visible to the naked eye and almost 500 light years away. Some astronomers even speculated about an imminent supernova. An international team of astronomers ... have now demonstrated that temperature variations in the photosphere, i.e. the luminous surface of the star, caused the brightness to drop. The most plausible source for such temperature changes are gigantic cool star spots, similar to sunspots, which, however, cover 50 to 70% of the star’s surface. ...
Betelgeuse Fainter in the Submillimeter Too: An Analysis of JCMT and APEX
Monitoring During the Recent Optical Minimum ~ Thavisha E. Dharmawardena et al
- Astrophysical Journal Letters 897(1):L9 (2020 Jul 01) DOI: 10.3847/2041-8213/ab9ca6
- arXiv.org > astro-ph > arXiv:2006.09409 > 16 Jun 2020